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The cerebellum and dyslexia
Abstract
BLDSC reference no.: D222900. Thesis (D. Phil.)--University of Oxford, 2002. Includes bibliographical references.
... The most prominent theory about origin of dyslexia proposes that cognitive deficiencies in phonological processing, which can be defined as ability to decode and manipulate phonemes or difficulty associating letters with the appropriate sounds (4)(5)(6)(7). In addition to phonological and literacy difficulties in dyslexia, many studies have focused on the effects of the cerebellum and its functions (8)(9)(10). The cerebellum could contribute to reading in various aspects, including eye movements, language and spatial processing, working memory, and skill acquisition and automaticity (8). ...
... In addition to phonological and literacy difficulties in dyslexia, many studies have focused on the effects of the cerebellum and its functions (8)(9)(10). The cerebellum could contribute to reading in various aspects, including eye movements, language and spatial processing, working memory, and skill acquisition and automaticity (8). Thus, while cerebellar dysfunction is not likely the primary cause of dyslexia, impairments on cerebellar tasksincluding eye movement control, postural stability, and implicit motor learning could be shown in children and adults with dyslexia (9). ...
... The mean age of the SG was 9.80 ± 1.99 years (range [6][7][8][9][10][11][12][13][14], and there were six female and nine male participants; the mean age of the CG was 9.13 ± 2.42 years (range 6-12) and there were seven female and eight male participants. Table 1 shows descriptive statistics results. ...
Purpose
The aim of this study is to compare functionality of vestibulo-ocular reflex (VOR) responses to evaluate the functional properties of the vestibular system and daily balance performance in children with dyslexia and children with normal development.
Method
Fifteen participants diagnosed with dyslexia were included in the study group (SG), and 15 healthy participants were included in the control group (CG). All groups underwent Functional Head Impulse Test (f-HIT) and Pediatric Balance Scale (PBS). f-HIT was performed with at least 15 head impulses at 4000-5000-6000°/s ² randomly to the right and left in the plane of the horizontal semicircular canal (SCC). Statistical analysis was performed using descriptive statistics and the Mann-Whitney U test.
Results
SG percentage values were obtained lower than CG percentage values. Comparisons between the two groups showed that there was a significant difference in all parameters (4000-5000-6000°/s ² and total) in the right-side stimulation, there was significant difference for 4,000 s ² and total correct answers in the left side. In addition, although there was no significant difference between the groups in terms of the PBS score, the SG scores were lower ( p = 0.062).
Conclusions
As a novel test, f-HIT, revealed the difference in functionality of vestibular performance in the dyslexia group. In the dyslexia group, f-HIT may be helpful in evaluating and monitoring the vestibular system.
... Currently, there is a consensus that dyslexia is a neurobehavioural disorder (Fawcett & Nicolson, 1999;Katzir, 2009;Paulesu et al., 2001) that affects reading and several other behaviours, thereby leading to a much broader spectrum of behavioural changes. Despite many attempts, the aetiology of dyslexia is not established to date (Stoodley & Stein, 2011;Stoodley & Stein, 2013), and even the suggestion of mild deficit in the cerebellar structures motivates intense debate (Stoodley & Stein, 2011). Furthermore, several studies view these types of suggestions with considerable scepticism (Irannejad & Savage, 2012;Stoodley & Stein, 2011;Stoodley & Stein, 2013). ...
... Currently, there is a consensus that dyslexia is a neurobehavioural disorder (Fawcett & Nicolson, 1999;Katzir, 2009;Paulesu et al., 2001) that affects reading and several other behaviours, thereby leading to a much broader spectrum of behavioural changes. Despite many attempts, the aetiology of dyslexia is not established to date (Stoodley & Stein, 2011;Stoodley & Stein, 2013), and even the suggestion of mild deficit in the cerebellar structures motivates intense debate (Stoodley & Stein, 2011). Furthermore, several studies view these types of suggestions with considerable scepticism (Irannejad & Savage, 2012;Stoodley & Stein, 2011;Stoodley & Stein, 2013). ...
... Despite many attempts, the aetiology of dyslexia is not established to date (Stoodley & Stein, 2011;Stoodley & Stein, 2013), and even the suggestion of mild deficit in the cerebellar structures motivates intense debate (Stoodley & Stein, 2011). Furthermore, several studies view these types of suggestions with considerable scepticism (Irannejad & Savage, 2012;Stoodley & Stein, 2011;Stoodley & Stein, 2013). Despite difficulties in establishing a causal relationship, our results clearly indicate that children with dyslexia are less efficient when compared to their peers in the processing of multisensory information as opposed to only visual information. ...
The study involved investigating dyslexic children's postural control responses when visual and somatosensory cues were separately manipulated. Twenty dyslexic and 19 nondyslexic children performed a trial by standing upright inside a moving room and another by lightly touching a moving bar. Both trials lasted 240 s with the following three different stimulus characteristics: low (pretransition), high (transition), and low amplitude (posttransition). Body sway magnitude and the relationship between the movement of the room/bar surface and body sway were examined. When compared to nondyslexic children, dyslexic children oscillated with higher magnitude in the transition and posttransition under visual and somatosensory manipulation; their sway was more influenced by visual manipulation in the transition and posttransition, and they used higher applied force levels in the somatosensory modality in all conditions. The results suggest that dyslexic children could not efficiently reweight visual cues when compared to nondyslexic children. The same was not observed in the somatosensory cues when dyslexic children reduced the influence of the somatosensory stimulus. The proper use of somatosensory information was related to stronger acquired cues and higher applied forces as observed for dyslexic children. Dyslexic children experience difficulties in dynamically reweighting sensory cues although these types of difficulties are overcome when more informative sensory cues are provided.
... Taking into account previous evidence showing a reduction of gray matter in specific cerebellar regions associated with DD or other types of dyslexia, such as inferior frontal gyrus, precentral gyrus, medial occipital gyri, frontal and occipital lobes, insula and basal ganglia (Brambati et al., 2004;Zadina et al., 2006), a VBM analysis was performed to investigate potential global volumetric changes in relevant brain regions. This analysis revealed anomalous leftward anatomical asymmetries, consistent with other studies in dyslexic brains (Stoodley and Stein, 2011). ...
... right; GA: 0.32 vs. normal range 0.10-0.21, and left; GA: 0.30 vs. normal range 0.10-0.21; Figure 1B The VBM findings reveal anomalous anatomical asymmetries, which support the argument that the cerebellum is one of the main regions associated with dyslexia with consistent differences between critical groups (Eckert, 2004;Stoodley and Stein, 2011;Vandermosten et al., 2016). More importantly, the results from the lobular analysis and the DAST are consistent with the findings of Stanberry et al. (2006), namely, that the asymmetries of lobules V, Crus II, VIIB, and X are involved in difficulties of postural stability, rapid naming, rapid reading, phonemic segmentation, and memory. ...
... Interestingly, although GA was diagnosed with dyslexia quite early, he achieved advanced degrees, indicating that the recorded brain asymmetries do not merely represent differences in reading experience, but rather they may actually contribute with a causative role in dyslexia (Vandermosten et al., 2016). Worthy of mention is that the emotional and/or behavioral characteristics of GA's profile are not classified in the clinical spectrum, indicating that: (i) the cerebellum asymmetries may be specific to his learning difficulties (Stoodley and Stein, 2011); and (ii) the amygdala asymmetries might reflect alterations in the expression of neuroplasticity genes, which could be triggered by the frustration that the persistent learning difficulties evoke as it has been previously suggested (Blair, 2010), affecting his behavior and stimulus reinforcement learning. However, it would have been certainly interesting to have access to information concerning earlier life periods of the subject examined, as to the form and degree of his dyslexia, because the data presented here only refer to adult findings (Shaywitz et al., 2002). ...
Developmental dyslexia (DD) is a multi-system disorder, combining influences of susceptibility genes and environmental factors. The causative interaction between specific genetic factors, brain regions, and personality/mental disorders, as well as specific learning disabilities, has been thoroughly investigated with regard to the approach of developing a multifaceted diagnostic procedure with an intervention strategy potential. In an attempt to add new translational evidence to the interconnection of the above factors in the occurrence of DD, we performed a combinatorial analysis of brain asymmetries, personality traits, cognitive and learning skills, and expression profiles of selected genes in an adult, early diagnosed with DD, and in his son of typical development. We focused on the expression of genes, based on the assumption that the regulation of transcription may be affected by genetic and epigenetic factors. The results highlighted a potential chain link between neuroplasticity-related as well as stress-related genes, such as BDNF, Sox4, mineralocorticoid receptor (MR), and GILZ, leftward asymmetries in the amygdala and selective cerebellum lobules, and tendencies for personality disorders and dyslexia. This correlation may reflect the presence of a specific neuro-epigenetic component of DD, ensuing from the continuous, multifaceted difficulties in the acquisition of cognitive and learning skills, which in turn may act as a fostering mechanism for the onset of long-term disorders. This is in line with recent findings demonstrating a dysfunction in processes supported by rapid neural adaptation in children and adults with dyslexia. Accordingly, the co-evaluation of all the above parameters may indicate a stress-related dyslexia endophenotype that should be carefully considered for a more integrated diagnosis and effective intervention.
... Et selon , la dyslexie est caractérisée par des difficultés dans la reconnaissance exacte et/ou fluide de mots ainsi que par une orthographe des mots (spelling), et des capacités de décodage limitées. Plus spécifiquement, la dyslexie est un trouble spécifique des apprentissages de la lecture qui se manifeste comme une difficulté à apprendre à lire chez un enfant malgré un enseignement adapté, une intelligence adéquate et un bon environnement socio-éducatif (Habib,2002, Stoodley & Stein, 2011. La dysorthographie quant à elle, est caractérisée par des troubles de la transcription phonologique, des troubles du contrôle sémantique, des troubles morphosyntaxiques, et des troubles du lexique orthographique. ...
... En effet, contrairement à certaines recherches sur la dyslexie et la dysorthographie, qui se passent dans des zones où la langue maternelle de l'enfant est en même temps sa langue principale d'enseignement, nous avons mené notre étude dans une zone où cela diffère. Les recherches de Habib (2002) et Stoodley et Stein (2011) se sont menées par exemple dans une zone anglophone, avec comme langue d'enseignement l'anglais. Par contre, chez nous la langue maternelle de nos sujets est soit le mooré, soit le gourounsi, soit le dioula ou autres langues. ...
La dyslexie et la dysorthographie sont des troubles spécifiques de l’apprentissage/acquisition de la lecture et de l’écriture. Cette recherche porte sur « la dyslexie et la dysorthographie : répercussion sur l’apprentissage/acquisition des langues secondes chez les élèves du secondaire au Burkina Faso ». Les résultats de ce travail permettent de comprendre l’influence de cette dyslexie et de cette dysorthographie sur l’apprentissage/acquisition des langues secondes chez ces élèves. L’étude identifie les difficultés d’apprentissage/acquisition des langues chez ces apprenants, analyse la relation entre ces potentielles difficultés. Par une démarche qualitative et quantitative, nous avons utilisé des outils de diagnostics, choisi un échantillon de trente-deux (32) personnes sur lesquelles nous avons fait passer des épreuves de lecture et d’écriture. Cela a constitué notre base de données. Les résultats révèlent que la dysorthographie est plus fréquente que la dyslexie chez les apprenants enquêtés. Aussi, beaucoup de difficultés sont observées dans l’apprentissage/acquisition des langues secondes en rapport avec les troubles dyslexiques et dysorthographiques.
... In addition to the studies that directly measured children with dyslexia's performance in handwriting, research has investigated the motor abilities in dyslexic samples, which are fundamental for graphomotor processes required for handwriting (Van Galen, 1991). Such studies have demonstrated that dyslexic samples performed lower than typically developing participants on various motor-related tasks, also called cerebellar tasks (for a review see Stoodley & Stein, 2011). Such observations led Nicolson and colleagues to propose the cerebellar deficit theory of dyslexia (Nicolson et al., 2001), which has been the focus of several experiments since then and at the centre of controversy. ...
... Moreover, as suggested by van Oers et al. (2018), future experiments involving more participants should characterise different subgroups of dyslexia. Indeed, it is plausible that only a portion of participants with dyslexia presented additional nonliteracy difficulties, such as those observed for handwriting (Alamargot et al., 2020;Martlew, 1992) or various cerebellar tasks (for a review see Stoodley & Stein, 2011). This characteristic leads us to another shortcoming of this experiment concerning the limited behavioural assessment of participants. ...
Aim
Children with dyslexia (DYS) have a deficit in spelling (i.e., central processes of writing), and past experiments have suggested that they also frequently experience difficulties in handwriting (i.e., motor peripheral processes of writing) compared with typically developing children (TD). However, the presence of handwriting difficulties in dyslexia is controversial. This experiment aimed to better understand the writing difficulties in DYS children, investigating both the central and peripheral processes of writing and combining cognitive and neuroimaging data.
