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Temporal information processing in the nervous system: Special reference to dyslexia and dysphasia. Annals of the New York Academy of Sciences, Vol. 682.

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Abstract

Traditionally, developmental disorders of language (dysphasia) and reading (dyslexia) have been viewed as distinct clinical syndromes. But, more recent research findings have suggested a close link between these developmental learning disabilities. Temporal mechanisms in the nervous system play a central role in fundamental aspects of information processing and production, and may be especially critical for the normal development and maintenance of sensory motor integration systems as well as phonological systems. The goal of this [book] was to integrate research findings pertaining to temporal information processing in the nervous system from divergent areas by bringing together scientists whose research focuses on the neural mechanisms underlying temporal integration, mechanisms underlying phonological processes, and studies with language- and reading-impaired children. It is hoped that [this book] will serve to integrate the relevant anatomical, physiological, and behavioral data pertaining to temporal information processing in the nervous system, with special reference to temporal dysfunctions in children with developmental language and reading disorders. (PsycINFO Database Record (c) 2012 APA, all rights reserved)

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... Over time, the availability of new techniques, theory and advances in research may lead to increased acceptability of a new or less favored perspective within the wider scientific community (Rappa & Debackere, 1995). Theoretical advances may provide a means of reconciling disparate results and views within an integrative framework (e.g., see Rayner, 1993; Stanovich, 1993; Tallal, Galaburda, Llinas, & von Euler, 1993). Whitley (1984) notes that Kuhn's unitary model of knowledge development does not take into account how different sorts of knowledge are produced in different social contexts (p. ...
... The debate was undoubtedly exacerbated by rivalries between two professions concerned with the delivery of eye care— optometry and ophthalmology— influenced by differences in treatment advocacy (American Academy of Ophthalmology, 1987; Flax, Mozlin, & Solan, 1984); legislative efforts have enlarged the scope of optometric practice to include the diagnostic and therapeutic use of drugs, and an overabundance of ophthalmologists (Nore­ ika, 1990). In recent years, however, there has been renewed inter­ est in the visual perceptual component to reading disabil­ ity (e.g., Eden, Stein, Wood, & Wood, 1995; Kruk, 1991; Lehmkuhle, Garzia, Turner, Hash, & Baro, 1993) follow­ ing advances in the neurobiological, genetic, cognitive and neuropsychological aspects of dyslexia (Galaburda, 1993), and the proposal that underlying deficits in tempo­ ral processing may account for both phonological (lin­ guistic) as well as visual and auditory perceptual prob­ lems in developmental disabilities (Tallal et al., 1993). It is likely that these efforts were spurred in large part by a major increase in federal funding of research into the biological basis of learning disabilities. ...
... of Bakker, Benton, Galaburda, and Tallal, whose published work is closely identified with a neuroscientific focus (e.g., H1b. In the Co-Citation Network Structure, PhonologBakker, Moerland, & Goekoop-Hoetkens, 1981; Benton, ical Dyslexia Researchers Are More Highly Co-Cited with 1975; Galaburda, 1989; Tallal et al., 1993). All of these ...
Article
Based on Mulkay's and Kuhn's models of change in sci­ entific structure, a scientific communication model of the emergence of a hybrid research area was developed and tested in the field of developmental dyslexia. Data included co-citation data on 74 dyslexia researchers at three points in time, who-to-whom communication net­ work data, survey responses, resumes, association and biographical sources, online reference and citation data- bases, publications, grant databases, and telephone in­ terviews. Researchers were partitioned into ''blocks'' of similar scientists on the basis of co-citation and commu­ nication relations, compared on selected network-level and individual-level characteristics in order to validate block labels, and situated historically in the politics and advances surrounding the problem area. Results show support for Mulkay's model of branching instead of Kuhn's model of scientific revolution. Evidence points to divergence rather than convergence among the related research areas, but suggests the need for longitudinal follow-up in order to rule out the impact of the inertia of aggregate co-citation data. Implications for theory, methodology, and research are discussed.
... Dyslexia correlates with impaired processing of rapid sequences of linguistic and non-linguistic information. This is consistently observed in dyslexic children and adults with physiological[9][10][11][12]and psychophysical methods[12][13][14][15][16]across modalities. Most dyslexic readers learn to read by compensating the original difficulty by harder than normal practice. ...
... Accordingly, it could show accelerated age-related deterioration. Temporal impairment of dyslexia may be based on an anatomical defect of magnocells in several brain systems[9][10][11][12][13][14][15][16]. The cells in magnocellular areas are abnormally small, and the brains of dyslexics contain cortical ectopias, dysplasias, and glial scars[9,17,18]. ...
Article
Several studies show that although function may recover after brain damage the insult can nevertheless cause accelerated deterioration in old age. This has been interpreted as indicating reduced neuronal capacity to counteract age-related decline with plastic changes. Psychosocial and compensatory factors obscure the neuronal explanation. Since the speed of processing sequential temporal information is impaired in developmental dyslexia, we investigated its dependence on age (20-59 years) in psychosocially comparable groups of dyslexic and fluent readers using six tasks. Processing speed was impaired in dyslexia and decreased with age. The decrement was faster in dyslexic than normal readers in processing periodic stimuli. No exacerbation occurred in reading and other experiential factors. Our results, therefore, support the neuronal explanation.
... Overall group differences were tested with multivariate analyses of variance (MANOVA) and mixed analyses of variance (ANOVA). Since we hypothesized a priori that the dyslexic readers would perform more poorly than their controls (Farmer & Klein, 1995; Tallal, Galaburda, et al., 1993; Tallal et al., 1998), group differences in individual tasks were analyzed with one-tailed t tests (corrected for unequal variances when required). Two-tailed t-test p values are reported in all other cases. ...
