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 Sensitive period for cognitive repurposing of human visual cortex

2018 ◽  
Author(s):  
Shipra Kanjlia ◽  
Rashi Pant ◽  
Marina Bedny
Keyword(s):  
Visual Cortex ◽  
Sensory Loss ◽  
Sensitive Period ◽  
Human Cortex ◽  
Regional Specialization ◽  
Congenital Blindness ◽  
Functional Flexibility ◽  
Sensitive Periods ◽  
Congenitally Blind ◽  
Visual Cortices

AbstractStudies of sensory loss are a model for understanding the functional flexibility of human cortex. In congenital blindness, subsets of visual cortex are recruited during higher-cognitive tasks, such as language and math tasks. Is such dramatic functional repurposing possible throughout the lifespan or restricted to sensitive periods in development? We compared visual cortex function in individuals who lost their vision as adults (after age 17) to congenitally blind and sighted blindfolded adults. Participants took part in resting-state and task-based fMRI scans during which they solved math equations of varying difficulty and judged the meanings of sentences. Blindness at any age caused “visual” cortices to synchronize with specific fronto-parietal networks at rest. However, in task-based data, visual cortices showed regional specialization for math and language and load-dependent activity only in congenital blindness. Thus, despite the presence of long-range functional connectivity, cognitive repurposing of human cortex is limited by sensitive periods.

scholarly journals Naturalistic audio-movies reveal common spatial organization across “visual” cortices of different blind individuals

2021 ◽  
Author(s):  
Elizabeth Musz ◽  
Rita Loiotile ◽  
Janice Chen ◽  
Marina Bedny
Keyword(s):  
Visual Cortex ◽  
Visual Information ◽  
Spatial Organization ◽  
Activity Patterns ◽  
Auditory Stimuli ◽  
Spatial Activity ◽  
Pattern Similarity ◽  
Congenitally Blind ◽  
Visual Cortices ◽  
Blind Individuals

AbstractOccipital cortices of different sighted people contain analogous maps of visual information (e.g., foveal vs. peripheral space). In congenital blindness, “visual” cortices enhance responses to nonvisual stimuli. Do deafferented visual cortices of different blind people represent common informational maps? We leverage a naturalistic stimulus paradigm and inter-subject pattern similarity analysis to address this question. Blindfolded sighted (S, n=22) and congenitally blind (CB, n=22) participants listened to three auditory excerpts from movies; a naturalistic spoken narrative; and matched degraded auditory stimuli (i.e., shuffled sentences and backwards speech) while undergoing fMRI scanning. In a parcel-based whole brain analysis, we measured the spatial activity patterns evoked by each unique, ten-second segment of each auditory clip. We then compared each subject’s spatial pattern to that of all other subjects in the same group (CB or S) within and across segments. In both blind and sighted groups, segments of meaningful auditory stimuli produced distinctive patterns of activity that were shared across individuals. Crucially, only in the CB group, this segment-specific, cross-subject pattern similarity effect emerged in visual cortex, but only for meaningful naturalistic stimuli and not backwards speech. These results suggest that spatial activity patterns within deafferented visual cortices encode meaningful, segment-level information contained in naturalistic auditory stimuli, and that these representations are spatially organized in a similar fashion across blind individuals.Significance StatementRecent neuroimaging studies show that the so-called “visual” cortices activate during non-visual tasks in people who are born blind. Do the visual cortices of people who are born blind develop similar representational maps? While congenitally blind individuals listened to naturalistic auditory stimuli (i.e., sound clips from movies), distinct timepoints within each stimulus elicited unique spatial activity patterns in visual cortex, and these patterns were shared across different people. These findings suggest that in blindness, the visual cortices encode meaningful information embedded in naturalistic auditory signals in a spatially distributed manner, and that a common representational map can emerge in visual cortex independent of visual experience.

scholarly journals Sensitive Period for Cognitive Repurposing of Human Visual Cortex

2018 ◽  
Vol 29 (9) ◽  
pp. 3993-4005 ◽  
Author(s):  
Shipra Kanjlia ◽  
Rashi Pant ◽  
Marina Bedny
Keyword(s):  
Visual Cortex ◽  
Sensory Loss ◽  
Sensitive Period ◽  
Human Cortex ◽  
Regional Specialization ◽  
Congenital Blindness ◽  
Functional Flexibility ◽  
Sensitive Periods ◽  
Congenitally Blind ◽  
Visual Cortices

Abstract Studies of sensory loss are a model for understanding the functional flexibility of human cortex. In congenital blindness, subsets of visual cortex are recruited during higher-cognitive tasks, such as language and math tasks. Is such dramatic functional repurposing possible throughout the lifespan or restricted to sensitive periods in development? We compared visual cortex function in individuals who lost their vision as adults (after age 17) to congenitally blind and sighted blindfolded adults. Participants took part in resting-state and task-based fMRI scans during which they solved math equations of varying difficulty and judged the meanings of sentences. Blindness at any age caused “visual” cortices to synchronize with specific frontoparietal networks at rest. However, in task-based data, visual cortices showed regional specialization for math and language and load-dependent activity only in congenital blindness. Thus, despite the presence of long-range functional connectivity, cognitive repurposing of human cortex is limited by sensitive periods.