Method
Participants were 14 DYS and 14 TD (Mage = 9.5) children. They were assessed on behavioural measures (i.e., spelling, handwriting and manual dexterity). Structural and functional magnetic resonance imaging (MRI) data were collected. The fMRI task was a word-dictation task performed using pencil and paper and a head coil mirror providing visual feedback.
Results
Behavioural results revealed a clear spelling deficit and poorer handwriting in DYS than in TD. DYS and TD performed equally in handwriting speed and gross manual dexterity. fMRI data were analysed with an ROI approach using nine central ROIs and 10 peripheral ROIs, which constitute the writing network identified in past literature. fMRI results revealed less brain activation in both central and peripheral ROIs in DYS. The main peripheral differences were located in right lobule VI of the cerebellum. Structural data strengthened the presence of bilateral cerebellar abnormalities in dyslexia.
Conclusion
The present findings constitute a first piece of evidence that children with dyslexia's writing difficulties are not limited to the central processes of writing (i.e., spelling) and that they extend to the peripheral processes of writing (i.e., handwriting). This experiment is the first study to use an fMRI handwriting task to investigate DYS's writing abilities. These results encourage researchers to continue investigating DYS's spelling and handwriting difficulties with a neuroimaging approach. Future experiments are needed to determine whether the functional and structural anomalies observed are consequences of deviant literacy development or whether they could have a causal role in dyslexia.
... Plusieurs hypothèses sur les origines de la dyslexie ont été formulées parmi lesquelles l'hypothèse d'un déficit phonologique (la plus largement admise et sur laquelle nous reviendrons : Snowling & Frith, 2000 ;Vellutino & Fletcher, 2004 ;Shaywitz & Shaywitz, 2005 ;Ramus & Szenkovitz 2008), l'hypothèse de déficits auditifs (Tallal & Piercy, 1973 ;Tallal., al., 1980), l'hypothèse de déficits visuels (Kapoula, Gaertner & Matheron, 2012 ;Quercia, Demougeot, Dos Santos & Bonnetblanc, 2011), et l'hypothèse de troubles cérébelleux ou sensorimoteurs (voir Colé & Sprenger-Charolles 2021 pour une revue, Nicolson et al., 2001, Stoodley & Stein 2011et 2013. Ces hypothèses envisagent les origines de la dyslexie comme mono-factorielles. ...
... et plusieurs études ont évalué la possibilité d'une atteinte sensorimotrice dans la dyslexie, ce qui permet d'envisager une hypothèse alternative selon laquelle le déficit phonologique trouverait son origine dans un déficit plus général(Nicolson & Fawcett 2001, Stoodley & Stein 2011et 2013. De fait, des troubles sensorimoteurs, ont été rapportés chez les individus affectés d'une dyslexie et ce, affectant plus les enfants que les adultes ...
Based on the existence of sensorimotor disorders frequently reported in children and adults with dyslexia (Nicolson & Fawcett, 1999; Ramus et al., 2003 a, Cignetti et al., 2018), this paper focuses on the link between the underlying phonological deficit and a sensorimotor syndrome, or more precisely, between phonemic representation impairment and impairment of internal representations of action. To address this question, we will contribute to the debate with the recent results of two studies in which we tested about fifty dyslexic students, matched with normo-readers, in two protocols of motor ideation and phonemic awareness.
These first results, conducted on a large population, highlight the importance of the comorbidity of the sensorimotor syndrome through an alteration of the internal representations of action and phonemic awareness specific to a subgroup of dyslexic young adults with sensorimotor comorbidity. Thus, sensorimotor impairment does not seem to directly impact on young adults’ reading difficulties, but rather reflects different dyslexic profiles. These results therefore support the existence of a sensorimotor profile that persists in adult dyslexics and also provide further support for the presence of a multiple deficit associated with dyslexia.// FRENCH ABSTRACT : Sur la base de l’existence de troubles sensorimoteurs, fréquemment rapportés dans la littérature chez l’enfant et l’adulte dyslexique (Nicolson & Fawcett, 1999 ; Ramus et al., 2003a, Cignetti et al., 2018), cet article s’intéresse au lien entre déficit phonologique sous-jacent et syndrome sensorimoteur, ou plus précisément entre atteinte phonémique et atteinte des représentations internes de l’action. Pour tenter de répondre à cette question, nous alimenterons le débat par les résultats récents de deux études dans lesquelles nous avons testé une cinquantaine d’étudiants dyslexiques, appariés à des normo-lecteurs, engagés dans deux protocoles d’idéation motrice et de conscience phonémique. Ces premiers résultats effectués sur une large population mettent ainsi en avant l’importance de la comorbidité du syndrome sensorimoteur à travers une altération des représentations internes de l’action et de la conscience phonémique spécifique au sous-groupe de jeunes adultes dyslexiques comorbides. Ainsi, l’atteinte sensorimotrice ne semble pas directement impacter les troubles en lecture des jeunes adultes, mais plutôt refléter des profils dyslexiques différents. Ces résultats soutiennent donc l’existence d’un profil sensorimoteur qui persiste chez les dyslexiques adultes et s’avèrent aussi être un argument de plus en faveur de la présence d’un déficit multiple associé à la dyslexie.
... An estimated 5 to 20% of the population are affected (American Psychiatric Association, 2013;Shaywitz, 1998;Shaywitz et al., 2003;Wagner et al., 2020). Dyslexia's etiology remains the subject of a heated debate with proponents attributing the main underlying cause to deficits in a variety of systems associated with reading (i.e., phonological awareness, visuo-spatial attention, magnocellular and cerebellar function; Stein, 2001Stein, , 2018bStein & Walsh, 1997;Stoodley & Stein, 2011), or to a lack of reading experience (Goswami, 2015;Huettig et al., 2018). While deficits in phonological awareness are considered established (Ramus, 2003(Ramus, , 2014Saksida et al., 2016;Snowling, 1980Snowling, , 1981, other deficits in low-level sensory processing and visual attention remain under scrutiny (e.g., Blythe et al., 2018). ...
... Since even a brief scanning of the area of text just below the current fixation seems rather unintuitive from a cognitive perspective, this finding raises the question whether these directional deviations are the result of occasional issues with oculomotor control previously reported in dyslexia (Biscaldi et al., 1998(Biscaldi et al., , 2000Fischer et al., 1993;Freedman et al., 2017;Stein, 2014Stein, , 2018bStoodley & Stein, 2011Vagge et al., 2015) The aforementioned differences in eye movements are part of the overall visual sampling strategy of text during reading, termed a scanpath. To investigate whether readers with and without dyslexia differ only on some eye movement metrics or rather use a divergent overall visual sampling strategy, we complemented the previous analyses with a computational similarity analysis of the overall scanpath of each trial. ...
Individuals with dyslexia present with reading-related deficits including slow reading speed, and worse text comprehension and word encoding. Reports of visual symptoms such as atypical eye movements during reading gave rise to a search for these deficits’ underlying mechanisms. This study sought to replicate established behavioural deficits in reading and cognitive processing speed while investigating their underlying mechanisms in more detail by developing a comprehensive profile of eye movements specific to reading in adult dyslexia. Using a validated standardized reading assessment, our findings confirm a persistent reading speed deficit among adults with dyslexia. These individuals exhibited slower cognitive processing speed on one type of processing speed task, which correlated with reading speed across all readers. We observed different eye movements in readers with dyslexia across numerous eye movement metrics including the duration of a stop (i.e., fixation), the length of jumps (i.e., saccades), and the number of times a reader’s eyes expressed a jump atypical for reading. We conclude that individuals with dyslexia visually sample written information in a laborious and more effortful manner that is fundamentally different from those without dyslexia. Our findings suggest a mix of aberrant cognitive linguistic and oculomotor processes being present in adults with dyslexia.
... Studies reported that children with dyslexia are having challenges in motor control ability during body balance, movement automaticity, and rhythm and speed (Rochelle & Talcott 2006;Stoodley & Stein 2011;Valdois 2010). Ability to move the body, stabilize and control the movement are parts of gross motor skills (Cools et al. 2007). ...
... Therefore, ball catching was continuously used in many motor assessments to measure motor proficiency in children with disabilities. Other studies indicated that the presence of dyslexia also impaired the balance, motor control, rhythm and speed, and automatization of movement (Okuda et al. 2014;Rochelle & Talcott 2006;Stoodley & Stein 2011). The findings from this study suggest that early intervention for children with dyslexia should emphasize on aiming and catching or ball skills in order to encourage motor development at an early age. ...
... The results showed reduced cerebellar alpha power in the dyslexic group compared to normal readers at baseline and increased cerebellar alpha power in the dyslexic group upon completion of training. Previous studies suggested that the cerebellum is a potential biomarker of dyslexia, which can involve both phonological difficulties and sensorimotor deficits [70][71][72][73]. In addition, the cerebellum plays a fundamental role in motor functioning as well as cognition [74]. ...
... It is known that reading strongly depends on timing ability [146]. Moreover, the cerebellum plays a fundamental role in language [76] through (among other things) its projections with frontal and prefrontal areas [4], and its dysfunction is considered a potential biomarker for dyslexia [70][71][72][73]. It can therefore be inferred that QMT enhances cortical and cerebellar functional synchronization in individuals with dyslexia, which leads to improved timing ability that, in turn, positively affects reading skills (Figure 3). ...
In this overview, we discuss the internal and external environmental factors associated with cognitive and psycho-emotional well-being in the context of physical activity and Mindful Movement. Our key argument is that improved cognitive and emotional functions associated with mental well-being can be achieved by an external, Mindful Movement-based environment training called Quadrato Motor Training (QMT). QMT is a structured sensorimotor training program aimed at improving coordination, attention, and emotional well-being through behavioral, electrophysiological, neuroanatomical, and molecular changes. In accordance with this argument, we first describe the general neurobiological mechanisms underpinning emotional states and emotion regulation. Next, we review the relationships between QMT, positive emotional state, and increased emotion regulation, and discuss the neurobiological mechanisms underlying these relationships. We consider the relationships between motion, emotion, and cognition, and highlight the need for integrated training paradigms involving these three trajectories. Such training paradigms provide cognitively engaging exercises to improve emotion regulation, which in turn affects adaptive behaviors. Finally, we address the broader implications of improving cognitive and emotional functioning through Mindful Movement training for environmental research and public health.
... The known connectivity of the cerebellum with contralateral cerebral regions necessarily raises the question of whether damage to the left or right side of the cerebellum might result in deficits in attention/spatial processing or language (respectively). Although there is a good deal of evidence that language functions are more lateralized to the right cerebellum [for reviews see 15,16], the role of the left cerebellum in attention and spatial functions is less established [e.g., [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. ...
Each cerebellar hemisphere projects to the contralateral cerebral hemisphere. Previous research suggests a lateralization of cognitive functions in the cerebellum that mirrors the cerebral cortex, with attention/visuospatial functions represented in the left cerebellar hemisphere, and language functions in the right cerebellar hemisphere. Although there is good evidence supporting the role of the right cerebellum with language functions, the evidence supporting the notion that attention and visuospatial functions are left lateralized is less clear. Given that spatial neglect is one of the most common disorders arising from right cortical damage, we reasoned that damage to the left cerebellum would result in increased spatial neglect-like symptoms, without necessarily leading to an official diagnosis of spatial neglect. To examine this disconnection hypothesis, we analyzed neglect screening data (line bisection, cancellation, figure copying) from 20 patients with isolated unilateral cerebellar stroke. Results indicated that left cerebellar patients (n = 9) missed significantly more targets on the left side of cancellation tasks compared to a normative sample. No significant effects were observed for right cerebellar patients (n = 11). A lesion overlap analysis indicated that Crus II (78% overlap), and lobules VII and IX (66% overlap) were the regions most commonly damaged in left cerebellar patients. Our results are consistent with the notion that the left cerebellum may be important for attention and visuospatial functions. Given the poor prognosis typically associated with neglect, we suggest that screening for neglect symptoms, and visuospatial deficits more generally, may be important for tailoring rehabilitative efforts to help maximize recovery in cerebellar patients.
... 270). Evidence supporting this conceptualization (of functional interactions between motor control systems, language and reading) can be found not only in neuropsychological test findings that highlight poor cerebellar processing among many children affected by dyslexia [51,52] (for reviews, see [53,54]), but also from neurophysiological studies [55,56] (for reviews see [57,58]). Eckert and colleagues [59], for example, reported decreased right cerebellar volume among dyslexics compared to controls; this abnormality was correlated with difficulties in reading, spelling, and language processing. Thus, the involvement of the cerebellum in language seems to be well-established. ...