... The developmentally dyslexic readers may of course include sub-populations only some of which experience difficulties in visual temporal processing (Borsting et al., 1996; Ridder, Borsting, Cooper, McNeel, & Huang, 1997; Slaghuis & Ryan, 1999). The differences between the poor readers and the normal readers in our tactile millisecond-level measures of temporal acuity support suggestions that difficulties in dyslexia are not limited to linguistic difficulties or to impairments in perceptual systems most directly involved in speech processing (audition) and reading (vision) (Stein & Walsh, 1997; Summerfield & Michie, 1993; Tallal, Galaburda, et al., 1993; Tallal et al., 1985 ). Also, functions such as postural stability or muscle tone (e.g., Fawcett & Nicolson, 1999) and motor output (e.g., Moore, Brown, Markee, Theberge, & Zvi, 1995; Wolff, Michel, Ovrut, & Drake, 1990) appear to be affected in dyslexia. Several earlier studies have also indicated the pansensory nature of temporal acuity impairment of sequences in SLI (Tallal & Piercy, 1973b; Tallal et al., 1981) and dyslexia (Kinsbourne et al., 1991; Laasonen et al., 2000). ...
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We studied the temporal acuity of 16 developmentally dyslexic young adults in three perceptual modalities. The control group consisted of 16 age- and IQ-matched normal readers. Two methods were used. In the temporal order judgment (TOJ) method, the stimuli were spatially separate fingertip indentations in the tactile system, tone bursts of different pitches in audition, and light flashes in vision. Participants indicated which one of two stimuli appeared first. To test temporal processing acuity (TPA), the same 8-msec nonspeech stimuli were presented as two parallel sequences of three stimulus pulses. Participants indicated, without order judgments, whether the pulses of the two sequences were simultaneous or nonsimultaneous. The dyslexic readers were somewhat inferior to the normal readers in all six temporal acuity tasks on average. Thus, our results agreed with the existence of a pansensory temporal processing deficit associated with dyslexia in a language with shallow orthography (Finnish) and in well-educated adults. The dyslexic and normal readers' temporal acuities overlapped so much, however, that acuity deficits alone would not allow dyslexia diagnoses. It was irrelevant whether or not the acuity task required order judgments. The groups did not differ in the nontemporal aspects of our experiments. Correlations between temporal acuity and reading-related tasks suggested that temporal acuity is associated with phonological awareness.
... The third factor in the present study with Dutch children was characterized as verbal-sequential processing problems. Verbal-sequential processing deficits are often found to be present in children with SLI (Cowan, 1996;Ellis Weismer et al., 1999;Montgomery, 2000;Tallal, Galaburda, Llinas, & Von Euler, 1993) and they cannot be attributed to the language problem itself (Cowan, 1996). The final factor speech production represents expressive problems in Dutch children with SLI. ...
... This factor comprised tasks requiring sequential processing at the level of syntax (e.g., Sentence Reproduction), words (e.g., Number Recall and Word Order), and phonemes (e.g., Phonological Contrasts). It is reported that some children with SLI have a core deficit in processing sequential information (Cowan, 1996;Ellis Weismer et al., 1999;Montgomery, 2000;Tallal et al., 1993) and Nickisch and von Kries (2009) argued that language abilities, long-term memory, and short-term memory influence one another. Rapid Naming is also one of the tests underlying this factor. ...
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Unlabelled: This longitudinal investigation on Dutch children with Specific Language Impairment (SLI) aimed at determining the predictive value of statistically uncorrelated language proficiencies on later reading and spelling skills in Dutch. Language abilities, tested with an extensive test battery at the onset of formal reading instruction, were represented by four statistically uncorrelated factors: lexical-semantic abilities, auditory perception, verbal-sequential processing, and speech production. All factors contributed significantly to the prediction of word reading and spelling development seven months later. Verbal-sequential processing was the strongest predictor for both word decoding and spelling. Furthermore, autoregression effects of word decoding and spelling were strong and verbal-sequential processing had predictive value on word spelling nineteen months later when pre-existing spelling abilities were accounted for. Children with SLI and normal literacy skills performed better on most of the language and language-related measures than children with SLI and poor literacy skills. Learning outcomes: As a result of this activity, readers will describe four language domains that are related to later literacy skills in children with Specific Language Impairment (SLI). As a result of this activity, readers will recognize the predictive value of each of these language domains and the important role of verbal-sequential processing in learning to decode and writing words for children with SLI. As a result of this activity, readers will recall the differences in language proficiencies between children with SLI who develop normal literacy skills and those who encounter literacy problems.
... A brain that does not distinguish quickly enough does not have the ability to distinguish between language sounds, which is a prerequisite for a child to learn to read. Hence, deviations in one or more of these processing skills can cause reading to degrade [31,32]. Additionally, deviations in the transient visual system, which reveals movements and changes in figures, is considered important for transmitting what one sees peripherally when reading [33]. ...
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Introduction. The focus of the present paper is on (1) how dyslexia research and hence definitions have developed during the period 1950–2020 and includes (2) a database search of scientific publications on dyslexia during the same period. The focus is on the definitions of dyslexia and the organization of the network search based on the causal four-level model by Morton and Frith. Method. (1) The definitions are presented in accordance with a historic review of dyslexia research from 1950 to 2020 and based on (2) Google Scholar counts of publications on dyslexia, on defining dyslexia, on dyslexia at the four levels (symptomatic, cognitive, biological, environmental), and by areas (sensorimotor, comorbidity). Finally, a percentage calculation shows the relative development within each level and area by decennium (1950–1960, 1960–1970, 1970–1980, 1990–2000, 2002–2010, 2010–2020). Results. (1) Of the seven definitions presented, only the definition by the BDA 2007 included the four levels of the causal model. (2) The number of publications increased substantially over the period. However, relatively few publications have defined dyslexia. An increase in publications from 1950 to 2020 was seen across the four levels and two areas—however, with an alteration in the thematic focus over this time span. Summary. Defining dyslexia has still not reached a consensus. This uncertainty may explain why only one of the seven definitions proved satisfactory according to the four-level model. Along with the general increase in research, publications on dyslexia have increased accordingly during the period 1950 to 2020. Although the symptomatic level has played a dominant role over the whole period, thematic shifts have been seen over these 70 years. In particular, a substantial thematic shift was seen by the turn of the millennium. There has been a relative increase in the focus on literacy at the symptomatic level, on phonological awareness at the cognitive level, in gender at the biological level, and second language learning as comorbidities. However, increases in counts are not alone a valid indication of scientific progress. In particular, the lack of definitional criteria as a basis for participant and method selection should attract much more focus in future studies. The present study underlines the multifactorial nature of dyslexia, as evidenced by a substantial increase in the number of publications on the subject. It is a challenge for future research to continuously use and possibly redefine dyslexia definitions in line with such standards.
