Figure 2 - uploaded by Chantel S Prat
Content may be subject to copyright.
Four indicators of posterior RH (RSTSp and RTPJ) compensatory activity contralateral to the rTMS site. The highlighted region (brown circle) indicates a convergence of several measures including an increase in synchronization with the medial frontal compensatory region, a greater activation following rTMS and correlations with RSPAN and behavioral improvement following rTMS.
Source publication
This study examined how the brain system adapts and reconfigures its information processing capabilities to maintain cognitive performance after a key cortical center [left posterior superior temporal gyrus (LSTGp)] is temporarily impaired during the performance of a language comprehension task. By applying repetitive transcranial magnetic stimulat...
Contexts in source publication
Context 1
... Evidence of the Compensatory Role of the Posterior Right Hemisphere (RSTSp and RTPJ) There were 4 indicators of the centrality of the posterior right hemisphere in the brain system's adaptive response to the rTMS in 4 proximal RTPJ areas. First, as noted above, RSTGp increased its synchronization with MedFG (shown by yellow region in Fig. 2). Secondly, the degree of RTPJ activation was correlated with working memory capacity for language (RSPAN) as described above (shown by green regions). Thirdly, RTPJ (MNI centroid 46, −58, 34) was one of the few areas showing an increase in activation (t (24) = 3.47, P < 0.001 uncorrected) in response to rTMS, indicated by the red ...
Context 2
... the degree of RTPJ activation was correlated with working memory capacity for language (RSPAN) as described above (shown by green regions). Thirdly, RTPJ (MNI centroid 46, −58, 34) was one of the few areas showing an increase in activation (t (24) = 3.47, P < 0.001 uncorrected) in response to rTMS, indicated by the red region in Figure 2. (This increase was assessed with the contrast to the RH-rTMS control group.) ...
Context 3
... in Figure 2. (This increase was assessed with the contrast to the RH-rTMS control group.) Fourthly, the activation in a superior RTPJ location was correlated with the speed-up in successful completion of the task as measured by faster com- prehension probe RTs following rTMS than before (r (16) = 0.606, P < 0.001 uncorrected; blue regions in Fig. 2; MNI centroids 40, −62, 42 and 50, −44, 39). These 4 indi- cators of the posterior right hemisphere centrality in compen- sation all occur proximally to each other, having a mean distance 7.7 mm to the centroid of their centroids. The pos- terior right-hemisphere region supports the dynamically con- structed compensatory network (whose ...
Citations
... The most popular cognitive domain for interleaved TMS-fMRI studies to date is attention, and most experiments targeted the right hemisphere. The language domain has not been investigated so far (compare [84]). ...
... Specifically, it is unclear whether the conclusions obtained from studies conducted during rest should generalize to studies where the targeted brain area is already engaged in a task and thus may have elevated BOLD at the time of stimulation. To date, 10 papers reporting on 11 experiments have employed concurrent TMS-fMRI during a task and reported either presence or absence of local BOLD activation (Nahas et al., 2001;Sack et al., 2007;Bestmann et al., 2008cBestmann et al., , 2010Feredoes et al., 2011;Heinen et al., 2011Heinen et al., , 2014Ricci et al., 2012;Mason et al., 2014;Leitão et al., 2015Leitão et al., , 2017. Of these, five experiments resulted in TMS-induced BOLD activity at the site of stimulation, while six experiments led to no such activity (Table 4). ...
... Of these, four studies employed various attention tasks and delivered TMS to attention-related brain areas such as the superior parietal lobule (Sack et al., 2007), angular gyrus , posterior parietal cortex (Ricci et al., 2012), and occipital cortex (Leitão et al., 2017) in neurologically intact subjects (note that the last study reported significant BOLD activation in a separate condition that targeted IPS). Another study targeted Wernicke's area during a sentence comprehension task again in normal subjects (Mason et al., 2014). The remaining study employed a motor task and stimulated PMd in a group of stroke patients (Bestmann et al., 2010). ...