Developmental dyslexia is a common complex neurodevelopmental disorder. Many theories and models tried to explain its symptomatology and find ways to improve poor reading abilities. The aim of this scoping review is to summarize current findings and several approaches and theories, focusing on the interconnectedness between motion, emotion and cognition and their connection to dyslexia. Consequently, we present first a brief overview of the main theories and models regarding dyslexia and its proposed neural correlates, with a particular focus on cerebellar regions and their involvement in this disorder. After examining different types of intervention programs and remedial training, we highlight the effects of a specific structured sensorimotor intervention named Quadrato Motor Training (QMT). QMT utilizes several cognitive and motor functions known to be relevant in developmental dyslexia. We introduce its potential beneficial effects on reading skills, including working memory, coordination and attention. We sum its effects ranging from behavioral to functional, structural and neuroplastic, especially in relation to dyslexia. We report several recent studies that employed this training technique with dyslexic participants, discussing the specific features that distinguish it from other training within the specific framework of the Sphere Model of Consciousness. Finally, we advocate for a new perspective on developmental dyslexia integrating motion, emotion and cognition to fully encompass this complex disorder.
... As for the morphological abnormality characterizing DD, a meta-analysis of voxel-based morphometry (VBM) studies found consistently reduced gray matter volume in DD in the right superior temporal gyrus and left superior temporal sulcus (Richlan et al., 2013). Structural and functional anomalies of the cerebellum, both on the left and on the right, are also consistently reported for DD children and adults, especially in the anterior lobe and the lobule VI which are known sensorimotor and cognitive territories of the cerebellum (Pernet et al., 2009;Stoodley & Stein, 2011, 2013. Although the specific contribution of the cerebellum to dyslexia has yet to be determined, it may interconnect with the reading network and, once affected, would then lead to abnormality throughout that network (Stoodley, 2016, pp. ...
Developmental dyslexia (DD) and developmental coordination disorder (DCD) are two common neurodevelopmental disorders with a high co-occurrence rate. This led several authors to postulate that the two disorders share, at least partially, similar neural underpinning. However, even though several studies examined brain differences between typically developing (TD) children and children with either DD or DCD, no previous study directly compared DD, DCD and children with both disorders (COM) using neuroimaging. We acquired structural and resting-state functional MRI images of 136 children (TD = 42, DD = 45, DCD = 20, COM = 29). Difference between TD children and the other groups was assessed using univariate analysis of structural indexes including grey and white matter volumes and functional indexes quantifying activity (fraction of the amplitude of the low frequency fluctuations), local and global connectivity. Regional differences in structural and functional brain indexes were then used to train machine learning models to discriminate among DD, DCD and COM and to find the most discriminant regions. While no imaging index alone discriminated between the three groups, grouping grey and white matter volumes (structural model) or activity, local and global connectivity (functional model) made possible to discriminate among the DD, DCD and COM groups. The most important discrimination was obtained using the functional model, with regions in the cerebellum and the temporal lobe being the most discriminant for DCD and DD children, respectively. Results further showed that children with both DD and DCD have subtle but identifiable brain differences that can only be captured using several imaging indexes pertaining to both brain structure and function.
... " Conversely, P20 appreciates that "for folks with cognitive disabilities that make processing in real time a little bit more challenging, we're able to record stuff really quick and easy." Thus, meeting recordings can increase efficiency while also providing crucial access for individuals who process meetings more slowly, such as those with dyslexia [59,60] or ADHD [20,48]. ...
Workplace bias creates negative psychological outcomes for employees, permeating the larger organization. Workplace meetings are frequent, making them a key context where bias may occur. Video conferencing (VC) is an increasingly common medium for workplace meetings; we therefore investigated how VC tools contribute to increasing or reducing bias in meetings. Through a semi-structured interview study with 22 professionals, we found that VC features push meeting leaders to exercise control over various meeting parameters, giving leaders an outsized role in affecting bias. We demonstrate this with respect to four core VC features -- user tiles, raise hand, text-based chat, and meeting recording -- and recommend employing at least one of two mechanisms for mitigating bias in VC meetings -- 1) transferring control from meeting leaders to technical systems or other attendees and 2) helping meeting leaders better exercise the control they do wield.
... Many students with dyslexia have multiple deficits other than phonological deficits [4][5][6][7][8]. Of these accused deficits are visual perceptual processing deficits [9], auditory processing deficits [10], multisensory spatial attention deficits [11], as well as cerebellar dysfunction [12]. ...
Background
Dyslexia is characterized by difficulties in spelling and reading. The aim of this study is to identify domains of cognitive strength and weakness of students with dyslexia and to study the effect of an especially designed computerized training program on their reading abilities. This study was conducted on 2nd-grade primary school students in Asyut city, Egypt ( n = 560). Identification of students with dyslexia was done using Arabic Reading Achievement test and a newly constructed computerized Arabic Cognitive Abilities diagnostic battery for Reading (CADB-R). Training was applied using a newly constructed Computerized Cognitive abilities training battery for reading (CATB-R).
Results
The prevalence of dyslexia was 13.9% ( N = 52/373), and it was higher among girls (15.8%) than boys (11.7%). After application of the training program, there was a significant increase in post-training mean scores of CADB-R score in their total and all sub-items.
Conclusions
All struggling readers should be included in well-tailored research-based rehabilitation programs.
Clinical trial registration Training Second-grade Dyslexic Students Using a Computerized Program in Assiut, Egypt (Dyslexia), NCT04642859, 12 November 2020. URL: https://register.clinicaltrials.gov/prs/app/action/Status?uid=U000495F&ts=10&sid=S000AD3G&cx=20acrp
... The model was divided into ten isotropic layers representing air, scalp, skin, skull, dura mater, arachnoid, sub-arachnoid or cerebrospinal fluid (CSF), pia mater, gray matter and the white matter ( Table 1). The μECoG electrode design was constructed with typical parameters ( Table 2) commonly used in commercially available 8 × 8 arrays for animal experiments [14,15]. The contacts were 100 μm in diameter with a pitch of 500 μm (Figs. 1 & 2) placed on a polyimide substrate with a thickness of 20 μm. ...
Background
Electrocorticography (ECoG) arrays are commonly used to record the brain activity both in animal and human subjects. There is a lack of guidelines in the literature as to how the array geometry, particularly the via holes in the substrate, affects the recorded signals. A finite element (FE) model was developed to simulate the electric field generated by neurons located at different depths in the rat brain cortex and a micro ECoG array (μECoG) was placed on the pia surface for recording the neural signal. The array design chosen was a typical array of 8 × 8 circular (100 μm in diam.) contacts with 500 μm pitch. The size of the via holes between the recording contacts was varied to see the effect.
Results
The results showed that recorded signal amplitudes were reduced if the substrate was smaller than about four times the depth of the neuron in the gray matter. The signal amplitude profiles had dips around the via holes and the amplitudes were also lower at the contact sites as compared to the design without the holes; an effect that increased with the hole size. Another noteworthy result is that the spatial selectivity of the multi-contact recordings could be improved or reduced by the selection of the via hole sizes, and the effect depended on the distance between the neuron pair targeted for selective recording and its depth.
Conclusions
The results suggest that the via-hole size clearly affects the recorded neural signal amplitudes and it can be leveraged as a parameter to reduce the inter-channel correlation and thus maximize the information content of neural signals with μECoG arrays.
... More broadly, cerebellar function in dyslexia has been the topic of many investigations. Indeed, past works have repeatedly highlighted functional and structural abnormalities of the cerebellum in DYS samples [71][72][73][74]. Therefore, observing RSFC reduction with the GMFA in cerebellar regions was not surprising. ...
Aim:
Handwriting abilities in children with dyslexia (DYS) are not well documented in the current literature, and the presence of graphomotor impairment in addition to spelling impairment in dyslexia is controversial. Using resting-state functional connectivity (RSFC), the present study aims to answer the following question: are there markers of graphomotor impairment at rest in DYS children?
Method:
The participants were children with DYS and typically developing (TD) children (n = 32) from French-speaking primary schools (Mage = 9.3 years). The behavioural evaluation consisted of spelling and handwriting measures. Participants underwent a resting-state fMRI scan.
Results:
Analyses of RSFC focused on a brain region responsible for graphomotor processes-the graphemic/motor frontal area (GMFA). The RSFC between the GMFA and all other voxels of the brain was measured. Whole-brain ANOVAs were run to compare RSFC in DYS and TD children. The results demonstrated reduced RSFC in DYS compared to TD between the GMFA and brain areas involved in both spelling processes and motor-related processes.
Conclusions:
For the first time, this study highlighted a disruption of the writing network in DYS. By identifying functional markers of both spelling and handwriting deficits at rest in young DYS participants, this study supports the presence of graphomotor impairment in dyslexia.
... One theory of the etiology of dyslexia is the cerebellar hypothesis, which implicates cerebellar dysfunction in deficits of procedural learning and reading fluency ( Nicolson et al., 2001 ;Nicolson and Fawcett, 2007 ;Stoodley and Stein, 2011 ). To this end, the contributions of the superior (SCP), inferior (ICP), and middle (MCP) cerebellar peduncles to reading have been investigated. ...
Reading involves the functioning of a widely distributed brain network, and white matter tracts are responsible for transmitting information between constituent network nodes. Several studies have analyzed fiber bundle microstructural properties to shed insights into the neural basis of reading abilities and disabilities. Findings have been inconsistent, potentially due to small sample sizes and varying methodology. To address this, we analyzed a large data set of 686 children ages 5-18 using state-of-the-art neuroimaging acquisitions and processing techniques. We searched for associations between fractional anisotropy (FA) and single-word and single-nonword reading skills in children with diverse reading abilities across multiple tracts previously thought to contribute to reading. We also looked for group differences in tract FA between typically reading children and children with reading disabilities. FA of the white matter increased with age across all participants. There were no significant correlations between overall reading abilities and tract FAs across all children, and no significant group differences in tract FA between children with and without reading disabilities. There were associations between FA and nonword reading ability in older children (ages 9 and above). Higher FA in the right superior longitudinal fasciculus (SLF) and left inferior cerebellar peduncle (ICP) correlated with better nonword reading skills. These results suggest that letter-sound correspondence skills, as measured by nonword reading, are associated with greater white matter coherence among older children in these two tracts, as indexed by higher FA.
... was a major contributor to this finding, describing the involvement of the cerebellum in cognitive processing and its connection to the hemispheric and cortical points that aid in cognitive processing, as well as the connection of the cerebellar worm to structures. of the parietal system including the hippocampus and amygdala(Baillieux, 2008;Lagarde, 2009;Misciagna, 2012;Stoodley & Stein, 2009;Vicari, 2012).Based on the above findings, neuroimaging studies have highlighted a possible involvement of the cerebellum with dyslexia. Indeed, in many studies of dyslexic individuals, a cerebellar symmetry and a high concentration of gray matter have been observed, suggesting cerebellar damage. ...
The term learning disabilities refers to a complex and multidimensional phenomenon that affects many thousands of students. Due to the rich symptomatology of learning difficulties and the increased differences between individuals, it has not been possible to analyze all cases exclusively from the perspective of the neuropsychological approach. Aim. The aim of this study was to present research conducted in the context of theories on the brain function of people with learning disabilities. Supporting the hypothesis of brain dysfunction. Methodology: Literature review was carried out in the web, which referred to researches on Special Learning Disabilities and the brain function associated with them. Results: Review of the literature highlighted key points of the relationship between learning difficulties and brain function. Brain dysfunction and the cognitive functions produced emerged as one of the key factors involved in learning disabilities. Many of the theories developed around the problems of children with learning disabilities have focused on specific areas of the brain that may be dysfunctional. Conclusions: The difficulty of locating obvious brain damage in individuals who have been characterized as dyslexic leads to the strengthening of the hypothesis of the existence of a slight or minimal brain damage that cannot be easily diagnosed and strengthens the hypothesis of an unexplained brain damage that could be heterogeneous groups of learning disabilities.
... Traditionally, cerebellar function has been associated with movement control and coordination, but recently it has emerged as an important role in higher cognitive functions such as attention, memory, learning, executive control, language and visual spatial functions. Schmahmann (1996) was a major contributor to this finding, describing the involvement of the cerebellum in cognitive processing and its connection to the hemispheric and cortical points that aid in cognitive processing, as well as the connection of the cerebellar worm to structures. of the parietal system including the hippocampus and amygdala (Baillieux, 2008;Lagarde, 2009;Misciagna, 2012;Stoodley& Stein, 2009;Vicari, 2012). ...
... Therefore, hyperactivation in the right cerebellum in readers with DD suggests that they may use it as a compensation for their deficient phonological processing, while hypoactivation in the left cerebellum may suggest reduced error monitoring in readers with DD. The finding of neurological alterations in the cerebellum is consistent with the previous findings of cerebellar deficit (Menghini et al., 2006;Yang et al., 2013) for which, some researchers argued that impaired articulatory motor control in the cerebellum leads to reading impairment (Nicolson et al., 2001;Stoodley and Stein, 2011). It also should be noticed that the cerebellum showed divergent patterns in structural studies and functional studies. ...