... Neville, Coffey, Holcomb, and Tallal (1993) recorded auditory-evoked responses (AERs) to a standard tone of 1,000 Hz and to a target tone of 2,000 Hz, with different interstimulus intervals in a group of normal children and a group of children with LI. They observed significant differences between groups only when the children with LI were split into two subgroups based on their behavioral performance on the rapid sequencing subtest of the Tallal Repetition Test. ...
Chapter
In recent years important advances have been made in the analysis of processes that are affected in different groups of children with cognitive deficits. For example, developmental disorders of language (dysphasia) and reading (dyslexia) had been viewed as distinct clinical syndromes, although more recent research findings have suggested a clear link between these developmental learning disabilities. First, longitudinal studies have demonstrated that children with language disorders are at very high risk for developing reading disabilities. Second, neuropsychological profiles specifically focused on the areas of phonological disorders and specific temporal processing deficits appear to be quite similar for children with developmental language and reading disorders (Tallal, Galaburda, Llinas, and von Euler, 1993).
... Following this line of research, Wolff and colleagues (Wolff, Cohen, & Drake, 1984; Wolff, 2002) have, in a series of studies, investigated the impact of timing deficits through the use of motorically based measures of functioning. The utility of using motor based measures to investigate cognitive processes has been a major tool for understanding multiple disorders, such as Parkinson's disease and Schizophrenia, in both adults and children (Llinas, 1993). One advantage of using motor based measures is the accessibility by which complex motor patterns can be decomposed into component processes without overly altering the primary behavior (Wolff, 1999). ...
Article
Multiple domains of deficit have been proposed to account for the apparent reading failure of children with a reading disability. Deficits in both phonological awareness and rapid automatized naming are consistently linked with the development of a reading disability in young school age children. Less research, however, has sought to connect these two reading related processes to global theories of deficit, such as temporal processing deficits, in the explanation of reading fluency difficulties. This study sought to explore the relationship between aspects of temporal processing, as indexed through measures of motor fluency and control, and measures of reading related processes, phonological awareness and rapid automatized naming, to word reading fluency. Using structural equation modeling, measures of patterned motor movement were found to be negatively and significantly related to measures of phonological awareness. Measures of oral and repetitive movement were found to be positively and significantly related to measures of patterned movement. Finally, phonological awareness was found to be a significant predictor of word reading fluency both independently and through rapid automatized naming. No direct relationship between measures of motor control and fluency and
... We feel no disparity in our sense of consciousness in such circumstances since we have come to learn that this particular desyncronization of environmental events is, in these circumstances 'normal.' However, if all experience were so represented and the inter-sensory disparity between more than one sensory system was a frequent occurence, one can immediately envisage the mental mayhem it would potentially wreak, and indeed such forms of temporal, sensory desynchronization have been thought to lie behind some forms of mental illness, (see Mundell, Mayes, MacDonald, Pickering, & Fairbairn, 1991;Tallal, Galaburda, Llinas, & von Euler, 1993). ...
Article
This paper addresses the persistent problem concerning the integration of physical (external) with psychological (internal) expressions of time. While the history of cosmological science demonstrates the fallacy of the conception of the physically privileged observational point in the Universe, I argue that it is just such a privileged position which characterizes the unitary nature of individual human consciousness. A rational, but flawed implication of this latter observation is that there is a unique spatiotemporal point within the brain at which reality is experienced. This flaw can be exposed through reference to the sensory simultaneity problem. Evidence indicates that since no such unique neural location exists, the brain finesses the issue of absolute timing at a sensory level by simply avoiding the problem of time-tagging such events altogether. While this finesse solves the simultaneity conundrum at a sensory level, I argue that the need for personal temporal continuity and the ability to outpace exogenous time by the projection of possible futures are solved elsewhere in the brain. A brief account of these latter properties is also presented.
... As intervals between tone pairs are shortened, dysphasics are significantly more adversely affected than controls. Tallal, in a series of papers, demonstrated89101112 that language impaired children have problems processing auditory information when presented at a normal rate. This deficit reflects their inability to process the rapid acoustic changes that lie within normal speech streams. ...
Article
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Background Language comprehension requires decoding of complex, rapidly changing speech streams. Detecting changes of frequency modulation (FM) within speech is hypothesized as essential for accurate phoneme detection, and thus, for spoken word comprehension. Despite past demonstration of FM auditory evoked response (FMAER) utility in language disorder investigations, it is seldom utilized clinically. This report's purpose is to facilitate clinical use by explaining analytic pitfalls, demonstrating sites of cortical origin, and illustrating potential utility. Results FMAERs collected from children with language disorders, including Developmental Dysphasia, Landau-Kleffner syndrome (LKS), and autism spectrum disorder (ASD) and also normal controls - utilizing multi-channel reference-free recordings assisted by discrete source analysis - provided demonstratrions of cortical origin and examples of clinical utility. Recordings from inpatient epileptics with indwelling cortical electrodes provided direct assessment of FMAER origin. The FMAER is shown to normally arise from bilateral posterior superior temporal gyri and immediate temporal lobe surround. Childhood language disorders associated with prominent receptive deficits demonstrate absent left or bilateral FMAER temporal lobe responses. When receptive language is spared, the FMAER may remain present bilaterally. Analyses based upon mastoid or ear reference electrodes are shown to result in erroneous conclusions. Serial FMAER studies may dynamically track status of underlying language processing in LKS. FMAERs in ASD with language impairment may be normal or abnormal. Cortical FMAERs can locate language cortex when conventional cortical stimulation does not. Conclusion The FMAER measures the processing by the superior temporal gyri and adjacent cortex of rapid frequency modulation within an auditory stream. Clinical disorders associated with receptive deficits are shown to demonstrate absent left or bilateral responses. Serial FMAERs may be useful for tracking language change in LKS. Cortical FMAERs may augment invasive cortical language testing in epilepsy surgical patients. The FMAER may be normal in ASD and other language disorders when pathology spares the superior temporal gyrus and surround but presumably involves other brain regions. Ear/mastoid reference electrodes should be avoided and multichannel, reference free recordings utilized. Source analysis may assist in better understanding of complex FMAER findings.