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.

scholarly journals Changes in thalamocortical connectivity as a potential mechanism of cross-modal plasticity in congenitally blind individuals

2018 ◽  
Author(s):  
Theo Marins ◽  
Maite Russo ◽  
Erika Rodrigues ◽  
jorge Moll ◽  
Daniel Felix ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Cortical Thickness ◽  
Visual Information ◽  
Brain Plasticity ◽  
Temporal Cortex ◽  
Occipital Cortex ◽  
Brain Structures ◽  
Congenitally Blind ◽  
Blind Individuals ◽  
Neuroimaging Techniques

ABSTRACTEvidence of cross-modal plasticity in blind individuals has been reported over the past decades showing that non-visual information is carried and processed by classical “visual” brain structures. This feature of the blind brain makes it a pivotal model to explore the limits and mechanisms of brain plasticity. However, despite recent efforts, the structural underpinnings that could explain cross-modal plasticity in congenitally blind individuals remain unclear. Using advanced neuroimaging techniques, we mapped the thalamocortical connectivity and assessed cortical thickness and integrity of white matter of congenitally blind individuals and sighted controls to test the hypothesis that aberrant thalamocortical pattern of connectivity can pave the way for cross-modal plasticity. We described a direct occipital takeover by the temporal projections from the thalamus, which would carry non-visual information (e.g. auditory) to the visual cortex in congenitally blinds. In addition, the amount of thalamo-occipital connectivity correlated with the cortical thickness of primary visual cortex (V1), supporting a probably common (or related) reorganization phenomena. Our results suggest that aberrant thalamocortical connectivity as one possible mechanism of cross-modal plasticity in blinds, with potential impact on cortical thickness of V1.SIGNIFICANT STATEMENTCongenitally blind individuals often develop greater abilities on spared sensory modalities, such as increased acuity in auditory discrimination and voice recognition, when compared to sighted controls. These functional gains have been shown to rely on ‘visual’ cortical areas of the blind brain, characterizing the phenomenon of cross-modal plasticity. However, its anatomical underpinnings in humans have been unsuccessfully pursued for decades. Recent advances of non-invasive neuroimaging techniques allowed us to test the hypothesis of abnormal thalamocortical connectivity in congenitally blinds. Our results showed an expansion of the thalamic connections to the temporal cortex over those that project to the occipital cortex, which may explain, the cross-talk between the visual and auditory systems in congenitally blind individuals.

scholarly journals Mental Imagery Follows Similar Cortical Reorganization as Perception: Intra-Modal and Cross-Modal Plasticity in Congenitally Blind

2018 ◽  
Vol 29 (7) ◽  
pp. 2859-2875 ◽  
Author(s):  
A W de Borst ◽  
B de Gelder
Keyword(s):  
Visual Cortex ◽  
Mental Imagery ◽  
Cortical Plasticity ◽  
Tactile Perception ◽  
Cortical Reorganization ◽  
Area V4 ◽  
Congenitally Blind ◽  
Early Visual Cortex ◽  
Blind Individuals ◽  
Discriminative Patterns

Abstract Cortical plasticity in congenitally blind individuals leads to cross-modal activation of the visual cortex and may lead to superior perceptual processing in the intact sensory domains. Although mental imagery is often defined as a quasi-perceptual experience, it is unknown whether it follows similar cortical reorganization as perception in blind individuals. In this study, we show that auditory versus tactile perception evokes similar intra-modal discriminative patterns in congenitally blind compared with sighted participants. These results indicate that cortical plasticity following visual deprivation does not influence broad intra-modal organization of auditory and tactile perception as measured by our task. Furthermore, not only the blind, but also the sighted participants showed cross-modal discriminative patterns for perception modality in the visual cortex. During mental imagery, both groups showed similar decoding accuracies for imagery modality in the intra-modal primary sensory cortices. However, no cross-modal discriminative information for imagery modality was found in early visual cortex of blind participants, in contrast to the sighted participants. We did find evidence of cross-modal activation of higher visual areas in blind participants, including the representation of specific-imagined auditory features in visual area V4.