Brain abnormalities in the reading network have been repeatedly reported in individuals with developmental dyslexia (DD); however, it is still not totally understood where and why the structural and functional abnormalities are consistent/inconsistent across languages. In the current multimodal meta-analysis, we found convergent structural and functional alterations in the left superior temporal gyrus across languages, suggesting a neural signature of DD. We found greater reduction in grey matter volume and brain activation in the left inferior frontal gyrus in morpho-syllabic languages (e.g. Chinese) than in alphabetic languages, and greater reduction in brain activation in the left middle temporal gyrus and fusiform gyrus in alphabetic languages than in morpho-syllabic languages. These language differences are explained as consequences of being DD while learning a specific language. In addition, we also found brain regions that showed increased grey matter volume and brain activation, presumably suggesting compensations and brain regions that showed inconsistent alterations in brain structure and function. Our study provides important insights about the etiology of DD from a cross-linguistic perspective with considerations of consistency/inconsistency between structural and functional alterations.
... Traditionally, cerebellar function has been associated with movement control and coordination, but recently it has emerged as an important role in higher cognitive functions such as attention, memory, learning, executive control, language and visual spatial functions. Schmahmann (1996) was a major contributor to this finding, describing the involvement of the cerebellum in cognitive processing and its connection to the hemispheric and cortical points that aid in cognitive processing, as well as the connection of the cerebellar worm to structures. of the parietal system including the hippocampus and amygdala (Baillieux, 2008;Lagarde, 2009;Misciagna, 2012;Stoodley& Stein, 2009;Vicari, 2012). ...
Introduction: that affects many thousands of students. Due to the rich symptomatology of learning difficulties and the increased differences between the perspective of the neuropsychological approach. Aim. The aim of this study was to present research conducted in the context of theories on the brain function of people with lea Methodology: Learning Disabilities and the brain function associated with them. Results: and brain function. Brain dysfunction and the cognitive functions produced emerged as one of the key factors involved in learning disabilities. Many of the theories developed around the problems of children with learning disabilities have focused on s Conclusions: characterized as dyslexic leads to the strengthening of the hypothesis of the existence of a slight or minimal b unexplained brain damage that could be heterogeneous groups of learning disabilities.
... Traditionally, cerebellar function has been associated with movement control and coordination, but recently it has emerged as an important role in higher cognitive functions such as attention, memory, learning, executive control, language and visual spatial functions. Schmahmann (1996) was a major contributor to this finding, describing the involvement of the cerebellum in cognitive processing and its connection to the hemispheric and cortical points that aid in cognitive processing, as well as the connection of the cerebellar worm to structures. of the parietal system including the hippocampus and amygdala [3,4,[18][19][20]. ...
... Traditionally, the cerebellum is considered to be important for the timing and coordination of motor outputs and motor learning (Glickstein, Strata, & Voogd, 2009;Glickstein, Sultan, & Voogd, 2011). However, more recent research has highlighted a role in a diverse array of cognitive, affective, and perceptual processes, including language, working memory, executive control, emotion and motion perception (Adamaszek et al., 2017;Baumann et al., 2015;Bellebaum & Daum, 2007;Marvel & Desmond, 2010;Sacchetti, Scelfo, & Strata, 2009;Schmahmann, Guell, Stoodley, & Halko, 2019;Schmahmann & Sherman, 1998;Stoodley, MacMore, Makris, Sherman, & Schmahmann, 2016;Stoodley & Schmahmann, 2009a;Stoodley & Stein, 2011). The role of the cerebellum in cognition is supported by anatomical evidence demonstrating connections from the ventral dentate nucleus to non-motor regions of posterior parietal and prefrontal cortex (Clower, West, Lynch, & Strick, 2001;Dum & Strick, 2003;Strick, Dum, & Fiez, 2009). ...
The current study represents the first comprehensive examination of spatial, temporal and sustained attention following cerebellar damage. Results indicated that, compared to controls, cerebellar damage resulted in a larger cueing effect at the longest SOA – possibly reflecting a slowed the onset of inhibition of return (IOR) during a reflexive covert attention task, and reduced the ability to detect successive targets during an attentional blink task. However, there was little evidence to support the notion that cerebellar damage disrupted voluntary covert attention or the sustained attention to response task (SART). Lesion overlay data and supplementary voxel-based lesion symptom mapping (VLSM) analyses indicated that impaired performance on the reflexive covert attention and attentional blink tasks were related to damage to Crus II of the left posterior cerebellum. In addition, subsequent analyses indicated our results are not due to either general motor impairments or to damage to the deep cerebellar nuclei. Collectively these data demonstrate, for the first time, that the same cerebellar regions may be involved in both spatial and temporal visual attention.
... The disparate symptoms of dyslexia, involving the perceptual, cognitive, and motor domains, demands an integrative account of the etiopathogenesis of this condition. The cerebellar dysfunction hypothesis highlights the role of the cerebellum in the automatization of the varied processes underlying reading (Nicolson and Fawcett, 1990;Fawcett et al., 1996;Nicolson et al., 2001; for a review see Stoodley and Stein, 2011) . Likewise, "sensory theories" of dyslexia argue for a wider interpretation of the phonological deficit theory, relying on auditory, visual, and motor deficits (Goswami, 2014) . ...
Developmental dyslexia is a heterogeneous condition entailing problems with reading and spelling. Several genes have been linked or associated to the disease, many of which contribute to the development and function of brain areas that are important for auditory and phonological processing. Nonetheless, a clear link between genes, the brain, and the symptoms of dyslexia is still pending. The goal of this paper is contributing to bridge this gap. With this aim, we have focused on how the dyslexic brain fails to process speech sounds and reading cues. We have adopted an oscillatory perspective, according to which dyslexia results from a deficient integration of different brain rhythms during reading/spellings tasks. Moreover, we show that some candidates for this condition are related to brain rhythms. This approach should help gain a better understanding of the aetiology and the clinical presentation of developmental dyslexia, but also achieve an earlier and more accurate diagnosis of the disease.
... . Because of the strong link between reading and motor control (Kulp & Schmidt, 1996;Viholainen et al., 2006), it is possible that the automatization of reading is also cerebellar dependent (Rae et al., 2002;Stoodley & Stein, 2011;Vlachos, Papathanasiou, & Andreou, 2007). ...
Reading is a critical neurodevelopmental skill for school‐aged children, which requires a distributed network of brain regions including the cerebellum. However, we do not know how functional connectivity between the cerebellum and other brain regions contributes to reading. Here we used resting‐state functional connectivity to understand the cerebellum’s role in decoding, reading speed, and comprehension in a group of struggling readers (RD) and a group of adolescents and children with typical reading abilities (TD). We observed an increase in functional connectivity between the sensorimotor network and the left angular gyrus, left lateral occipital cortex, and right inferior frontal gyrus in the RD group relative to the TD group. Additionally, functional connectivity between the cerebellum network and the precentral gyrus was decreased and was related to reading fluency in the RD group. Seed‐based analysis revealed increased functional connectivity between Crus 1, lobule 6, and lobule 8 of the cerebellum and brain regions related to the default mode network and the motor system for the RD group. We also found associations between reading performance and the functional connectivity between lobule 8 of the cerebellum and the left angular gyrus for both groups, with stronger relationships in the TD group. Specifically, the RD group displayed a positive relationship between functional connectivity, whereas the TD group displayed the opposite relationship. These results suggest that the cerebellum is involved in multiple components of reading performance and that functional connectivity differences observed in the RD group may contribute to poor reading performance.
... Aside from academic difficulties, children with SLD have often been found to exhibit clumsy and awkward movements while performing physical exercise (5). They show deficits in movement performance, such as in gross motor (6), fine motor (7), balance (8,9) and functional skills (10). Insights into movement and functional performance of children with SLD are essential for health professionals and teachers to manage movement difficulty in these children. ...
Various standardised assessment tools have been used to evaluate children with disabilities. However, assessment tools that provide information on the movement and function of children with specific learning disabilities (SLD) are still limited. This article provides a narrative review of the characteristics of five movement and/or function assessment tools. The strengths and limitations of the tools will be highlighted. Empirical studies on the assessment tools used are reviewed based on three criteria: (i) standardised tools; (ii) assessment of movement and/or function; (iii) applicability to children with SLD ranging from 4-17 years of age and widely used in practice. The following instruments have been included as they have been found to fulfil the criteria: (i) the Bruininks-Oseretsky test of motor proficiency-2 (BOT-2); (ii) the movement assessment battery for children-2 (MABC-2); (iii) the pediatric balance scale (PBS); (iv) the Vineland adaptive behaviour scale-II (VABS-II) and (v) the pediatric evaluation of disability inventory-computerised adaptive test (PEDI-CAT). The article presents the characteristics, strengths and limitations of five standardised assessment tools that are currently in use, which measure the movement and/or function of children with SLD. This article concludes with a discussion of recommendations for the best approaches to evaluating the movement and functional abilities of children with SLD.
... In the early nineties, Nicolson and Fawcett (1990) proposed the deficit in automatisation hypothesis, which stipulates that children with dyslexia would struggle to make any new skill automatic. Throughout their work, Fawcett and Nicolson gathered evidence that children and adults with dyslexia demonstrate signs of cerebellar impairment (Fawcett & Nicolson, 1992;Fawcett, Nicolson, & Dean, 1996;Nicolson, Fawcett, & Dean, 2001) and those signs were confirmed with fMRI studies (Stoodley & Stein, 2011). However, these motor theories of dyslexia have been disputed within the literature. ...
Several studies have demonstrated that children with dyslexia frequently show poor and slow handwriting skills. It is not clear whether these difficulties are a consequence of their spelling deficit or if they arise from graphomotor difficulties. The present study aims to test the hypothesis of the presence of handwriting difficulties in dyslexia, through the investigation of the impact of graphic and orthographic complexity of words on writing. Participants were all monolingual French-speaking children. Twenty-three children with dyslexia (DYS) were compared to two groups of typically developing children: 23 chronological-age (CA) matched children and 23 spelling-age (SA) matched children. They were assessed on a single-word dictation task of 40 words on a digital tablet. The target words varied in orthographic complexity and in graphic complexity (simple vs. difficult). This task was scored on spelling accuracy, handwriting quality and handwriting speed. General Linear Mixed Model analyses revealed no global differences between the three groups for handwriting quality. However, the DYS children were more impacted by the graphic complexity of words than both the CA and SA children. These findings support the idea that children with dyslexia struggle with the graphomotor aspects of writing and have potential implications for educational and clinical supports.
... Traditionally, the cerebellum is considered to be important for the timing and coordination of motor outputs and motor learning (Glickstein, Strata et al., 2009;Glickstein, Sultan et al., 2011). However, more recent research has highlighted a role in a diverse array of cognitive, affective, and perceptual processes, including language, working memory, executive control, emotion and motion perception (Adamaszek, D'Agata et al., 2017;Baumann, Borra et al., 2015;Marvel & Desmond, 2010;Sacchetti, Scelfo et al., 2009;Schmahmann, Guell et al., 2019;Schmahmann & Sherman, 1998;Stoodley, MacMore et al., 2016;Stoodley & Schmahmann, 2009;Stoodley & Stein, 2011). ...
The current study represents the first comprehensive examination of spatial, temporal and sustained attention following cerebellar damage. Results indicated that, compared to controls, cerebellar damage eliminated the onset of inhibition of return (IOR) during the reflexive covert attention task, and reduced the ability to detect successive targets during an attentional blink task. However, cerebellar damage had no effect on voluntary covert attention or the sustained attention to response task (SART). Lesion overlay analysis indicated that impaired performance on IOR and the attentional blink were associated with damage to Crus II and lobule VII (tuber) and VIII (pyramis) of the left posterior cerebellum. Critically, subsequent analyses indicated our results are not due to either general motor impairments or to damage to the deep cerebellar nuclei. Collectively these data demonstrate, for the first time, that the same cerebellar regions are involved in both spatial and temporal visual attention. Furthermore, these data suggest that damage to the cerebellum may induce a form of attentional dysmetria, such that performance suffers under conditions in which the rapid deployment of attention (either spatial or temporal) is required.
... The lower results of poorer readers on rapid naming tasks (RAN; Wolf & Bowers, 2000) may point to a sequence learning deficit, as sequential processing is also involved in RAN tasks (Bennett et al., 2008). Furthermore, the cerebellar theory (Nicolson, Fawcett, & Dean, 2001) stresses the contribution of the cerebellum to central-auditory functions, speech perception, speech timing, and, hence, phonological awareness (Stoodley & Stein, 2011). ...
Schools are introducing more and more non-evidence-based methods in dyslexia therapy. The aim of the study is to verify whether the novel method – Warnke Method can be regarded as a useful tool in dyslexia therapy in Polish children. The research group consisted of 37 pupils, between 10 and 12 years, diagnosed with developmental dyslexia. Participants were assessed at pretest on literacy and phonological processing and tasks measuring central auditory and visual processing with Warnke Method tools. Subsequently, each child underwent 20 training sessions of Warnke Method. Afterwards, children were assessed with posttest measures. Results showed that phonological processing served as a mediator in relationship between central auditory and visual processing and reading and writing skills. Significant improvement was observed with regard to central auditory and visual processing, phonological processing, as well as reading and writing skills. Furthermore, improvement was seen in students' grades of Polish language and literature classes.