... The remaining study employed a motor task and stimulated PMd in a group of stroke patients (Bestmann et al., 2010). Four studies employed only second-level analyses (Sack et al., 2007;Bestmann et al., 2010;Mason et al., 2014;Leitão et al., 2017), one employed first-level analyses (Ricci et al., 2012), and only one employed ROI analyses with the ROIs defined based on the targeted coordinates . Unfortunately, the lack of precise localization in the majority of these studies makes it hard to draw firm conclusions from them regarding the direct neural effects of TMS on the BOLD activity at the site of stimulation. ...
Transcranial magnetic stimulation (TMS) is widely used for understanding brain function in neurologically intact subjects and for the treatment of various disorders. However, the precise neurophysiological effects of TMS at the site of stimulation remain poorly understood. The local effects of TMS can be studied using concurrent TMS-functional magnetic resonance imaging (fMRI), a technique where TMS is delivered during fMRI scanning. However, although concurrent TMS-fMRI was developed over 20 years ago and dozens of studies have used this technique, there is still no consensus on whether TMS increases blood oxygen level-dependent (BOLD) activity at the site of stimulation. To address this question, here we review all previous concurrent TMS-fMRI studies that reported analyses of BOLD activity at the target location. We find evidence that TMS increases local BOLD activity when stimulating the primary motor (M1) and visual (V1) cortices but that these effects are likely driven by the downstream consequences of TMS (finger twitches and phosphenes). However, TMS does not appear to increase BOLD activity at the site of stimulation for areas outside of the M1 and V1 when conducted at rest. We examine the possible reasons for such lack of BOLD signal increase based on recent work in nonhuman animals. We argue that the current evidence points to TMS inducing periods of increased and decreased neuronal firing that mostly cancel each other out and therefore lead to no change in the overall BOLD signal.
... This signal suppression effect fits with the traditional use of temporary virtual lesions in a healthy brain. Indeed, virtual lesions are classically associated with a temporary inactivation of a population of neurons (Sack et al., 2007) (Harris et al., 2008) (Mullin and Steeves, 2013) (Mason et al., 2014), thereby impairing behaviour (Burton et al., (which was not certified by peer review) is the author/funder. All rights reserved. ...
... /2022 2009) (Perini et al., 2012) (Schwarzkopf et al., 2011). Prior studies using concurrent or interleaved TMS and fMRI have described a localized decreased BOLD signal as being the neural signature of TMS-induced virtual lesion under different contexts (Sack et al., 2007) (Harris et al., 2008) (Mullin and Steeves, 2013) (Mason et al., 2014). ...
Understanding the causal relationship between a focal lesion and network (re)organization is crucial to accurately predict the resulting large-scale symptoms of a lesion. In this study, we applied short trains of 10 Hz TMS to healthy participants over the early visual areas (EVA) or the medio-temporal area (hMT+/MT) during a motion discrimination task and at rest, while concurrent fMRI was acquired. TMS applied in the early stage of motion processing induced a specific deficit in judging motion direction in both sites, while global motion perception was preserved. This was associated with a common suppression of local brain activity and network activity. In contrast, we report distinct topological network properties depending on the disrupted site. Networks associated with EVA perturbation displayed a more robust and efficient functional reorganization, suggesting that EVA might be more resilient to focal perturbations. While contributing to a better understanding of the impact and potential mechanisms of TMS perturbation, these results provide a model for focal lesions in the visual motion processing system.
Highlights
TMS-induced perturbation of the early visual areas (EVA) or the mediotemporal area (hMT+/V5) area selectively impairs motion direction discrimination.
The TMS perturbation is associated with a local down-scaling of BOLD activity in both areas, potentially specific to task-related neuronal populations during motion discrimination.
The two visual areas display distinct topological networks’ adaptations in response to TMS, reflecting different levels of networks resilience to a focal lesion.
TMS-fMRI coupling can be used to assess ‘disconnectomics’ and to precisely map how a local perturbation propagates to large-scale behavioural deficits.
Graphical abstract
... 1. Wernicke's area. NOTE: The stimulation electrode placement that best corresponds to Wernicke's area is CP5 according to the extended International 10-20 system for EEG 16,17 . 1. To locate this location in the absence of an electrode cap, follow the standard 10-20 system procedures. ...