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 A distinctive neural nexus in blind individuals supports Braille reading

2021 ◽  
Author(s):  
Ruxue WANG ◽  
Jiangtao GONG ◽  
Chenying ZHAO ◽  
Yingqing XU ◽  
Bo HONG
Keyword(s):  
Visual Cortex ◽  
Functional Connectivity ◽  
Frontal Cortex ◽  
Reading Proficiency ◽  
Occipital Cortex ◽  
Resting State Functional Connectivity ◽  
Crossmodal Plasticity ◽  
Blind Individuals ◽  
Language Areas

In the absence of visual input, occipital 'visual' cortex of blind people has been found to be engaged in non-visual higher cognitive tasks. Although the increased functional connectivity between 'visual' cortex and frontal cortex in the blind has been observed, the specific organization and functional role of this connectivity change remain to be elucidated. Here, we tested resting-state functional connectivity for primary 'visual' cortex (V1) and higher-tier lateral occipital cortex (LOC) in people with acquired blindness, and found an enhanced connectivity between the LOC but not V1 and typical frontal language areas - the inferior frontal cortex (IFC). In fact, the left-lateralized LOC-IFC connectivity strength predicted blind individuals' natural Braille reading proficiency. Furthermore, an increased bidirectional information flow between the left LOC and IFC was observed during a natural Braille reading task. In particular, the task-relevant modulation of the top-down communication from left IFC to LOC was significantly stronger than that of the bottom-up communication. Altogether, our study identified a distinctive neural nexus, LOC-IFC connection, and its behavioral significance in the acquired blind, revealing the neural correlates of the crossmodal plasticity in their 'visual' cortex underlying natural Braille reading.

Body Movement and Verbal Encoding in the Congenitally Blind

1974 ◽  
Vol 39 (1) ◽  
pp. 279-293 ◽  
Author(s):  
Thomas Blass ◽  
Norbert Freedman ◽  
Irving Steingart
Keyword(s):  
Motor Activity ◽  
Verbal Fluency ◽  
Body Movement ◽  
Hand Movements ◽  
Complex Sentences ◽  
Sensory Experiences ◽  
Congenitally Blind ◽  
Continuous Body ◽  
Blind Individuals

The purpose of the study was to examine the prevalence of object- and body-focused hand movements of the congenitally blind individuals engaged in an encoding task and to determine the relation of these movements to verbal performance. Ten Ss participated in a 5-min. videotaped monologue. The video portion was coded for hand movements using Freedman's categories of analysis. The audio portion was scored for grammatical complexity according to a system developed by Steingart and Freedman. It was found that: (1) Blind Ss engaged only in body-focused movements; object-focused movements were almost completely absent. (2) Blind Ss displayed significantly greater amounts of body-focused (primarily finger-to-hand) movements than a group of sighted Ss observed in a previous study. (3) There was a correlation of .51 between finger-to-hand movements and verbal fluency and a correlation of –.53 between body-touching and verbal fluency. (4) Ss with a prevalence of finger-to-hand movements showed significantly greater language skill at encoding complex sentences which portray descriptions of patterned, interrelationships among experiences, while Ss with a predominance of continuous body touching gave a less skillful language product in this regard. The findings indicate the central role of motor activity in ongoing thought construction. They also indicate that for the blind, finger-to-hand motions contribute to the evocation of sensory experiences as a necessary pre-condition for linguistic representation.

scholarly journals Spoken language comprehension activates the primary visual cortex

2020 ◽  
Author(s):  
Anna Seydell-Greenwald ◽  
Xiaoying Wang ◽  
Elissa Newport ◽  
Yanchao Bi ◽  
Ella Striem-Amit
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Neural Plasticity ◽  
Spoken Language ◽  
Functional Change ◽  
Congenitally Blind ◽  
Intact Brain ◽  
Speech Control ◽  
Language Activation ◽  
Blind Individuals

AbstractCurrent accounts of neural plasticity emphasize the role of connectivity and conserved function in determining a neural tissue’s functional role even after atypical early experiences. However, in apparent conflict with this view, studies of congenitally blind individuals have also suggested that language activates primary visual cortex, with no evidence of major changes in anatomical connectivity that could explain this apparent drastic functional change in what is typically a low-level visual area. To reconcile what appears to be unprecedented functional reorganization in V1 with known accounts of plasticity limitations, we tested whether primary visual cortex also responds to spoken language in sighted individuals. We found that primary visual cortex was activated by comprehensible speech as compared to a reversed speech control task, in a left-lateralized and focal manner, in sighted individuals. Importantly, left V1 activation was also significant and comparable for abstract and concrete words, precluding a visual imagery account of such activation. Together these findings suggest that primary visual cortex responds to verbal information in the typically developed brain, potentially to predict visual input. This capability might be the basis for the strong V1 language activation observed in people born blind, re-affirming the notion that plasticity is guided by pre-existing connectivity and abilities in the intact brain.

Sign in / Sign up

Export Citation Format

Share Document