... The cerebellum presents a diversity of functions, from motor behaviors involving coordination, learning and balance [261][262][263][264] to non-motor behaviors such as cognition, emotion, language, and spatial navigation [4,[265][266][267]. This diversity implies that cerebellar dysfunction is associated with several diseases, ranging from neurological conditions such as ataxia, dystonia, and tremor [268] to neuropsychiatric disorders such as dyslexia, schizophrenia [269], mood disorder and anxiety [270], attention deficit hyperactivity disorder [271], and autism spectrum disorder [272,273]. As discussed in this review, glial cells participate in numerous events of cerebellar development and physiology; however, studies regarding glial alterations in pathologies related to cerebellar function are still scarce. ...
Astrocytes, initially described as merely support cells, are now known as a heterogeneous population of cells actively involved in a variety of biological functions such as: neuronal migration and differentiation; regulation of cerebral blood flow; metabolic control of extracellular potassium concentration; and modulation of synapse formation and elimination; among others. Cerebellar glial cells have been shown to play a significant role in proliferation, differentiation, migration, and synaptogenesis. However, less evidence is available about the role of neuron-astrocyte interactions during cerebellar development and their impact on diseases of the cerebellum. In this review, we will focus on the mechanisms underlying cellular interactions, specifically neuron-astrocyte interactions, during cerebellar development, function, and disease. We will discuss how cerebellar glia, astrocytes, and Bergmann glia play a fundamental role in several steps of cerebellar development, such as granule cell migration, axonal growth, neuronal differentiation, and synapse formation, and in diseases associated with the cerebellum. We will focus on how astrocytes and thyroid hormones impact cerebellar development. Furthermore, we will provide evidence of how growth factors secreted by glial cells, such as epidermal growth factor and transforming growth factors, control cerebellar organogenesis. Finally, we will argue that glia are a key mediator of cerebellar development and that identification of molecules and pathways involved in neuron-glia interactions may contribute to a better understanding of cerebellar development and associated disorders.
... The Cerebellar Deficit Theory of Reading Disorder In recent decades, it has been suggested that subtle differences in cerebellar function may lead to generalized cognitive and behavioral differences in some individuals [25]. These differences may manifest as deficits in executive function, cognitive processing, working memory, verbal fluency, rapid automatized naming (RAN; which refers to the ability to quickly and accurately name familiar letters, numbers, colors, and objects) speed, and decreased reading proficiency [7,15,[25][26][27]. Relevant to the current work, there is evidence that suggests many individuals with reading difficulties have measurable differences in cerebellar structure and function. ...
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The nature and extent to which the cerebellum contributes to language processing is not clear. By using fMRI to examine differences in activation intensity in areas associated with motor and language processes, we advance our understanding of how this subcortical structure contributes to language and, more specifically, reading. Functional magnetic resonance imaging data was collected from two groups of adults. One group was classified as typical (proficient) readers, and the other as atypical (less proficient) readers. fMRI was used to measure cerebellar activation during silent reading and silent rapid naming tasks, which differed in degree of language and motor/articulatory processing. Regions of interest associated with motor and language processing were examined in order to compare how cerebellar activation in typical and atypical readers differed as a function of task both within and between groups. Significant differences in activation intensity were noted between individuals of typical and atypical reading proficiency in cerebellar regions associated with motor, but not language processing, during a silent word-reading condition. Additionally, readers who were less proficient showed no differences in activation between tasks in each of the regions of interest within the cerebellum. We provide evidence that, in typical readers, the cerebellum is functionally specialized for reading tasks that vary in language and articulatory processes. In accordance with prior research, we demonstrate that less-proficient adult readers show decreased functional specialization within the cerebellum during reading tasks. We also show that regions of the cerebellum associated with motor/articulatory processing are different between typical and atypically reading adults. Finally, to our knowledge, this is the first brain-imaging study to specifically examine cerebellar activation during rapid naming tasks and we discuss the implications for these findings with regard to current theoretical models that emphasize the link between reading and speech production.
... Abovementioned deficiencies in people with dyslexia have led to the cerebellar deficit hypothesis (CDH; Nicolson et al. 1995Nicolson et al. , 2001. The cerebellum is presumed to regulate processing of information from and to the cortex and other areas by forward loops (Stoodley and Stein 2011). Presumably, the anterior lobe and lobule VII of the cerebellum are involved in fine tuning and supporting processing of sensorimotor programmes, while lobules VI and VII contribute during a wide range of cognitive tasks (Stoodley and Schmahmann 2010). ...
Developmental dyslexia is commonly believed to result from a deficiency in the recognition and processing of speech sounds. According to the cerebellar deficit hypothesis, this phonological deficit is caused by deficient cerebellar function. In the current study, 26 adults with developmental dyslexia and 25 non-dyslexic participants underwent testing of reading-related skills, cerebellar functions, and MRI scanning of the brain. Anatomical assessment of the cerebellum was conducted with voxel-based morphometry. Behavioural evidence, that was indicative of impaired cerebellar function, was found to co-occur with reading impairments in the dyslexic subjects, but a causal relation between the two was not observed. No differences in local grey matter volume, nor in structure–function relationships within the cerebellum were found between the two groups. Possibly, the observed behavioural pattern is due to aberrant white matter connectivity. In conclusion, no support for the cerebellar deficit hypothesis or the presence of anatomical differences of the cerebellum in adults with developmental dyslexia was found.
Electronic supplementary material
The online version of this article (10.1007/s00221-018-5351-y) contains supplementary material, which is available to authorized users.
... showed that cerebellar activation during learning to track a novel trajectory is greatly reduced in dyslexics. Thus in summary, there is now a great deal of evidence that cerebellar function is impaired in dyslexics, and this provides yet further indirect evidence for magnocellular involvement in dyslexic problems (Stoodley & Stein, 2011). ...
Developmental dyslexia is frequently associated with phonological difficulties such as poor phonological awareness, access, or short term memory skills, that further impede the acquisition of letter-to-sound mappings. Some hypotheses suggest that phonological disorders in dyslexia are themselves caused by a more basic auditory processing deficit. Here, we review evidence showing that a high sensitivity to auditory rhythmic cues may be critical for phonological and reading development. Moreover, the brain signature of prosodic and rhythmic processing difficulties in dyslexia may reside in atypical right hemisphere synchronization to slow frequency auditory modulations, that would then generate left hemisphere-based dyslexic reading symptoms. Overall, the data presented in this chapter suggests that interventions aimed at facilitating the extraction of rhythmic and temporally regular patterns in auditory sequences could improve reading in dyslexia through the enhancement of phonological skills.
... Nicolson et al. (1999) showed that 622 cerebellar activation during learning to track a novel trajectory is greatly reduced 623 in dyslexics. Thus in summary, there is now a great deal of evidence that cerebellar 624 function is impaired in dyslexics, and this provides yet further indirect evidence for 625 magnocellular involvement in dyslexic problems (Stoodley & Stein 2011). ...
The late 19th neurological concept of dyslexia had 3 crucial elements: selectively poor reading, with unaffected other cognitive skills and a genetic background. The contemporary ‘phonological theory’ has undermined the selectivity criterion because all poor readers, dyslexic or otherwise, have phonological problems. Here I argue that the phonological theory is pitched at too high a cognitive level so that it does not illuminate the mechanisms that cause reading problems in dyslexia. Recent genetic and imaging studies have confirmed their biological basis. In children with visual reading problems there is strong evidence that they suffer impaired development of the visual magnocellular (M-) system which is vital for tracking shifts of the focus of visual attention and of eye movements. This can often be ameliorated by viewing text through deep yellow or blue filters because they can facilitate the M- system. Likewise children with phonological problems seem to suffer an analogous impairment of sound sequencing, which can be ameliorated by musical training, particularly in rhythm; whilst those with impaired motor sequencing can often be helped by motor training. Thus in dyslexics the neural sub system which is required for rapid and accurate temporal processing and is distributed throughout the brain, appears to be compromised. This system’s ‘M-’ neurones express a specific surface marker that renders them susceptible to autoimmune attack, and the rapidity with which they have to respond, makes them particularly vulnerable to lack of omega 3 long chain polyunsaturated fatty acids in the diet. But its weaknesses for temporal processing may be balanced by exceptional talents for other kinds of cognitive task.
... Third, we observed significant correlations between brain activities and linguistic evaluation scores, rather than KPS scores which represented performance status. Finally, the identified cerebro-cerebellar areas with structural and functional alterations were traditionally viewed with high language-relevancy according to previous knowledge (as discussed above) (Marien et al., 2014;Stoodley 2012;Stoodley & Schmahmann, 2009;Stoodley & Stein, 2011;Verly et al., 2014). ...
The role of cerebellum and cerebro‐cerebellar system in neural plasticity induced by cerebral gliomas involving language network has long been ignored. Moreover, whether or not the process of reorganization is different in glioma patients with different growth kinetics remains largely unknown. To address this issue, we utilized preoperative structural and resting‐state functional MRI data of 78 patients with left cerebral gliomas involving language network areas, including 46 patients with low‐grade glioma (LGG, WHO grade II), 32 with high‐grade glioma (HGG, WHO grade III/IV), and 44 healthy controls. Spontaneous brain activity, resting‐state functional connectivity and gray matter volume alterations of the cerebellum were examined. We found that both LGG and HGG patients exhibited bidirectional alteration of brain activity in language‐related cerebellar areas. Brain activity in areas with increased alteration was significantly correlated with the language and MMSE scores. Structurally, LGG patients exhibited greater gray matter volume in regions with increased brain activity, suggesting a structure–function coupled alteration in cerebellum. Furthermore, we observed that cerebellar regions with decreased brain activity exhibited increased functional connectivity with contralesional cerebro‐cerebellar system in LGG patients. Together, our findings provide empirical evidence for a vital role of cerebellum and cerebro‐cerebellar circuit in neural plasticity following lesional damage to cerebral language network. Moreover, we highlight the possible different reorganizational mechanisms of brain functional connectivity underlying different levels of behavioral impairments in LGG and HGG patients.
Reading fluency, the ability to read quickly and accurately, is a critical marker of successful reading and is notoriously difficult to improve in reading disabled populations. Despite its importance to functional literacy, fluency is a relatively under-studied aspect of reading, and the neural correlates of reading fluency are not well understood. Here, we review the literature of the neural correlates of reading fluency and rapid automatized naming (RAN), a task that is robustly related to reading speed. In a qualitative review of the neuroimaging literature, we evaluated structural and functional MRI studies of reading fluency in readers ranging in skill levels. This was followed by a quantitative activation likelihood estimate (ALE) meta-analysis of fMRI studies of reading fluency and RAN measures. We anticipated that reading speed, relative to untimed reading and reading-related tasks, would harness ventral reading pathways that are thought to enable the fast, visual recognition of words. The qualitative review showed that speeded reading taps the entire canonical reading network. The meta-analysis, which focused on in-scanner reading fluency measures, indicated a stronger role of the ventral reading pathway in fluent reading. Both reviews identified regions outside the canonical reading network that contribute to reading fluency, such as the bilateral insula and superior parietal lobule. We suggest that fluent reading engages both domain-specific reading pathways as well as domain-general regions that support overall task performance and discuss future avenues of research to expand our understanding of the neural bases of fluent reading.
The cerebellum is known to play an important role in the coordination and timing of limb movements. The present study focused on how reach kinematics are affected by cerebellar lesions to quantify both the presence of motor impairment, and recovery of motor function over time. In the current study, 12 patients with isolated cerebellar stroke completed clinical measures of cognitive and motor function, as well as a visually guided reaching (VGR) task using the Kinarm exoskeleton at baseline (∼2 weeks), as well as 6, 12, and 24-weeks post-stroke. During the VGR task, patients made unassisted reaches with visual feedback from a central 'start' position to one of eight targets arranged in a circle. At baseline, 6/12 patients were impaired across several parameters of the VGR task compared to a Kinarm normative sample (n = 307), revealing deficits in both feed-forward and feedback control. The only clinical measures that consistently demonstrated impairment were the Purdue Pegboard Task (PPT; 9/12 patients) and the Montreal Cognitive Assessment (6/11 patients). Overall, patients who were impaired at baseline showed significant recovery by the 24-week follow-up for both VGR and the PPT. A lesion overlap analysis indicated that the regions most commonly damaged in 5/12 patients (42% overlap) were lobule IX and Crus II of the right cerebellum. A lesion subtraction analysis comparing patients who were impaired (n = 6) vs. unimpaired (n = 6) on the VGR task at baseline showed that the region most commonly damaged in impaired patients was lobule VIII of the right cerebellum (40% overlap). Our results lend further support to the notion that the cerebellum is involved in both feedforward and feedback control during reaching, and that cerebellar patients tend to recover relatively quickly overall. In addition, we argue that future research should study the effects of cerebellar damage on visuomotor control from a perception-action theoretical framework to better understand how the cerebellum works with the dorsal stream to control visually guided action.