... The generalized magnocellular hypothesis does not claim that perception is not impaired in other modalities. Rather, de®cient magnocellular processing is considered the visual aspect of a general, pan-sensory impairment in the ability to process brief and rapidly emitted stimuli (Tallal et al., 1993; Witton et al., 1998; Stein and Talcott, 1999). Thus, failure in tasks that utilize relatively long stimuli and do not require detection or discrimination of brie¯y presented cues would challenge the magnocellular hypothesis. ...
Article
Full-text available
The magnocellular theory is a prominent, albeit controversial view asserting that many reading disabled (RD) individuals suffer from a specific impairment within the visual magnocellular pathway. In order to assess the validity of this theory we tested its two basic predictions. The first is that a subpopulation of RD subjects will show impaired performance across a broad range of psychophysical tasks relying on magnocellular functions. The second is that this subpopulation will not be consistently impaired across tasks that do not rely on magnocellular functions. We defined a behavioural criterion for magnocellular function, which incorporates performance in flicker detection, detection of drifting gratings (at low spatial frequencies), speed discrimination and detection of coherent dot motion. We found that some RD subjects (six out of 30) had impaired magnocellular function. Nevertheless, these RD subjects were also consistently impaired on a broad range of other perceptual tasks. The performance of the other subgroup of RD subjects on magnocellular tasks did not differ from that of controls. However, they did show impaired performance in both visual and auditory non-magnocellular tasks requiring fine frequency discriminations. The stimuli used in these tasks were neither modulated in time nor briefly presented. We conclude that some RD subjects have generally impaired perceptual skills. Many RD subjects have more specific perceptual deficits; however, the "magnocellular" level of description did not capture the nature of the perceptual difficulties in any of the RD individuals assessed by us.
... Several studies have reported that children with SLI and dyslexia cannot differentiate between rapidly changing consonant–vowel (CV) syllables when presented at normal speed (Tallal, Miller, & Fitch, 1993; Tallal et al., 1996). It has been suggested that this ability is important for language acquisition and the development of phonological awareness and reading skills (Talcott et al., 2000; Tallal et al., 1993) and that deficits in this domain may result in impaired language facility including reading. The intervention program studied here attempts to address such deficits by modifying normal speech in such a way that the most rapidly changing components are extended in time by 50% and amplified by up to 20 dB (Nagarajan et al., 1998; Tallal et al., 1996). ...
Article
This study assessed the ability of seven children to accurately judge relative durations of auditory and visual stimuli before and after participation in a language remediation program. The goal of the intervention program is to improve the children's ability to detect and identify rapidly changing auditory stimuli, and thereby improve their language-related skills. Children showed improved accuracy on a test of auditory duration judgement following the intervention without analogous improvements in the visual domain, supporting the assertion that intensive training with modified speech improves auditory temporal discrimination. However, these improvements did not generalize to reading skills, as assessed by standard measures of phonological awareness and non-word reading.
... A variety of hypotheses can be found in the literature about the origin of SLDs. Research on dyslexia, the SLD that has been investigated for longer than others, has identified several factors that can be considered possible causes: phonological disorders (Ramus, 2003;Snowling, 2001), the lack of automation of the connection between visual perception and language (Tallal et al., Miller, & Fitch, 1993), specific visuoperceptual disorders and magnocellular system disorders (Stein, 2001Best & Demb, 1999Livingstone, Rosen, Drislane, & Galaburda, 1991;Best & Demb, 1999Stein, 2001. The traditional distinction between "core deficit" symptoms and secondary symptoms has been criticised (Nicolson & Fawcett, 2007) and, to date, wide agreement has been reached on the idea of a multifactorial origin of SLDs (Pennington, 2006Bishop, 2015Gooch, Hulme, Nash, & Snowling, 2013;Pennington, 2006;van Bergen, van der Leij, & De Jong, 2014;Bishop, 2015). ...
Article
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The aim of the present research is to investigate the prevalence of Specific Learning Disorders (SLD) in Ogliastra, an area of the island of Sardinia, Italy. Having experienced centuries of isolation, Ogliastra has become a high genetic homogeneity area, and is considered particularly interesting for studies on different kinds of pathologies. Here we are going to describe the results of a screening carried out throughout 2 consecutive years in 49 second grade classes (24 considered in the first year and 25 in the second year of the study) of the Ogliastra region. A total of 610 pupils (average age 7.54 years; 293 female, 317 male) corresponding to 68.69% of all pupils who were attending second grade in the area, took part in the study. The tool used for the screening was "RSR-DSA. Questionnaire for the detection of learning difficulties and disorders", which allowed the identification of 83 subjects at risk (13.61% of the whole sample involved in the study). These subjects took part in an enhancement training program of about 6 months. After the program, pupils underwent assessment for reading, writing and calculation abilities, as well as cognitive assessment. According to the results of the assessment, the prevalence of SLDs is 6.06%. For what concerns dyslexia, 4.75% of the total sample manifested this disorder either in isolation or in comorbidity with other disorders. According to the first national epidemiological investigation carried out in Italy, the prevalence of dyslexia is 3.1-3.2%, which is lower than the prevalence obtained in the present study. Given the genetic basis of SLDs, this result, together with the presence of several cases of SLD in isolation (17.14%) and with a 3:1 ratio of males to females diagnosed with a SLD, was to be expected in a sample coming from a high genetic homogeneity area. Copyright © 2015 Elsevier Ltd. All rights reserved.
