scholarly journals Reorganization of Sound Location Processing in the Auditory Cortex of Blind Humans

2019 ◽  
Vol 30 (3) ◽  
pp. 1103-1116
Author(s):  
Kiki van der Heijden ◽  
Elia Formisano ◽  
Giancarlo Valente ◽  
Minye Zhan ◽  
Ron Kupers ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Temporal Cortex ◽  
Occipital Cortex ◽  
Spatial Processing ◽  
Planum Temporale ◽  
Sound Location ◽  
Activation Patterns ◽  
Spatial Tasks ◽  
Blind Individuals ◽  
Blind Humans

Abstract Auditory spatial tasks induce functional activation in the occipital—visual—cortex of early blind humans. Less is known about the effects of blindness on auditory spatial processing in the temporal—auditory—cortex. Here, we investigated spatial (azimuth) processing in congenitally and early blind humans with a phase-encoding functional magnetic resonance imaging (fMRI) paradigm. Our results show that functional activation in response to sounds in general—independent of sound location—was stronger in the occipital cortex but reduced in the medial temporal cortex of blind participants in comparison with sighted participants. Additionally, activation patterns for binaural spatial processing were different for sighted and blind participants in planum temporale. Finally, fMRI responses in the auditory cortex of blind individuals carried less information on sound azimuth position than those in sighted individuals, as assessed with a 2-channel, opponent coding model for the cortical representation of sound azimuth. These results indicate that early visual deprivation results in reorganization of binaural spatial processing in the auditory cortex and that blind individuals may rely on alternative mechanisms for processing azimuth position.

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 Functional preference for object sounds but not for voices in the occipito-temporal cortex of early blind individuals

2017 ◽  
Author(s):  
Giulia Dormal ◽  
Maxime Pelland ◽  
Mohamed Rezk ◽  
Esther Yakobov ◽  
Franco Lepore ◽  
...  
Keyword(s):  
Temporal Cortex ◽  
Primary Auditory Cortex ◽  
Familiar Object ◽  
Occipital Cortex ◽  
Functional Coupling ◽  
Level Control ◽  
Crossmodal Plasticity ◽  
Categorical Responses ◽  
The Right ◽  
Blind Individuals

AbstractSounds activate occipital regions in early blind individuals. How different sound categories map onto specific regions of the occipital cortex remains however debated. We used fMRI to characterize brain responses of early blind and sighted individuals to familiar object sounds, human voices and their respective low-level control sounds. Sighted participants were additionally tested when viewing pictures of faces, objects and phase-scrambled control pictures. In both early blind and sighted, a double dissociation was evidenced in bilateral auditory cortices between responses to voices and object sounds: voices elicited categorical responses in bilateral superior temporal sulci while object sounds elicited categorical responses along the lateral fissure bilaterally, including the primary auditory cortex and planum temporale. Outside of the auditory regions, object sounds additionally elicited categorical responses in left lateral and ventral occipito-temporal regions in both groups. These regions also showed response preference for images of objects in the sighted, thus suggesting a functional specialization in these regions that is independent of sensory input and visual experience. Between-group comparisons revealed that only in the blind group, categorical responses to object sounds extended more posteriorly into the occipital cortex. Functional connectivity analyses evidenced a selective increase in the functional coupling between these reorganized regions and regions of the ventral occipito-temporal cortex in the early blind. In contrast, vocal sounds did not elicit preferential responses in the occipital cortex in either group. Nevertheless, enhanced voice-selective connectivity between the left temporal voice area and the right fusiform gyrus were found in the blind. Altogether, these findings suggest that separate auditory categories are not equipotent in driving selective auditory recruitment of occipito-temporal regions in the absence of developmental vision, highlighting domain-region constraints on the expression of crossmodal plasticity.

scholarly journals Decoding Spatial Versus Non-spatial Processing in Auditory Working Memory

2021 ◽  
Vol 15 ◽  
Author(s):  
Mira Erhart ◽  
Stefan Czoschke ◽  
Cora Fischer ◽  
Christoph Bledowski ◽  
Jochen Kaiser
Keyword(s):  
Working Memory ◽  
Multivariate Analysis ◽  
Spatial Information ◽  
Temporal Cortex ◽  
Spatial Processing ◽  
Whole Brain ◽  
Activation Patterns ◽  
Spatial Sound ◽  
Stimulus Features ◽  
Sound Features