Workplace bias creates negative psychological outcomes for employees, permeating the larger organization. Workplace meetings are frequent, making them a key context where bias may occur. Video conferencing (VC) is an increasingly common medium for workplace meetings; we therefore investigated how VC tools contribute to increasing or reducing bias in meetings. Through a semi-structured interview study with 22 professionals, we found that VC features push meeting leaders to exercise control over various meeting parameters, giving leaders an outsized role in affecting bias. We demonstrate this with respect to four core VC features---user tiles, raise hand, text-based chat, and meeting recording---and recommend employing at least one of two mechanisms for mitigating bias in VC meetings---1) transferring control from meeting leaders to technical systems or other attendees and 2) helping meeting leaders better exercise the control they do wield.
Phonemic processing skills are impaired both in children and adults with dyslexia. Since phoneme representation development is based on articulatory gestures, it is likely that these gestures influence oral reading-related skills as assessed through phonemic awareness tasks. In our study, fifty-two young dyslexic adults, with and without motor impairment, and fifty-nine skilled readers performed reading, phonemic awareness, and articulatory tasks. The two dyslexic groups exhibited slower articulatory rates than skilled readers and the comorbid dyslexic group presenting with an additional difficulty in respiratory control (reduced speech proportion and increased pause duration). Two versions of the phoneme awareness task (PAT) with pseudoword strings were administered: a classical version under time pressure and a delayed version in which access to phonemic representations and articulatory programs was facilitated. The two groups with dyslexia were outperformed by the control group in both versions. Although the two groups with dyslexia performed equally well on the classical PAT, the comorbid group performed significantly less efficiently on the delayed PAT, suggesting an additional contribution of articulatory impairment in the task for this group. Overall, our results suggest that impaired phoneme representations in dyslexia may be explained, at least partially, by articulatory deficits affecting access to them.
Brain abnormalities in the reading network have been repeatedly reported in individuals with developmental dyslexia (DD); however, it is still not totally understood where the structural and functional abnormalities are consistent/inconsistent across languages. In the current multimodal meta-analysis, we found convergent structural and functional alterations in the left superior temporal gyrus across languages, suggesting a neural signature of DD. We found greater reduction in grey matter volume and brain activation in the left inferior frontal gyrus in morpho-syllabic languages (e.g. Chinese) than in alphabetic languages, and greater reduction in brain activation in the left middle temporal gyrus and fusiform gyrus in alphabetic languages than in morpho-syllabic languages. These language differences are explained as consequences of being DD while learning a specific language. In addition, we also found brain regions that showed increased grey matter volume and brain activation, presumably suggesting compensations and brain regions that showed inconsistent alterations in brain structure and function. Our study provides important insights about the etiology of DD from a cross-linguistic perspective with considerations of consistency/inconsistency between structural and functional alterations.
Individuals with dyslexia present with reading-related deficits including inaccurate and/or less fluent word recognition and poor decoding abilities. Slow reading speed and worse text comprehension can occur as secondary consequences of these deficits. Reports of visual symptoms such as atypical eye movements during reading gave rise to a search for these deficits’ underlying mechanisms. This study sought to replicate established behavioral deficits in reading and cognitive processing speed while investigating their underlying mechanisms in more detail by developing a comprehensive profile of eye movements specific to reading in adult dyslexia. Using a validated standardized reading assessment, our findings confirm a reading speed deficit among adults with dyslexia. We observed different eye movements in readers with dyslexia across numerous eye movement metrics including the duration of a stop (i.e., fixation), the length of jumps (i.e., saccades), and the number of times a reader’s eyes expressed a jump atypical for reading. We conclude that individuals with dyslexia visually sample written information in a laborious and more effortful manner that is fundamentally different from those without dyslexia. Our findings suggest a mix of aberrant cognitive linguistic and oculomotor processes being present in adults with dyslexia.
This chapter proposes a review of neuropsychologic and behavior findings in pediatric pathologies of the cerebellum, including cerebellar malformations, pediatric ataxias, cerebellar tumors, and other acquired cerebellar injuries during childhood. The chapter also contains reviews of the cerebellar mutism/posterior fossa syndrome, reported cognitive associations with the development of the cerebellum in typically developing children and subjects born preterm, and the role of the cerebellum in neurodevelopmental disorders such as autism spectrum disorders and developmental dyslexia. Cognitive findings in pediatric cerebellar disorders are considered in the context of known cerebellocerebral connections, internal cellular organization of the cerebellum, the idea of a universal cerebellar transform and computational internal models, and the role of the cerebellum in specific cognitive and motor functions, such as working memory, language, timing, or control of eye movements. The chapter closes with a discussion of the strengths and weaknesses of the cognitive affective syndrome as it has been described in children and some conclusions and perspectives.
The engagement of the cerebellum VI in reading was reported in both typically developing and dyslexic readers. However, it is still not clear how the cerebellum VI contributes to reading. Here we have examined the correlation of intrinsic cerebro-cerebellar functional connectivity with two critical reading-related skills—phonological awareness (PA) and rapid automatized naming (RAN)—with fMRI technology. Specifically, we tested the hypothesis that the cerebellum may contribute to reading either by phonological skills or by automatizing skills. We chose the left and right cerebellum VI as ROIs, and we calculated the intrinsic cerebro-cerebellar functional connectivity during a resting state. We further explored whether and how cerebro-cerebellar resting state functional connectivity (RSFC) is associated with individuals’ reading-related skills including PA and RAN. The results showed that the functional connectivity between the left supramarginal gyrus and bilateral cerebellum VI was related to RAN, and the connectivity between the left insula and right cerebellum VI was related to PA. However, the effect of PA did not survive after the RAN was regressed out. Control analyses further confirmed that it was the intrinsic cerebro-cerebellar functional connectivity rather than the local cerebellar functionality that associated with phonological awareness ability and rapid automatized naming ability. For the first time, the relationship between cerebro-cerebellar resting state functional connectivity and specific reading-related skills has been explored, and this has deepened our understanding of the way the cerebellum VI is involved in reading.
The Functional Coordination approach of reading acquisition claims that beginning readers draw on established cognitive functions that are (1) recruited, (2) modified, and (3) coordinated to create a cognitive procedure for reading text, which forms the basis of subsequent (4) automatization. In this chapter we will focus on visual functions and how they are modified and coordinated with other cognitive functions involved in a reading specific cognitive procedure. Evidence relating to the emerging prevalence of analytic processing in letter perception is discussed. It is argued that the process of learning to read does not lead to a loss (recycling) of perceptual skills, but to a novel synthesis of functions, which are coordinated for reading and then automatized as a package. Developmental dyslexia is explained as a Functional Coordination Deficit (Lachmann 2002), since the coordination stage is assumed to be most liable to manifest deficiencies. Developmental dyslexia is not seen as a consequence of a deficit in a single function or in automatization, but as result of automatizing a suboptimal functional coordination. This integrative approach is a mere framework, rather than an explanatory theory, and is open to multi-causal explanations. Rather than solving the puzzle, the framework offers a structure for integrating various theories on reading and dyslexia.
Loss of excitatory amino acid transporters (EAATs) has been implicated in a number of human diseases including spinocerebellar ataxias, Alzhiemer's disease and motor neuron disease. EAAT4 and GLAST/EAAT1 are the two predominant EAATs responsible for maintaining low extracellular glutamate levels and preventing neurotoxicity in the cerebellum, the brain region essential for motor control. Here using genetically modified mice we identify new critical roles for EAAT4 and GLAST/EAAT1 as modulators of Purkinje cell (PC) spontaneous firing patterns. We show high EAAT4 levels, by limiting mGluR1 signalling, are essential in constraining inherently heterogeneous firing of zebrin-positive PCs. Moreover mGluR1 antagonists were found to restore regular spontaneous PC activity and motor behaviour in EAAT4 knockout mice. In contrast, GLAST/EAAT1 expression is required to sustain normal spontaneous simple spike activity in low EAAT4 expressing (zebrin-negative) PCs by restricting NMDA receptor activation. Blockade of NMDA receptor activity restores spontaneous activity in zebrin-negative PCs of GLAST knockout mice and furthermore alleviates motor deficits. In addition both transporters have differential effects on PC survival, with zebrin-negative PCs more vulnerable to loss of GLAST/EAAT1 and zebrin-positive PCs more vulnerable to loss of EAAT4. These findings reveal that glutamate transporter dysfunction through elevated extracellular glutamate and the aberrant activation of extrasynaptic receptors can disrupt cerebellar output by altering spontaneous PC firing. This expands our understanding of disease mechanisms in cerebellar ataxias and establishes EAATs as targets for restoring homeostasis in a variety of neurological diseases where altered cerebellar output is now thought to play a key role in pathogenesis.
Two groups of male university students who had been diagnosed as dyslexic when younger, and two groups of control subjects of similar age and IQ to the dyslexics, were scanned whilst reading aloud and during a task where reading was implicit. The dyslexics performed less well than their peers on a range of literacy tasks and were strikingly impaired on phonological tasks. In the reading aloud experiment, simple words and pseudowords were presented at a slow pace so that reading accuracy was equal for dyslexics and controls. Relative to rest, both normal and dyslexic groups activated the same peri- and extra-sylvian regions of the left hemisphere that are known to be involved in reading. However, the dyslexic readers showed less activation than controls in the left posterior inferior temporal cortex [Brodmann area (BA) 37, or Wernicke's Wortschatz], left cerebellum, left thalamus and medial extrastriate cortex. In the implicit reading experiment, word and pseudoword processing was contrasted to visually matched false fonts while subjects performed a feature detection paradigm. The dyslexic readers showed reduced activation in BA 37 relative to normals suggesting that this group difference, seen in both experiments, resides in highly automated aspects of the reading process. Since BA 37 has been implicated previously in modality-independent naming, the reduced activation may indicate a specific impairment in lexical retrieval. Interestingly, during the reading aloud experiment only, there was increased activation for the dyslexics relative to the controls in a pre-motor region of Broca's area (BA 6/44). We attribute this result to the enforced use of an effortful compensatory strategy involving sublexical assembly of articulatory routines. The results confirm previous findings that dyslexic readers process written stimuli atypically, based on abnormal functioning of the left hemisphere reading system. More specifically, we localize this deficit to the neural system underlying lexical retrieval.
Beyond modularity attempts a synthesis of Fodor's anticonstructivist nativism and Piaget's antinativist constructivism. Contra Fodor, I argue that: (1) the study of cognitive development is essential to cognitive science, (2) the module/central processing dichotomy is too rigid, and (3) the mind does not begin with prespecified modules; rather, development involves a gradual process of "modularization." Contra Piaget, I argue that: (1) development rarely involves stagelike domain-general change and (2) domain- specific predispositions give development a small but significant kickstart by focusing the infant's attention on proprietary inputs. Development does not stop at efficient learning. A fundamental aspect of human development ("representational redescription") is the hypothesized process by which information that is in a cognitive system becomes progressively explicit knowledge to that system. Development thus involves two complementary processes of progressive modularization and progressive "explicitation." Empirical findings on the child as linguist, physicist, mathematician, psychologist, and notator are discussed in support of the theoretical framework. Each chapter concentrates first on the initial state of the infant mind/brain and on subsequent domain-specific learning in infancy and early childhood. It then goes on to explore data on older children's problem solving and theory building, with particular focus on evolving cognitive flexibility. Emphasis is placed throughout on the status of representations underlying different capacities and on the multiple levels at which knowledge is stored and accessible. Finally, consideration is given to the need for more formal developmental models, and a comparison is made between representational redescription and connectionist simulations of development. In conclusion, I consider what is special about human cognition by speculating on the status of representations underlying the structure of behavior in other species.
The authors propose an alternative conceptualization of the developmental dyslexias, the
double-deficit hypothesis (i.e., phonological deficits and processes underlying naming-speed deficits represent 2 separable sources of reading dysfunction). Data from cross-sectional, longitudinal, and cross-linguistic studies are reviewed supporting the presence of 2 single-deficit subtypes with more limited reading impairments and 1 double-deficit subtype with more pervasive and severe impairments. Naming-speed and phonological-awareness variables contribute uniquely to different aspects of reading according to this conception, with a model of visual letter naming illustrating both the multicomponential nature of naming speed and why naming speed should not be subsumed under phonological processes. Two hypotheses concerning relationships between naming-speed processes and reading are considered. The implications of processing speed as a second core deficit in dyslexia are described for diagnosis and intervention. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
The present study assessed reading difficulties and cognitive impairments of German-speaking dyslexic children at grade levels 2, 3, and 4. It was found that German dyslexic children suffered from a pervasive speed deficit for all types of reading tasks, including text, high frequency words, and pseudowords, but at the same time showed generally rather high reading accuracy. For pseudowords, reading refusals or word responses were absent, and the majority of errors was close to the target pronunciation. Reading speed seemed to be most impaired for pseudowords and function words that did not allow the children to take a short-cut from phonemically mediated word processing. The discussion offers a developmental framework for the interpretation of these reading difficulties. For the cognitive tasks, dyslexic children did not differ from age-matched control children on the pseudoword repetition task or the digit span task, indicating that auditory perception and memory were not impaired. On phonological awareness tasks (rhyme oddity detection, vowel substitution, and pseudoword spelling), dyslexic children scored lower than age-matched control children, but not lower than younger reading-level control children. The performance of the dyslexic children on the phonemic segmentation tasks (pseudoword spelling and vowel substitution) was high in absolute terms. In contrast, marked differences between dyslexic and age-matched controls were found on rapid naming tasks: dyslexic grade 4 children showed lower numeral-naming speed than reading-level grade 2 children. Numeral-naming speed turned out to be the most important predictor of reading speed differences. These findings are discussed in relation to the phonological impairment explanation of dyslexia and to recent alternative explanations that posit an underlying impairment in automatizing skills which demand the fast execution of low-level cognitive processes.