... Right ear dominance was supposed to facilitate a more rapid processing of speech sounds [29]. The test's rationale for importance of right ear-dominance was validated by Tallal, Miller, and Holly Fitch [51] and by Okamoto, Stracke, Ross, Kakigi, and Pantev [33]. ...
Article
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The aims of the present study were to (a) compare healthy children in terms of sensorimotor maturity to untreated children diagnosed with developmental coordination disorder (DCD) and (b) compare healthy children to diagnosed children following completed treatment with sensorimotor therapy. Participants were 298 children, 196 boys and 102 girls, distributed into a Norm group of healthy children (n = 99) and a group of children diagnosed with DCD (n = 199) with a total mean age of 8.77 years (SD = 2.88). Participants in both groups were assessed on instruments aimed to detect sensorimotor deviations. The children in the DCD group completed, during on average 36 months, sensorimotor therapy which comprised stereotypical fetal- and infant movements, vestibular stimulation, tactile stimulation, auditory stimulation, complementary play exercises, gross motor milestones, and sports-related gross motor skills. At the final visit a full assessment was once more performed. Results showed that the Norm group performed better on all sensorimotor tests as compared to the untreated children from the DCD group, with the exception of an audiometric test where both groups performed at the same level. Girls performed better on tests assessing proprioceptive and balance abilities. Results also showed, after controls for natural maturing effects, that the children from the DCD group after sensorimotor therapy did catch up with the healthy children. The concept of “catching-up” is used within developmental medicine but has not earlier been documented with regard to children and youth in connection with DCD.
... and www.brainconnection.com). This sensitive application of psychological knowledge and new methods blended with high technology has resulted in enhanced quality of life for these children as well as their families and teachers, not to mention much money and resources saved (see Holly Fitch & Tallal, 2003; Tallal & Benasich, 2002; Tallal, Galaburda, Llinas, & Von Euler, 1993). ...
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The intellectual tension between the virtues of basic versus applied research that characterized an earlier era of psychology is being replaced by an appreciation of creative applications of all research essential to improving the quality of human life. Psychologists are positioned to "give psychology away" to all those who can benefit from our wisdom. Psychologists were not there 35 years ago when American Psychological Association (APA) President George Miller first encouraged us to share our knowledge with the public. The author argues that psychology is indeed making a significant difference in people's lives; this article provides a sampling of evidence demonstrating how and why psychology matters, both in pervasive ways and specific applications. Readers are referred to a newly developed APA Web site that documents current operational uses of psychological research, theory, and methodology (its creation has been the author's primary presidential initiative): www.psychologymatters.org.
... Dentro del conjunto de procesos cognitivos propuestos como responsable del espectro de conductas observado en la dislexia, nos centraremos en aquellos relacionados con los procesos psicolingüísticos, concretamente con el procesamiento fonológico al ser el déficit más sólidamente avalado por la evidencia científica actualmente disponible (Pugh y cols., 2001). Sin embrago, hay que subrayar que algunos autores han propuesto que el déficit fonológico y el trastorno lector serían secundarios a sutiles defectos perceptivos en los sistemas sensoriales visual y auditivo (Tallal, Galaburda, Llinás, von Euler, 1993), pero esta hipótesis está aún lejos de estar consolidada como alternativa o complemento de la teoría del déficit fonológico (Ramus, 2001). ...
Article
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El aprendizaje de las habilidades escolares básicas implican procesos psicológicos complejos que requieren la participación de múltiples áreas cerebrales. El presente trabajo se centra en el trastorno lector y presenta evidencias desde distintos campos psicobiológicos que sugieren una etiología neurobiológica para la dislexia evolutiva que, fundamentalmente interferiría con las habilidades relacionadas con la conciencia fonológica (hipótesis del déficit fonológico). Se presenta posteriormente un modelo neurocognitivo de lectura normal en el cual se especifican las distintas rutas para leer, y se realizan distintos comentarios para el tratamiento de la dislexia y los métodos de enseñanza de la lectura.
... The generalized magnocellular hypothesis does not claim that perception is not impaired in other modalities. Rather, de®cient magnocellular processing is considered the visual aspect of a general, pan-sensory impairment in the ability to process brief and rapidly emitted stimuli (Tallal et al., 1993;Witton et al., 1998;Stein and Talcott, 1999). Thus, failure in tasks that utilize relatively long stimuli and do not require detection or discrimination of brie¯y presented cues would challenge the magnocellular hypothesis. ...
Article
The magnocellular theory is a prominent, albeit controversial view asserting that many reading disabled (RD) individuals suffer from a specific impairment within the visual magnocellular pathway. In order to assess the validity of this theory we tested its two basic predictions. The first is that a subpopulation of RD subjects will show impaired performance across a broad range of psychophysical tasks relying on magnocellular functions. The second is that this subpopulation will not be consistently impaired across tasks that do not rely on magnocellular functions. We defined a behavioural criterion for magnocellular function, which incorporates performance in flicker detection, detection of drifting gratings (at low spatial frequencies), speed discrimination and detection of coherent dot motion. We found that some RD subjects (six out of 30) had impaired magnocellular function. Nevertheless, these RD subjects were also consistently impaired on a broad range of other perceptual tasks. The performance of the other subgroup of RD subjects on magnocellular tasks did not differ from that of controls. However, they did show impaired performance in both visual and auditory non‐magnocellular tasks requiring fine frequency discriminations. The stimuli used in these tasks were neither modulated in time nor briefly presented. We conclude that some RD subjects have generally impaired perceptual skills. Many RD subjects have more specific perceptual deficits; however, the ‘magnocellular’ level of description did not capture the nature of the perceptual difficulties in any of the RD individuals assessed by us.