ObjectiveResearch on visual working memory has shown that individual stimulus features are processed in both specialized sensory regions and higher cortical areas. Much less evidence exists for auditory working memory. Here, a main distinction has been proposed between the processing of spatial and non-spatial sound features. Our aim was to examine feature-specific activation patterns in auditory working memory.MethodsWe collected fMRI data while 28 healthy adults performed an auditory delayed match-to-sample task. Stimuli were abstract sounds characterized by both spatial and non-spatial information, i.e., interaural time delay and central frequency, respectively. In separate recording blocks, subjects had to memorize either the spatial or non-spatial feature, which had to be compared with a probe sound presented after a short delay. We performed both univariate and multivariate comparisons between spatial and non-spatial task blocks.ResultsProcessing of spatial sound features elicited a higher activity in a small cluster in the superior parietal lobe than did sound pattern processing, whereas there was no significant activation difference for the opposite contrast. The multivariate analysis was applied using a whole-brain searchlight approach to identify feature-selective processing. The task-relevant auditory feature could be decoded from multiple brain regions including the auditory cortex, posterior temporal cortex, middle occipital gyrus, and extended parietal and frontal regions.ConclusionIn summary, the lack of large univariate activation differences between spatial and non-spatial processing could be attributable to the identical stimulation in both tasks. In contrast, the whole-brain multivariate analysis identified feature-specific activation patterns in widespread cortical regions. This suggests that areas beyond the auditory dorsal and ventral streams contribute to working memory processing of auditory stimulus features.

scholarly journals Development of visual category selectivity in ventral visual cortex does not require visual experience

2017 ◽  
Vol 114 (22) ◽  
pp. E4501-E4510 ◽  
Author(s):  
Job van den Hurk ◽  
Marc Van Baelen ◽  
Hans P. Op de Beeck
Keyword(s):  
Visual Cortex ◽  
Auditory Cortex ◽  
Visual Processing ◽  
Visual Experience ◽  
Temporal Cortex ◽  
Primary Auditory Cortex ◽  
Extrastriate Cortex ◽  
Striking Similarity ◽  
Visual Responses ◽  
Blind Individuals

To what extent does functional brain organization rely on sensory input? Here, we show that for the penultimate visual-processing region, ventral-temporal cortex (VTC), visual experience is not the origin of its fundamental organizational property, category selectivity. In the fMRI study reported here, we presented 14 congenitally blind participants with face-, body-, scene-, and object-related natural sounds and presented 20 healthy controls with both auditory and visual stimuli from these categories. Using macroanatomical alignment, response mapping, and surface-based multivoxel pattern analysis, we demonstrated that VTC in blind individuals shows robust discriminatory responses elicited by the four categories and that these patterns of activity in blind subjects could successfully predict the visual categories in sighted controls. These findings were confirmed in a subset of blind participants born without eyes and thus deprived from all light perception since conception. The sounds also could be decoded in primary visual and primary auditory cortex, but these regions did not sustain generalization across modalities. Surprisingly, although not as strong as visual responses, selectivity for auditory stimulation in visual cortex was stronger in blind individuals than in controls. The opposite was observed in primary auditory cortex. Overall, we demonstrated a striking similarity in the cortical response layout of VTC in blind individuals and sighted controls, demonstrating that the overall category-selective map in extrastriate cortex develops independently from visual experience.

scholarly journals Functional specialization for auditory-spatial processing in the occipital cortex of congenitally blind humans

2011 ◽  
Vol 108 (11) ◽  
pp. 4435-4440 ◽  
Author(s):  
O. Collignon ◽  
G. Vandewalle ◽  
P. Voss ◽  
G. Albouy ◽  
G. Charbonneau ◽  
...  
Keyword(s):  
Occipital Cortex ◽  
Spatial Processing ◽  
Functional Specialization ◽  
Congenitally Blind ◽  
Blind Humans

scholarly journals Adaptive Changes in Early and Late Blind: A fMRI Study of Braille Reading

2002 ◽  
Vol 87 (1) ◽  
pp. 589-607 ◽  
Author(s):  
H. Burton ◽  
A. Z. Snyder ◽  
T. E. Conturo ◽  
E. Akbudak ◽  
J. M. Ollinger ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Language Processing ◽  
Tactile Stimulation ◽  
Primary Motor Cortex ◽  
Late Onset ◽  
Inferior Frontal Gyrus ◽  
Temporal Cortex ◽  
Somatosensory System ◽  
Occipital Cortex ◽  
Blind Individuals