In this chapter we outline a sensory-linguistic approach to the study of reading skill development. We call this a sensory-linguistic approach because the focus of interest
is on the relationship between basic sensory processing skills and the ability to extract efficiently the orthographic and
phonological information available in text during reading. Our review discusses how basic sensory processing deficits are
associated with developmental dyslexia, and how these impairments may degrade word-decoding skills. We then review studies
that demonstrate a more direct relationship between sensitivity to particular types of auditory and visual stimuli and the
normal development of literacy skills. Specifically, we suggest that the phonological and orthographic skills engaged while
reading are constrained by the ability to detect and discriminate dynamic stimuli in the auditory and visual systems respectively.
Important differences have emerged between introspective measures of learning, such as recall and recognition, and performance measures, in which the performance of a task is facilitated by prior experience. Introspective remembering of unattended stimuli is poor. We investigated whether performance measures would also show a strong dependence on attention. Subjects performed a serial reaction time task comprised of a repeating 10-trial stimulus sequence. When this task was given under dual-task conditions, acquisition of the sequence as assessed by verbal reports and performance measures was minimal. Patients with Korsakoff's syndrome learned the sequence despite their lack of awareness of the repeating pattern. Results are discussed in terms of the attentional requirements of learning, the relation between learning and awareness, preserved learning in amnesia, and the separation of memory systems.
Surprisingly, the problems faced by many dyslexic children are by no means confined to reading and spelling. There appears to be a general impairment in the ability to perform skills automatically, an ability thought to be dependent upon the cerebellum. Specific behavioural and neuroimaging tests reviewed here indicate that dyslexia is indeed associated with cerebellar impairment in about 80% of cases. We propose that disorders of cerebellar development can in fact cause the impairments in reading and writing characteristic of dyslexia, a view consistent with the recently appreciated role of the cerebellum in language-related skills. This proposal has implications for early remedial treatment.
Developmental dyslexia is a neurodevelopmental condition which causes 5-10% of children to have unexpected difficulty learning to read. Many dyslexics have impaired development of the magnocellular component of the visual system, which is important for timing visual events and controlling eye movements. Poor control of eye movement may lead to unstable binocular fixation, and hence unsteady vision; this could explain why many dyslexics report that letters appear to move around, causing visual confusion. Previous research has suggested that such binocular confusion can be permanently alleviated by temporarily occluding one eye. The aim of the present study was therefore to assess the binocular control and reading progress of dyslexic children with initially unstable binocular control after the left eye was patched. One hundred and forty-three dyslexics were studied. They were selected from children aged 7-11 years referred to a learning disabilities clinic if they were dyslexic and had unstable binocular control. They were randomly assigned to wear yellow spectacles with or without the left lens occluded, and were followed for 9 months. Significantly more of the children who were given occlusion gained stable binocular fixation in the first 3 months (59%) compared with children given the unoccluded glasses (36%). This advantage was independent of IQ or initial reading ability. Furthermore, at all the 3-month follow-ups, children were more likely to have gained stable binocular control if they had been wearing the occluded glasses. Gaining stable binocular control significantly improved reading. The children who did so with the help of occlusion improved their reading by 9.4 months in the first 3 months, compared with 3.9 months in those who were not patched and did not gain stable fixation. Over the whole 9 months, children who received occlusion and gained stable fixation nearly doubled their rate of progress in reading compared with those who remained unstable. At all the follow-ups the reading of those given occlusion was significantly better than that of those not occluded. Thus monocular occlusion helped children with unstable binocular control to gain good binocular fixation. If they gained stability, they made significantly faster reading progress. The progress made by the children who gained stable fixation was much greater than that achieved with other remedial techniques.
The relationship between cerebellar function and reading abilities is unclear. One theory of developmental dyslexia implicates the cerebellum in this reading disorder. Neuroimaging studies in normal readers consistently show cerebellar activation in tasks that involve reading. However, neuropsychological evidence for a relationship between cerebellar function and skilled reading is sparse. To further examine the role of the cerebellum in reading, we assessed reading skills and phonological processing in a group of patients with focal damage to the cerebellum. The patients' accuracy in naming single words and nonwords and their reading fluency and comprehension did not differ from that of age- and education-matched healthy controls. The patients' performance on phonological awareness and phonological memory tasks was also within the range of the control group, although their performance was highly variable. In contrast, cerebellar damage did significantly compromise performance in two other tasks associated with phonological processing. In a visual rhyme judgment task, a subset of the patient group was impaired on items with a mismatch between orthographic and phonological information. On a verbal working memory task, the cerebellar compared to the control group recalled fewer items from a list of nonwords, but not from lists of familiar items. On the basis of the patients' pattern of behavioral impairments, we propose that cerebellar damage affects an articulatory monitoring process. Our findings indicate that intact cerebellar function is not necessary for skilled reading; however, we cannot exclude the potential contribution of the cerebellum to reading acquisition.
Developmental dyslexia is diagnosed when children fail to acquire literacy skills despite adequate education and intellectual ability. There is evidence of impaired implicit learning in dyslexia, and it is possible that poor implicit learning in dyslexic children affects their acquisition of complex skills such as reading. To assess whether children with dyslexia show evidence of poor implicit motor learning, 45 dyslexic children completed a serial reaction time task (SRTT). Age-matched controls (n= 44) and nondyslexic poor readers ("garden-variety" poor readers, n= 20) were used as comparison groups. The inclusion of the garden-variety poor-reader group allows us to address the specificity of implicit learning deficits to dyslexics, as opposed to poor readers who do not have a discrepancy between their intellectual and literacy skills. There were no significant differences between the three groups in performance accuracy. However, whereas the controls and garden-variety poor readers showed good implicit learning (measured by a significant reduction in response times from a block of random to a block of sequenced trials), the dyslexic group did not. These data suggest that implicit motor learning deficits may underlie the laborious learning seen in developmental dyslexia. Because garden-variety poor readers were as able as control children to use the sequence cues to achieve better task performance, there may be differences in how garden-variety poor readers and dyslexic children acquire knowledge. This has important implications for remediation programs that are specific to children with dyslexia and for distinguishing among varieties of poor readers.
The idea that cerebellar processing is required in a variety of cognitive functions is well accepted in the neuroscience community. Nevertheless, the definition of its role in the different cognitive domains remains rather elusive. Current data on perceptual and cognitive processing are reviewed with special emphasis on cerebellar sequencing properties. Evidences, obtained by neurophysiological and neuropsychological lesion studies, converge in highlighting comparison of temporal and spatial information for sequence detection as the key stone of cerebellar functioning across modalities. The hypothesis that sequence detection might represent the main contribution of cerebellar physiology to brain functioning is presented and the possible clinical significance in cerebellar-related diseases discussed.
An in vivo anatomic study of gray matter volume was performed in a group of familial dyslexic individuals, using an optimized method of voxel-based morphometry. Focal abnormalities in gray matter volume were observed bilaterally in the planum temporale, inferior temporal cortex, and cerebellar nuclei, suggesting that the underlying anatomic abnormalities may be responsible for defective written language acquisition in these subjects.
Despite numerous studies on the effects of lesions of the mammalian cerebellum on coordination, adaptation and learning, the precise nature of this structure's contribution to motor control remains controversial. This paper reviews the results of a series of behavioural studies with monkeys trained to make rapid, accurate sequences of responses to visual targets. The effects of discrete cerebellar lesions on the performance of these animals is discussed in the light of recent theories about how the cerebellum might be concerned with learning to anticipate certain kinds of sensory events. Additional studies are considered that advocate sensory prediction as a fundamental cerebellar function that could contribute to many of the behavioural processes with which the cerebellum has been implicated. In particular, it is demonstrated how such information could be employed in the augmentation of motor learning by the formation of expectations about the sensory feedback arising from movements and interactions with the environment. Whilst it is argued that the cerebellum may not be unique in being able to perform such functions, comparative anatomical studies suggest that it may operate with an unequalled degree of temporal precision. Such precision forms the signature of skilled motor acts.
This chapter presents the relationship between structure and function in the cerebellum and brainstem. Ablation experiments continue to be a valuable tool in contemporary studies of cerebellar function in animal models. This approach has been used to demonstrate that acquisition, retention, and performance of the conditioned learning response is critically dependent upon the cerebellum. Motor learning deficits have been produced in the rat model using the cerebellar ablation paradigm. Reversible ablation paradigms are now possible using functional inactivation techniques. Physiological studies of the deep cerebellar nuclei show that each contains at least one more or less complete body map and controls different aspects of motor movement. The dentate controls synergist muscles in visually guided movements such as pinching and reaching; the interpositus controls agonist antagonist synergy and stretch reflexes at a single joint; and the fastigial nucleus controls synergists in upright stance and locomotion. These findings are consistent with the clinical observation that cerebellar lesions impair compound movements more than simple movements.
Summary In this study, we examined the neuroanatomy of dyslexic (14 males, four females) and control (19 males, 13 females) children in grades 4‐6 from a family genetics study. The dyslexics had specific deficits in word reading relative to the population mean and verbal IQ, but did not have primary language or motor deficits. Measurements of the posterior temporal lobe, inferior frontal gyrus, cerebellum and whole brain were collected from MRI scans. The dyslexics exhibited significantly smaller right anterior lobes of the cerebellum, pars triangularis bilaterally, and brain volume. Measures of the right cerebellar anterior lobe and the left and right pars triangularis correctly classified 72% of the dyslexic subjects (94% of whom had a rapid automatic naming deficit) and 88% of the controls. The cerebellar anterior lobe and pars triangularis made significant contributions to the classification of subjects after controlling for brain volume. Correlational analyses showed that these neuroanatomical measurements were also significantly correlated with reading, spelling and language measures related to dyslexia. Age was not related to any anatomical variable. Results for the dyslexic children from the family genetics study are discussed with reference to dyslexic adults from a prior study, who were ascertained on the basis of a discrepancy between phonological coding and reading comprehension. The volume of the right anterior lobe of the cerebellum distinguished dyslexic from control participants in both studies. The cerebellum is one of the most consistent locations for structural differences between dyslexic and control participants in imaging studies. This study may be the first to show that anomalies in a cerebellar-frontal circuit are associated with rapid automatic naming and the double-deficit subtype of dyslexia.
Clinical, neuroanatomic, neurobehavioral, and functional brain-imaging studies suggest a role for the cerebellum in cognitive functions, including attention. However, the cerebellum has not been systematically studied in attention-deficit hyperactivity disorder (ADHD). We quantified the cerebellar and vermal volumes, and the midsagittal areas of three vermal regions, from MRIs of 46 right-handed boys with ADHD and 47 matched healthy controls. Vermal volume was significantly less in the boys with ADHD. This reduction involved mainly the posterior inferior lobe (lobules VIII to X) but not the posterior superior lobe (lobules VI to VII). These results remained significant even after adjustment for brain volume and IQ. A cerebello-thalamo-prefrontal circuit dysfunction may subserve the motor control, inhibition, and executive function deficits encountered in ADHD.
To explore the neural networks used for Braille reading, we measured regional cerebral blood flow with PET during tactile tasks performed both by Braille readers blinded early in life and by sighted subjects. Eight proficient Braille readers were studied during Braille reading with both right and left index fingers. Eight-character, non-contracted Braille-letter strings were used, and subjects were asked to discriminate between words and non-words. To compare the behaviour of the brain of the blind and the sighted directly, non-Braille tactile tasks were performed by six different blind subjects and 10 sighted control subjects using the right index finger. The tasks included a non-discrimination task and three discrimination tasks (angle, width and character). Irrespective of reading finger (right or left), Braille reading by the blind activated the inferior parietal lobule, primary visual cortex, superior occipital gyri, fusiform gyri, ventral premotor area, superior parietal lobule, cerebellum and primary sensorimotor area bilaterally, also the right dorsal premotor cortex, right middle occipital gyrus and right prefrontal area. During non-Braille discrimination tasks, in blind subjects, the ventral occipital regions, including the primary visual cortex and fusiform gyri bilaterally were activated while the secondary somatosensory area was deactivated. The reverse pattern was found in sighted subjects where the secondary somatosensory area was activated while the ventral occipital regions were suppressed. These findings suggest that the tactile processing pathways usually linked in the secondary somatosensory area are rerouted in blind subjects to the ventral occipital cortical regions originally reserved for visual shape discrimination.