Article
Claims that children with reading and oral language deficits have impaired perception of sequential sounds are usually based on psychophysical measures of auditory temporal processing (ATP) designed to characterise group performance. If we are to use these measures (e.g., the Tallal, 1980, Repetition Test) as the basis for intervention in language and literacy deficits, we need to demonstrate that they can effectively quantify individual differences. Therefore, questions of standardisation, reliability and construct validity can no longer be ignored. We explored these issues in three studies: (i) 52 Dyslexics and Good Readers aged 8 to 11 years performed a task requiring perception of rapid sequences (PRS) based on the Tallal Repetition Test; (ii) a subgroup of the initial sample was retested on the task three to four months later, and after extended practice; (iii) a further subgroup then completed a rate of auditory processing task using a backward recognition masking paradigm. With a standardised methodology, we were able to replicate previous results with the PRS task, and demonstrate moderate reliability of measurement across time and practice. However, there were large effects of exposure and practice, and the task did not seem useful for identifying absolute and continuing deficits in given individuals. Our results call into question the use of this type of task as an individual measure of ATP. Neither is it certain that it is capturing what is currently understood as ATP.
Article
Developmental dyslexics, individuals with an unexplained difficulty reading, have been shown to have deficits in phonological processing -- the awareness of the sound structure of words -- and, in some cases, a more fundamental deficit in rapid auditory processing. In addition, dyslexics show a disruption in white matter connectivity between posterior and frontal regions. These results give continued support for a neurobiological etiology of developmental dyslexia. However, more research will be required to determine the possible causal relationships between these neurobiological disruptions and dyslexia.
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Inferior auditory temporal processing has been postulated as causally linked to phonological processing deficits in disabled readers with concomitant oral language delay (LDRDs), and absent in specifically disabled readers with normal oral language (SRDs). This investigation compared SRDs, LDRDs and normal readers aged 7-10 years on measures of auditory temporal processing (temporal order judgement) and phonological decoding (nonword reading). LDRDs exhibited deficits in temporal order judgement compared with normal readers, from whom SRDs did not differ significantly. These findings suggest that auditory temporal processing and oral language are related; however, very large within-group variability in the auditory temporal processing data further suggests that this relationship prevails in only a proportion of disabled readers with concomitant oral language weakness. In nonword reading, LDRDs performed worst of all, but SRDs also exhibited significant deficits compared with normal readers. Taken together, our results preclude the conceptualisation of temporal processing deficits as the unitary cause of phonological and language deficits in disabled readers.
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We describe two studies that used repetition priming paradigms to investigate brain activity during the reading of single words. Functional magnetic resonance images were collected during a visual lexical decision task in which nonword stimuli were manipulated with regard to phonological properties and compared to genuine English words. We observed a region in left-hemisphere primary auditory cortex linked to a repetition priming effect. The priming effect activity was observed only for stimuli that sound like known words; moreover, this region was sensitive to strategic task differences. Thus, a brain region involved in the most basic aspects of auditory processing appears to be engaged in reading even when there is no environmental oral or auditory component.
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An adult with a unilateral precipitous severe high-frequency hearing loss displayed a selective auditory temporal resolution deficit in the poorer ear, despite excellent word recognition ability in quiet bilaterally. Word recognition performance was inferior in interrupted noise, reverberation, and time-compression conditions when stimuli were presented to the hearing-impaired ear and compared with performance for stimuli presented to the normal-hearing ear or that of normal-hearing listeners. It was suggested that a restricted listening bandwidth was responsible for the performance decrement on the tasks involving temporal resolution. This case illustrates the importance of employing temporal resolution tasks in an audiologic test battery. Such assessment tools may reveal deficits that otherwise may go unnoticed in light of excellent word recognition in quiet.
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We present a novel framework for the multimodal display of words using topological, appearance, and auditory representations. The methods are designed for effective language training and serve as a learning aid for individuals with dyslexia. Our topological code decomposes the word into its syllables and displays it graphically as a tree structure. The appearance code assigns color attributes and shape primitives to each letter and takes into account conditional symbol probabilities, code ambiguities, and phonologically confusable letter combinations. An additional auditory code assigns midi events to each symbol and thus generates a melody for each input string. The entire framework is based on information theory and utilizes a Markovian language model derived from linguistic analysis of language corpora for English, French, and German. For effective word repetition a selection controller adapts to the user's state and optimizes the learning process by minimizing error entropy. The performance of the method was evaluated in a large scale experimental study involving 80 dyslexic and non-dyslexic children. The results show significant improvements in writing skills in both groups after small amounts of daily training. Our approach combines findings from 3D computer graphics, visualization, linguistics, perception, psychology, and information theory.
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Development dyslexics perform differently from controls on a number of low level visual tasks. We carried out three experiments to explore some of these differences. Dyslexics have been found to have reduced luminance contrast sensitivity at mesopic luminance levels. We failed to replicate this finding at photopic luminance levels. We also compared the (photopic) coherent motion detection thresholds of groups of child and adult dyslexics with those of age matched controls. Dyslexics were significantly less sensitive to motion. The results are discussed in relation to a recent suggestion that developmental dyslexia may be associated with a magnocellular visual deficit.
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Increased interest and research into the possible neuropsychological bases of learning and behavior problems seen in children has been sustained in the past decade by promising results from researchers in the fields of learning disabilities, neuropsychology, neurophysiology, and cognitive psychology. Advances have been made in the neuropsychological assessment of children, accuracy of identification of specific subtypes of learning problems, identification and measurement of possible underlying neural mechanisms of childhood learning and behavioral disorders, and in the understanding of how these factors may interact.