Language is a highly important yet poorly understood function of the human brain. While studies of brain activation patterns during language comprehension are abundant, what is often critically missing is causal evidence of brain areas' involvement in a particular linguistic function,
not least due to the unique human nature of this ability and a shortage of neurophysiological tools to study causal relationships in the human brain noninvasively. Recent years have seen a rapid rise in the use of transcranial direct current stimulation (tDCS) of the human brain, an
easy, inexpensive and safe noninvasive technique that can modulate the state of the stimulated brain area (putatively by shifting excitation/ inhibition thresholds), enabling a study of its particular contribution to specific functions. While mostly focusing on motor control, the use of tDCS is becoming more widespread in both basic and clinical research on higher cognitive functions, language included, but the procedures for its application remain variable. Here, we describe the use of tDCS in a psycholinguistic word-learning experiment. We present the techniques
and procedures for application of cathodal and anodal stimulation of core language areas of Broca and Wernicke in the left hemisphere of the human brain, describe the procedures of creating balanced sets of psycholinguistic stimuli, a controlled yet naturalistic learning regime, and a comprehensive set of techniques to assess the learning outcomes and tDCS effects. As an example of tDCS application, we show that cathodal stimulation of Wernicke's area prior to a learning session can impact word learning efficiency. This impact is both present immediately after learning and, importantly, preserved over longer time after the physical effects of stimulation wear off, suggesting that tDCS can have long-term influence on linguistic storage and representations in the human brain.
... Together, Broca's area plays an important role in processing of verbal information [153]. Wernicke's area is traditionally thought to be located in the posterior part of the superior temporal gyrus [STG], which is involved in the comprehension or understanding of written and spoken language [154]. Some studies have showed that the MTG is involved in the retrieval of lexical syntactic information [155]. ...
Many brain-based disorders are traditionally diagnosed based on clinical interviews and behavioral assessments, which are recognized to be largely imperfect. Therefore, it is necessary to establish neuroimaging-based biomarkers to improve diagnostic precision. Resting-state functional magnetic resonance imaging (rs-fMRI) is a promising technique for the characterization and classification of varying disorders. However, most of these classification methods are supervised, i.e., they require a priori clinical labels to guide classification. In this study, we adopted various unsupervised clustering methods using static and dynamic rs-fMRI connectivity measures to investigate whether the clinical diagnostic grouping of different disorders is grounded in underlying neurobiological and phenotypic clusters. In order to do so, we derived a general analysis pipeline for identifying different brain-based disorders using genetic algorithm-based feature selection, and unsupervised clustering methods on four different datasets; three of them—ADNI, ADHD-200, and ABIDE—which are publicly available, and a fourth one—PTSD and PCS—which was acquired in-house. Using these datasets, the effectiveness of the proposed pipeline was verified on different disorders: Attention Deficit Hyperactivity Disorder (ADHD), Alzheimer's Disease (AD), Autism Spectrum Disorder (ASD), Post-Traumatic Stress Disorder (PTSD), and Post-Concussion Syndrome (PCS). For ADHD and AD, highest similarity was achieved between connectivity and phenotypic clusters, whereas for ASD and PTSD/PCS, highest similarity was achieved between connectivity and clinical diagnostic clusters. For multi-site data (ABIDE and ADHD-200), we report site-specific results. We also reported the effect of elimination of outlier subjects for all four datasets. Overall, our results suggest that neurobiological and phenotypic biomarkers could potentially be used as an aid by the clinician, in additional to currently available clinical diagnostic standards, to improve diagnostic precision. Data and source code used in this work is publicly available at https://github.com/xinyuzhao/identification-of-brain-based-disorders.git.
... Del mismo modo, la mayoría de los estudios están centrados en población infantil (Cruz & Aguado, 2014;Kovachy, Adams, Tamaresis, & Feldman, 2015;Torres & Granados, 2014;Franco, Cárdenas & Santrich, 2016), lo cual es comprensible porque es esta la etapa en la que se empieza a gestar la competencia lectora; sin embargo, se ha dejado un poco de lado el estudio en la población adulta en la que claramente, este proceso se sigue cimentando, como lo demostraron Damagistri, Richards y Canet (2014), quienes en un estudio demostraron que en la adolescencia la comprensión lectora, la memoria de trabajo y la inhibición mejoran. Por otra parte, dada la evidencia científica, es fácil deducir que gracias al aprendizaje y a la plasticidad cerebral, la CL se va afinando aún más ya en la etapa adulta (Johnson & Li, 2014;Mason, Prat & Just, 2014; Purcella, Sheaa, & ...