A new concept of the organization of the cerebellum into longitudinal, corticonuclear zones has been formulated (Chambers and Sprague14) on the basis of anatomical studies of Jansen and Brodal* and on our own physiological observations.† This concept stresses the importance of localization in the efferent corticonuclear projections, rather than the distribution of afferent fibers in the cerebellar cortex, in the interpretation of the results obtained by stimulation and ablation. Three bilaterally symmetrical zones have been defined in the cat (Fig. 1): (a) Each medial zone (vermal cortex and fastigial nucleus) regulates the tone, posture, locomotion, and equilibrium of the entire body; (b) each intermediate zone (paravermal cortex and nucleus interpositus) regulates the spatially organized and skilled movements and the tone and posture associated with these movements of the ipsilateral limbs, and (c) each lateral zone (hemispherical cortex and dentate nucleus) is involved in the same skilled and spatially organized
• Recent clinical and research reports suggest that the cerebellum may contribute to the modulation of higher order behavior. This article presents a critical review of both earlier and more current clinical observations that raise this possibility, as well as a review of the salient laboratory data that appear to support this contention. It also summarizes the relevant anatomic work concerning the contributions to the cortico-pontocerebellar pathways from the higher order cerebral association areas, which have been implicated as partial anatomic substrates for this putative cerebellar role in higher function. Finally, it provides a framework for the understanding of this correlation, concludes with suggestions for future areas of investigation, and recommends that patients with cerebellar lesions be studied from a neurobehavioral point of view.
Recent evidence has suggested cerebellar anomalies in developmental dyslexia. Therefore, we investigated cerebellar morphology in subjects with documented reading disabilities. We obtained T1-weighted magnetic resonance images in the coronal and sagittal planes from 11 males with prior histories of developmental dyslexia, and nine similarly-aged male controls. Proton magnetic resonance spectra (TE = 136 ms, TR = 2.4 s) were obtained bilaterally in the cerebellum. Phonological decoding skill was measured using non-word reading. Handedness was assessed using both the Annett questionnaire of hand preference and Annett's peg moving task. Cerebellar symmetry was observed in the dyslexics but there was significant asymmetry (right grey matter > left grey matter) in controls. The interpretation of these results depended whether a motor-or questionnaire-based method was used to determine handedness. The degree of cerebellar symmetry was correlated with the severity of dyslexics' phonological decoding deficit. Those with more symmetric cerebella made more errors on a nonsense word reading measure of phonological decoding ability. Left cerebellar metabolite ratios were shown to correlate significantly with the degree of cerebellar asymmetry (P < 0.05) in controls. This relationship was absent in developmental dyslexics. Cerebellar morphology reflects the higher degree of symmetry found previously in the temporal and parietal cortex of dyslexics. The relationship of cerebellar asymmetry to phonological decoding ability and handedness, together with our previous finding of altered metabolite ratios in the cerebellum of dyslexics, lead us to suggest that there are alterations in the neurological organisation of the cerebellum which relate to phonological decoding skills, in addition to motor skills and handedness.
Tested the hypothesis that the experiences that a child has with rhyme before he/she goes to school might have an effect on later success in learning to read and write. Two experimental situations were used: a longitudinal study and an intensive training program in sound categorization or other forms of categorization. 368 children's skills at sound categorization were measured before they started to read and then related to their progress in reading, spelling, and mathematics over 4 yrs. At the end of initial testing and during the 4 yrs Ss' IQ, reading, spelling, and mathematical abilities were tested. There were high correlations between initial sound categorization scores and Ss' reading and spelling over 3 yrs. At the onset of study, 65 Ss who could not read and had low sound-categorization skills were divided into 4 groups. Two received 2 yrs of training in categorizing sounds. Group 1 was taught that the same word shared common beginning, middle, and end sounds with other words and could be categorized in different ways. Group 2 was also taught how each common sound was represented by a letter of the alphabet. The other groups served as controls. Group 3 was taught only that the same word could be classified in several ways. At the end of training, Group 1 was ahead of Group 3 and Group 2 was ahead of Group 1 in reading and spelling. This suggests that training in sound categorization is more effective when it also involves an explicit connection with the alphabet. Results support the hypothesis. (5 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
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2001-11127-002) by R. I. Nicolson, A. J. Fawcett and P. Dean, who proposed that disorders of cerebellar development cause the impairments in reading and writing characteristic of dyslexia. The current authors suggest that the ideas in this hypothesis resonate with the central premise of the motor theory of speech perception. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Auditory and visual rhyme judgement tasks were administered to 16 adolescent dyslexics (age range 13–18 years, mean age 15½) and 16 age-matched normal readers. Dyslexics and controls demonstrated orthographic facilitation in both tasks, i.e. rhymes with matching orthography, e.g. king, sing, were responded to faster than rhymes with dissimilar orthography, e.g. chair, dare, thus indicating short term memory storage of orthographic information during visual presentations, as well as activation of orthographic information during auditory presentations. Despite this facilitation dyslexics made significantly more errors and responded significantly slower than controls in both tasks. Dyslexics had extremely high error rates for visual rhyme judgement trials in which phonological and orthographic information were inconsistent, i.e. rhymes that had different orthographic endings, e.g. chair, dare, and non-rhymes that had similar orthographic patterns, e.g. food, blood. The dyslexics' high error rates and slow reaction times are discussed in terms of poor phonological processing, lack or orthographic flexibility and slow processing speeds. © 1997 John Wiley & Sons, Ltd.
The projections to the basis pontis from cytoarchitectonically defined subregions of the superior (SPL) and inferior (IPL) parietal lobules were investigated in 14 rhesus monkeys by using the anterograde tracing techniques of autoradiography and horseradish peroxidase histochemistry. The results of our study confirm and complement available information regarding the parietopontine projections. The projections are found in clusters distributed in lamellae approximately concentric to the peduncle. They are directed most heavily towards the peripeduncular and lateral nuclei of the pons. There are also lesser, but nevertheless substantial projections to other nuclei including the intrapeduncular, ventral, dorsolateral, extreme dorsolateral, and dorsal nuclei. The dorsomedial, paramedian, and NRTP nuclei receive only minor projections. The SPL projections are relatively widespread with respect to the more focussed IPL projections. The IPL projections are, in general, situated more laterally and at more rostral levels of the pontine nuclei than are those of the SPL.
Functional magnetic resonance imaging was used to identify the neural correlates of Chinese character and word reading. The Chinese stimuli were presented visually, one at a time. Subjects covertly generated a word that was semantically related to each stimulus. Three sorts of Chinese items were used: single characters having precise meanings, single characters having vague meanings, and two-character Chinese words. The results indicated that reading Chinese is characterized by extensive activity of the neural systems, with strong left lateralization of frontal (BAs 9 and 47) and temporal (BA 37) cortices and right lateralization of visual systems (BAs 17–19), parietal lobe (BA 3), and cerebellum. The location of peak activation in the left frontal regions coincided nearly completely both for vague- and precise-meaning characters as well as for two-character words, without dissociation in laterality patterns. In addition, left frontal activations were modulated by the ease of semantic retrieval. The present results constitute a challenge to the deeply ingrained belief that activations in reading single characters are right lateralized, whereas activations in reading two-character words are left lateralized. Hum. Brain Mapping 10:16–27, 2000. © 2000 Wiley-Liss, Inc.
This paper reviews a body of prominent theoriesof automaticity in developmental dyslexia. Thefirst part of the review considers therelationship between dyslexia and rapidautomatic naming and fluency. Additionaltheoretical and empirical advances aresuggested to this already strong research base.In particular, there is a need is forexperimental work elucidating the nature ofnaming speed deficits and providing independentevidence of the automaticity of rapid naming.The second part of the review considersevidence for deficits in motor automaticity indyslexic children. Here, a more mixed patternof results is evident. It is concluded thatthere is currently clearer evidence forlanguage-based than motor-based automaticitydeficits. Future motor automaticity research islikely to require the routine screening of poorreaders for common co-occurring developmentaldifficulties, improved sampling and prospectivelongitudinal studies.
This article examines the characteristics of surface dyslexia in a language (Italian) with high grapheme-phoneme correspondence. The reading performances of four boys are reported. The most pervasive reading symptom was severe slowness, which was associated in some, but not all, cases with reduced text comprehension. All four dyslexics performed at chance level on a task requiring comprehension of homophonous words (Study I). Vocal reaction times to single words were delayed with respect to the controls and showed a clear word length effect (Study II). However, vocal reaction times to pictorial stimuli were normal (Study III). Eye movement recordings taken during reading indicated an increased number and a reduced amplitude of rightward saccades and longer fixation durations (Study IV). A test of letter recognition in central and peripheral vision indicated that the reading deficit could not be explained in terms of an abnormal attentional "window," as found in other cases of dyslexia (Study V). An analysis of the boys' cognitive skills (Study VI) indicated spared phonological awareness in three of four subjects; a severe deficit in rapid scanning of nonlinguistic stimuli was present in all of the subjects. Overall, these results indicate that parallel visual processing of words was impaired, and that the boys analyzed words sequentially, presumably through an orthographic-phonological conversion. This condition may be interpreted as surface dyslexia, even though the prominent characteristics of this syndrome are somewhat different in Italian than in other languages. In languages with "loose" relationships between graphemes and phonemes (e.g., English), when the phonological analysis of words is insufficient, a variety of errors is produced. In languages with considerably more regular grapheme-phoneme correspondence (e.g., Italian), the number of errors may be small since phonological reading is generally correct, and the most conspicuous symptom is slowness in reading.
The central assumption of existing models of motor learning in the cerebellum is that cerebellar mossy fibres signal information about the context in which a movement is to be performed and climbing fibres signal in relation to a movement error. This leads to changes in the responsiveness of Purkinje cells, which on the next occasion will generate a corrected output in a given context. Support for this view has come mainly from work on adaptation of the vestibulo–ocular reflex. The discovery that classically conditioned eyeblink responses depend critically on the cerebellum offers the possibility to study the learning of a novel behaviour, rather than modification of an existing reflex. After repeated pairing of a neutral stimulus, such as a tone, with a blink-eliciting stimulus, the tone will acquire the ability to elicit a blink on its own. We review evidence from studies employing a wide variety of techniques that the cerebellum is critical in this type of learning as well as evidence that mossy and climbing fibres have roles assigned to them in cerebellar learning models.
Clinical, experimental and neuroimaging studies indicate that the cerebellum is involved in neural processes beyond the motor domain. Cerebellar somatotopy has been shown for motor control, but topographic organization of higher-order functions has not yet been established. To determine whether existing literature supports the hypothesis of functional topography in the human cerebellum, we conducted an activation likelihood estimate (ALE) meta-analysis of neuroimaging studies reporting cerebellar activation in selected task categories: motor (n = 7 studies), somatosensory (n = 2), language (n = 11), verbal working memory (n = 8), spatial (n = 8), executive function (n = 8) and emotional processing (n = 9). In agreement with previous investigations, sensorimotor tasks activated anterior lobe (lobule V) and adjacent lobule VI, with additional foci in lobule VIII. Motor activation was in VIIIA/B; somatosensory activation was confined to VIIIB. The posterior lobe was involved in higher-level tasks. ALE peaks were identified in lobule VI and Crus I for language and verbal working memory; lobule VI for spatial tasks; lobules VI, Crus I and VIIB for executive functions; and lobules VI, Crus I and medial VII for emotional processing. Language was heavily right-lateralized and spatial peaks left-lateralized, reflecting crossed cerebro-cerebellar projections. Language and executive tasks activated regions of Crus I and lobule VII proposed to be involved in prefrontal-cerebellar loops. Emotional processing involved vermal lobule VII, implicated in cerebellar-limbic circuitry. These data provide support for an anterior sensorimotor vs. posterior cognitive/emotional dichotomy in the human cerebellum. Prospective studies of multiple domains within single individuals are necessary to better elucidate neurobehavioral structure–function correlations in the cerebellar posterior lobe.
This introduction describes some of the general concepts regarding the structure and functions of the cerebellum to give an insight into the more specific topics dealt with in this Special Issue on Language and Cerebellum. A short excursus on early discoveries of cerebellar functions is followed by a schematic description of the cerebellar cortex, the deep cerebellar nuclei, efferent fibers from, and afferent fibers to the cerebellum, and the cerebellar circuitry. The main neurological symptoms following cerebellar lesions are reported. In the final part, the possible role played by the cerebellum in the regulation of linguistic, cognitive and emotional processes is discussed (learning and procedural memory, visuo-spatial tasks, attention and sensorimotor tasks, language and verbal memory, learning disabilities, and vegetative and emotional functions).