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Resumo A dislexia é uma patologia no aprendizado da leitura e da escrita, cujas dificuldades não se justificam por ambiente social ou familiar desfavorecido, por algum déficit sensorial, por método de ensino ineficiente ou por baixos índices nas escalas de inteligência. Neste estudo realizou-se uma análise das condições estruturais e humanas na região de Vitória da Conquista na Bahia para a abordagem dessa dificuldade de aprendizado por meio de entrevistas a docentes atuantes no Ensino Fundamental I, entrevistas a estudantes matriculados no curso de Pedagogia em disciplinas de últimos semestres e levantamento da matriz curricular desse curso na universidade que oferece esse curso na cidade. De maneira geral, observamos neste estudo que, embora a literatura científica aponte para incidência de 5 a 10 % de aprendizes, não há entendimento e preparação para administração da dificuldade de aprendizado da leitura e da escrita conhecida como dislexia: a) na matriz curricular consta a disciplina Dificuldade de aprendizagem como optativa; b) docentes e estudantes afirmaram não se sentirem preparados para a administração dessa dificuldade de aprendizado e c) os estudantes não dispõem de estrutura satisfatória para eventuais intervenções. ************************************************************************************************************************************************************************************************************ Dyslexia approach in Vitória da Conquista region in Bahia: a review in the neuroscientific perspective Abstract: Dyslexia is an abnormality in the reading and writing learning, whose difficulties are not justified by disadvantaged social or family environment for some sensory deficit, by inefficient method of education or low levels in the intelligence scales. This study conducted an analysis of the structural and human conditions in the region of Vitória da Conquista in Bahia for the approach of this learning difficulties through interviews with teachers acting in elementary school, interviews with students enrolled in pedagogy courses in the disciplines of last semesters and lifting the curriculum of this course in the university offering this course in the city. Overall, this study observed that although the scientific literature point to incidence 5-10% of apprentices, there is no understanding and preparation for administration of learning difficulties in reading and writing known as dyslexia: a) the curriculum consists Difficulty learning the discipline as an optional; b) teachers and students said they did not feel prepared for the administration of this difficulty learning and c) the students not have satisfactory structure for possible interventions. Keywords: Dyslexia; Learning difficulties; Teaching
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Developmental dyslexia is suggested to affect approximately 5-10% of the population (Habib, 2000). The most influential theory of dyslexia is the phonological-deficit theory of dyslexia (Liberman, 1973; Stanovich, 1988; Snowling, 2000). An alternative explanation is that visual deficits can lead to reading difficulties (e.g. Stein & Walsh, 1997). To date the findings are mixed regarding the extent of visual deficits within the dyslexic population. Whether these problems represent a cause, correlation or consequence of the reading difficulty also remains highly controversial. The data presented throughout this Thesis examined the possibility that reading difficulties, associated with dyslexia, are linked to poor binocular coordination. In three experiments binocular eye movements of adults, typically developing children and children with dyslexia were measured while they read sentences or scanned dot string targets. In these experiments findings of previous binocular studies were replicated. Specifically, fixation disparity was modulated by the amplitude of the preceding saccade and the fixation position on the screen regardless of whether fixations and saccades were targeted to dots or words. Additionally, during the dot scanning task adult’s binocular coordination was improved in relation to children’s, but no reliable differences were found between the three groups. Critically, a significantly greater magnitude of fixation disparity was found for dyslexic children compared to typically developing children and adults during the reading task alone. The existence of linguistically modulated differences in binocular coordination for dyslexic children is a novel finding. The patterns of results from the three experiments indicate that poor binocular coordination in dyslexic children is restricted to reading linguistic material. Clearly, this represents a stimulus specific deficit in regard to binocular coordination, for children with dyslexia.
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Author cocitation analysis was used to explore ongoing changes in the intellectual structure of the hybrid prob- lem area of developmental dyslexia for the period 1994 - 1998, and to address ambiguities in results raised by an earlier study of these researchers for the years 1976 - 1993. Results suggest that: (1) discrepancies between the structure of the sociometric (personal) and author cocitation networks reflect real differences, not tempo- ral factors; (2) differences between cocitation patterns and reports in the literature, and corresponding delays in the visibility of emerging perspectives, are likely due to the "inertia" of aggregate cocitation data and/or by shifts by neuroscience-vision researchers to publication in more prominent journals; (3) a sharp rise in link den- sity for the neuroscience-vision subgroup indicates in- creased cohesiveness and growing maturation for this emerging perspective; (4) shifts in subgroup member- ship, link density, patterns of coauthorship, and multiple factor loadings suggest possible convergence between other subgroups in the network and identify individuals who may play boundary-spanning roles within the net- work; and (5) changing patterns of cocitation throughout the network suggest the increasing influence of studies relating to neurobiological mechanisms underlying dys- lexia. The possible contributions of such boundary span- ners in addressing the substantial information and com- munication challenges posed by the increased interdis- ciplinary character of scholarship in general also are discussed.
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The important role of working memory functions for reading and writing will be discussed together with the proven impairments of working memory performance in dyslexic individuals for visual and auditory presentation of stimuli with different paradigms and types of material. In the following paper, three studies will be introduced. The conceptual differentiation of these studies is based on the Baddeley and Hitch model (1974), with its specific modalities for incoming and maintaining information as well as on Cowan’s model (1995), with regard to automatic versus controlled executive functions during the generation of response and action. Thus, the central issue of the following studies is to investigate the importance and extent of assumed working memory impairments in dyslexic children with the focusing on the generality versus the specificity of these impairments. All three studies are conducted with samples of third grade dyslexic and non-dyslexic children. With the obtained results, we notice a dependency of working memory performance in dyslexic children on the training and language system (experiment 1), the specific type of modality (experiment 2) and on a specific kind of material (experiment 3). Therefore, the results of the three experiments cannot support the assumption of a general modality-, material-, and language-independent deficit in dyslexic individuals.
