scholarly journals On Synchronizing Coupled Retinogeniculocortical Pathways: A Toy Model

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
B. L. Mayer ◽  
L. H. A. Monteiro
Keyword(s):  
Neural Network ◽  
Visual Cortex ◽  
Corpus Callosum ◽  
Neuronal Activity ◽  
Network Topology ◽  
Cerebral Hemisphere ◽  
State Transition ◽  
Regular Lattice ◽  
Visual Cortices

A Newman-Watts graph is formed by including random links in a regular lattice. Here, the emergence of synchronization in coupled Newman-Watts graphs is studied. The whole neural network is considered as a toy model of mammalian visual pathways. It is composed by four coupled graphs, in which a coupled pair represents the lateral geniculate nucleus and the visual cortex of a cerebral hemisphere. The hemispheres communicate with each other through a coupling between the graphs representing the visual cortices. This coupling makes the role of the corpus callosum. The state transition of neurons, supposed to be the nodes of the graphs, occurs in discrete time and it follows a set of deterministic rules. From periodic stimuli coming from the retina, the neuronal activity of the whole network is numerically computed. The goal is to find out how the values of the parameters related to the network topology affect the synchronization among the four graphs.

Tms in Migraine

2012 ◽  
Author(s):  
Jean Schoenen ◽  
Valentin Bohotin ◽  
Alain Maertens De Noordhout
Keyword(s):  
Cerebral Cortex ◽  
Visual Cortex ◽  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Event Related Potential ◽  
Visual Cortices ◽  
Multidisciplinary Studies ◽  
Migraine Pathophysiology ◽  
Cortical Dysfunction

Transcranial magnetic stimulation (TMS) has been used to search for cortical dysfunction in migraine. Both, the motor and the visual cortices have been explored in this area. This article reviews and discusses the results of the various studies performed in migraine patients with TMS of motor or visual cortices. The majority of evoked and event-related potential studies in migraine have shown two abnormalities: increased amplitude of grand averaged responses and lack of habituation in successive blocks of averaged responses with decreased amplitude in the first block. These abnormalities suggest that the excitability state of the cerebral cortex, particularly of the visual cortex, is abnormal in migraineurs between attacks. The use of TMS to assess motor and visual cortex excitability has yielded conflicting results, which could be due to methodological differences. Taken together, all studies indicate that the changes in cortical reactivity are more complex in migraineurs than initially thought and suggest that both larger multidisciplinary studies and focused analyses of subgroups of patients with more refined clinical phenotypes are necessary to disentangle the role of the cerebral cortex in migraine pathophysiology.

scholarly journals “Visual” Cortices of Congenitally Blind Adults Respond to Executive Demands Authors

2018 ◽  
Author(s):  
Rita E. Loiotile ◽  
Marina Bedny
Keyword(s):  
Visual Cortex ◽  
Executive Control ◽  
Alternative Hypothesis ◽  
Human Cortex ◽  
Cortex Area ◽  
Congenitally Blind ◽  
Visual Cortices ◽  
Underlying Mechanisms ◽  
Blind Individuals

AbstractHow functionally flexible is human cortex? In congenitally blind individuals, “visual” cortices are active during auditory and tactile tasks. The cognitive role of these responses and the underlying mechanisms remain uncertain. A dominant view is that, in blindness, “visual” cortices process information from low-level auditory and somatosensory systems. An alternative hypothesis is that higher-cognitive fronto-parietal systems take over “visual” cortices. We report that, in congenitally blind individuals, right-lateralized “visual” cortex responds to executiveload in a go/no-go task. These right-lateralized occipital cortices of blind, but not sighted, individuals mirrored the executive-function pattern observed in fronto-parietal systems. In blindness, the same “visual” cortex area, at rest, also increases its synchronization with prefrontal executive control regions and decreases its synchronization with auditory and sensorimotor cortices. These results support the hypothesis of top-down fronto-parietal takeover of “visual” cortices, and suggest that human cortex is highly flexible at birth.

scholarly journals Effect of corpus callosum agenesis on the language network in children and adolescents

2021 ◽  
Author(s):  
Lisa Bartha-Doering ◽  
Ernst Schwartz ◽  
Kathrin Kollndorfer ◽  
Florian Ph. S. Fischmeister ◽  
Astrid Novak ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Corpus Callosum ◽  
Network Connectivity ◽  
Functional Language ◽  
Healthy Controls ◽  
Language Abilities ◽  
Verbal Abilities ◽  
Left And Right ◽  
Language Network

AbstractThe present study is interested in the role of the corpus callosum in the development of the language network. We, therefore, investigated language abilities and the language network using task-based fMRI in three cases of complete agenesis of the corpus callosum (ACC), three cases of partial ACC and six controls. Although the children with complete ACC revealed impaired functions in specific language domains, no child with partial ACC showed a test score below average. As a group, ACC children performed significantly worse than healthy controls in verbal fluency and naming. Furthermore, whole-brain ROI-to-ROI connectivity analyses revealed reduced intrahemispheric and right intrahemispheric functional connectivity in ACC patients as compared to controls. In addition, stronger functional connectivity between left and right temporal areas was associated with better language abilities in the ACC group. In healthy controls, no association between language abilities and connectivity was found. Our results show that ACC is associated not only with less interhemispheric, but also with less right intrahemispheric language network connectivity in line with reduced verbal abilities. The present study, thus, supports the excitatory role of the corpus callosum in functional language network connectivity and language abilities.

scholarly journals On the Role of Structured Pruning for Neural Network Compression

2021 ◽  
Author(s):  
Andrea Bragagnolo ◽  
Enzo Tartaglione ◽  
Attilio Fiandrotti ◽  
Marco Grangetto
Keyword(s):  
Neural Network ◽  
Network Compression
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