Este escrito de reflexión describe el efecto de las tecnologías de información y la comunicación en la educación y las Ciencias Sociales. Igualmente,
muestra cómo su impacto en los procesos de enseñanza y de
aprendizaje, han generado cambios en los roles y maneras de desarrollar
las sesiones de clases dentro y fuera del aula.
... 1 Our brain is capable of recovery after massive loss of neurons, as can happen in an accident. 2 Two factors contribute to these abilities. First, the brain exhibits high redundancy, which is studied by neuroscientists within the framework of population coding. ...
The brain, which uses redundancy and continuous learning to overcome the unreliability of its components, provides a promising path to building computing systems that are robust to the unreliability of their constituent nanodevices. In this work, we illustrate this path by a computing system based on population coding with magnetic tunnel junctions that implement both neurons and synaptic weights. We show that equipping such a system with continuous learning enables it to recover from the loss of neurons and makes it possible to use unreliable synaptic weights (i.e. low energy barrier magnetic memories). There is a tradeoff between power consumption and precision because low energy barrier memories consume less energy than high barrier ones. For a given precision, there is an optimal number of neurons and an optimal energy barrier for the weights that leads to minimum power consumption.
... Adaptation involves three synchronization centers: the contralateral homolog of the area receiving rTMS (i. e. the right STGp), areas adjacent to the rTMS site and the medial frontal gyrus, a region involved in discourse monitoring (Mason et al., 2014). Because of such insights on the role of the language network in epilepsy-related cognitive outcomes, particularly its adaptive response to injury, this network may be a therapeutic target to prevent cognitive impairment in epilepsy. ...
Epilepsy is a paroxysmal neurological disorder characterized by recurrent and unprovoked seizures affecting approximately 50 million people worldwide. Cognitive dysfunction induced by seizures is a severe comorbidity of epilepsy and epilepsy syndromes and reduces patients’ quality of life. Seizures, along with accompanying histopathological and pathophysiological changes, are associated with cognitive comorbidities. Advances in imaging technology and computing allow anatomical and topological changes in neural networks to be visualized. Anatomical components including the hippocampus, amygdala, cortex, corpus callosum (CC), cerebellum and white matter (WM) are the fundamental components of seizure- and cognition-related topological networks. Damage to these structures and their substructures results in worsening of epilepsy symptoms and cognitive dysfunction. In this review article, we survey structural, network changes and topological alteration in different regions of the brain and in different epilepsy and epileptic syndromes, and discuss what these changes may mean for cognitive outcomes related to these disease states.
... Del mismo modo, la mayoría de los estudios están centrados en población infan l (Cruz & Aguado, 2014;Kovachy, Adams, Tamaresis, & Feldman, 2015;Torres & Granados, 2014;Franco, Cárdenas & Santrich, 2016), lo cual es comprensible porque es esta la etapa en la que se empieza a gestar la competencia lectora; sin embargo, se ha dejado un poco de lado el estudio en la población adulta en la que claramente, este proceso se sigue cimentando, como lo demostraron Damagistri, Richards y Canet (2014), quienes en un estudio demostraron que en la adolescencia la comprensión lectora, la memoria de trabajo y la inhibición mejoran. Por otra parte, dada la evidencia cien fi ca, es fácil deducir que gracias al aprendizaje y a la plas cidad cerebral, la CL se va afi nando aún más ya en la etapa adulta (Johnson & Li, 2014;Mason, Prat & Just, 2014;Purcella, Sheaa, & ...
... mejoran. Por otra parte, dada la evidencia cien fi ca, es f?cil deducir que gracias al aprendizaje y a la plas cidad cerebral, la CL se va afi nando a?n m?s ya en la etapa adulta (Johnson & Li, 2014;Mason, Prat & Just, 2014;Purcella, Sheaa, & Rappa, 2014), en la que esta competencia es fundamental, especialmente en quienes deciden emprender una carrera universitaria. Sin embargo, se requieren m?s estudios con este po de poblaci?n. ...