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Zusammenfassung: Fragestellung: Im vorliegenden Ubersichtsartikel werden Schwerpunkte der aktuellen Forschung zu neurobiologischen Korrelaten der Lese-Rechtschreibstorung (LRS) aufgezeigt. Methodik: Es wurden etwa 120 Artikel ausgewertet, die uberwiegend in den letzten sechs Jahren erschienen sind. Ergebnis: Es lassen sich drei Schwerpunkte unterscheiden. Der erste Forschungsschwerpunkt thematisiert ungewohnliche Asymmetrien der Plana temporalia und Auffalligkeiten des Corpus callosum. Die Vertreter des zweiten Ansatzes analysieren abnorme Aktivierungsmuster des linkshemispharischen Frontal- und Temporallappens. In diesem Zusammenhang wird eine Dysfunktion des linkshemispharischen Gyrus angularis diskutiert. Die Vertreter der dritten Storung untersuchen Auffalligkeiten im Bereich der Wahrnehmung. Sie vermuten ein globales Defizit der Verarbeitung schneller Reize und finden Korrelate der LRS in Defiziten subkortikaler Systeme der akustischen und visuellen Informationsverarbeitung. Schlussfolgerungen: Aufgr...
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Hand preference and sensitivity to coherent motion in random dot patterns were assessed in a large group of adult dyslexics and controls. The aims were to investigate further the hypotheses that dyslexia is associated with (a) anomalous lateralisation, and (b) an impairment of magnocellular visual processing; and in addition, to investigate a possible relationship between anomalous lateralisation and magnocellular function. Results showed that dyslexia was strongly associated with mixed hand preference, indicative of reduced cerebral lateralisation. Dyslexics also showed reduced visual motion sensitivity, consistent with an impairment of magnocellular visual function. However, independent of dyslexia, non-right-handedness was also associated with poor motion sensitivity, suggesting that there may be a more general relationship between impaired magnocellular function and reduced cerebral lateralisation.
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ABSTRACT Previous research,has suggested,that visual magnocellular,impairment,may,be characteristic,of up to 75% of developmentaldyslexics. In this study,we compared,18 adult dyslexics,and 18 controls on two tasks of putative visual magnocellular,function. We examined,whether,these tasks could discriminate,dyslexics,from controls and also the relationship between these measures and nonword reading, a sensitive measure of phonological,awareness.,Our results showed,that dyslexics were,significantly less sensitive than,controls for detection,of coherent motion,in random,dot kinematograms (RDK) and,also the highest,frequency,at which temporal,modulation,at full contrast,was detectable, the critical flicker fusion frequency (CFF). Across the two groups and within each group examined separately, motion and flicker sensitivity correlated strongly with nonword reading ability. Together, the temporal perception measures were able to discriminate 72.2% of the dyslexics from controls, so this type of visual deficit may be an important,feature of dyslexia. Our results support,the hypothesis,that dyslexics’ reading problems,are not entirely caused,by a specific deficit in language,processing. These visual deficits are also found,in younger,subjects; hence,visual temporal,perception measures,may,be used to identify children,at risk for dyslexia,prior to actual reading failure. Key words: dyslexia, magnocellular, flicker fusion, motion Visual deficits in developmentaldyslexia 3
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Is it necessary to posit separate, explicit distinctions between representations in order to account for dissociations between consonant and vowel processing? We argue that a cognitive model of speech production based on cumulative lower-level properties is not only sufficient but more parsimonious in accounting for aphasic and dysgraphic patient data. We re-examine a computational model of consonant and vowel processing based on phonological feature representations of phonemes, and show that models based on similar principles are sufficient to account for quantitative and qualitative aspects of the patient data. We argue that the facts that aphasic patients (i) are more likely to have impairment to consonant than vowel representations, (ii) demonstrate varying degrees of impairment to both consonants and vowels in an inverse relationship, and (iii) never indicate complete impairment to only vowels or consonants, are better accounted for in a model that assumes a continuum of representations of consonants and vowels than a model that explicitly encodes the consonant/vowel distinction.
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Background The performance of visual and auditory working memory together with different automated central executive functions was investigated on the basis of four computerized, adaptive task sets with measurement of accuracy and reaction time. Participants and procedure Eighty-six children selected from 192 dyslexic and nondyslexic children (mean age = 10.29 years) in Hong Kong and Leipzig were matched on intelligence by using the Culture Fair test (CFT 20) and age. The used reading and writing tests were language specific but scientifically similar. Four task sets with visual material (dot and line patterns) and auditory material (tone sequences) were adapted and randomly presented by a computer. Mean and maximum accuracy and speed parameters were measured. The hypotheses of dyslexia deficits and Chinese superiority in working memory performance on nonverbal material were examined. Results The Cantonese speaking children were found to have a working memory advantage in the speed measure on all four task sets with visual and auditory stimulus presentation, and in the accuracy measure on the auditory tasks only. Dyslexia deficits were only found in the Chinese sample for the maximum performance parameters and one auditory task set. In the German sample, the dyslexia deficits were found to be more generalized in the auditory matching and reproduction task sets concerning mean and maximum accuracy and speed parameters. Conclusions The novel approach in this study concerns the new paradigm of adaptive, time efficient testing of working memory functions with nonverbal, auditory and visual material.
Article
This study focused on visual-sequential and visuo-spatial functions in a group of 39 heavily dyslexic children, compared to a Control group. Mean age was 12.72 (SD 1.71). The dyslexia group was divided into three subgroups by language comprehension and mathematics skills. Only on a visual-sequential task was no difference seen between the groups. The main differences occurred between the two dyslexic subgroups with no language comprehension impairment, but with varying mathematics skills. Whereas the subgroup with good mathematics skills scored within the upper ranges, the mathematics-impaired subgroup showed significantly lower scores. The third dyslexic subgroup, with both language comprehension and mathematics impairments, performed within the norm. The study indicates a dissociation between language comprehension and visuo-spatial skills in dyslexia, which has implications for how variations in dyslexia should be understood. The results also show that the visuo-spatial impairments seen in one of the dyslexia subgroups lead to two ways of understanding mathematics impairment when it co-occurs with dyslexia: (1) as a visuo-spatial problem; (2) as a linguistic problem. These distinctions should imply different intervention strategies in dyslexia.
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