Braille reading depends on remarkable adaptations that connect the somatosensory system to language. We hypothesized that the pattern of cortical activations in blind individuals reading Braille would reflect these adaptations. Activations in visual (occipital-temporal), frontal-language, and somatosensory cortex in blind individuals reading Braille were examined for evidence of differences relative to previously reported studies of sighted subjects reading print or receiving tactile stimulation. Nine congenitally blind and seven late-onset blind subjects were studied with fMRI as they covertly performed verb generation in response to reading Braille embossed nouns. The control task was reading the nonlexical Braille string “######”. This study emphasized image analysis in individual subjects rather than pooled data. Group differences were examined by comparing magnitudes and spatial extent of activated regions first determined to be significant using the general linear model. The major adaptive change was robust activation of visual cortex despite the complete absence of vision in all subjects. This included foci in peri-calcarine, lingual, cuneus and fusiform cortex, and in the lateral and superior occipital gyri encompassing primary (V1), secondary (V2), and higher tier (VP, V4v, LO and possibly V3A) visual areas previously identified in sighted subjects. Subjects who never had vision differed from late blind subjects in showing even greater activity in occipital-temporal cortex, provisionally corresponding to V5/MT and V8. In addition, the early blind had stronger activation of occipital cortex located contralateral to the hand used for reading Braille. Responses in frontal and parietal cortex were nearly identical in both subject groups. There was no evidence of modifications in frontal cortex language areas (inferior frontal gyrus and dorsolateral prefrontal cortex). Surprisingly, there was also no evidence of an adaptive expansion of the somatosensory or primary motor cortex dedicated to the Braille reading finger(s). Lack of evidence for an expected enlargement of the somatosensory representation may have resulted from balanced tactile stimulation and gross motor demands during Braille reading of nouns and the control fields. Extensive engagement of visual cortex without vision is discussed in reference to the special demands of Braille reading. It is argued that these responses may represent critical language processing mechanisms normally present in visual cortex.

Modality Dependent Cross-Modal Functional Reorganization Following Congenital Visual Deprivation within Occipital Areas: A Meta-Analysis of Tactile and Auditory Studies

2014 ◽  
Vol 27 (3-4) ◽  
pp. 247-262 ◽  
Author(s):  
Emiliano Ricciardi ◽  
Leonardo Tozzi ◽  
Andrea Leo ◽  
Pietro Pietrini
Keyword(s):  
Visual Information ◽  
Meta Analysis ◽  
Sensory Modality ◽  
Temporal Cortex ◽  
Sensory Information ◽  
Occipital Cortex ◽  
Inferior Temporal Cortex ◽  
Functional Studies ◽  
Superior Parietal Cortex ◽  
Blind Individuals

Cross-modal responses in occipital areas appear to be essential for sensory processing in visually deprived subjects. However, it is yet unclear whether this functional recruitment might be dependent on the sensory channel conveying the information. In order to characterize brain areas showing task-independent, but sensory specific, cross-modal responses in blind individuals, we pooled together distinct brain functional studies in a single based meta-analysis according only to the modality conveying experimental stimuli (auditory or tactile). Our approach revealed a specific functional cortical segregation according to the sensory modality conveying the non-visual information, irrespectively from the cognitive features of the tasks. In particular, dorsal and posterior subregions of occipital and superior parietal cortex showed a higher cross-modal recruitment across tactile tasks in blind as compared to sighted individuals. On the other hand, auditory stimuli activated more medial and ventral clusters within early visual areas, the lingual and inferior temporal cortex. These findings suggest a modality-specific functional modification of cross-modal responses within different portions of the occipital cortex of blind individuals. Cross-modal recruitment can thus be specifically influenced by the intrinsic features of sensory information.

scholarly journals A thalamocortical pathway for fast rerouting of tactile information to occipital cortex in congenital blindness

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Franziska Müller ◽  
Guiomar Niso ◽  
Soheila Samiee ◽  
Maurice Ptito ◽  
Sylvain Baillet ◽  
...  
Keyword(s):  
Animal Studies ◽  
Tactile Stimulation ◽  
Occipital Cortex ◽  
Alpha Band ◽  
Response Latencies ◽  
Tactile Information ◽  
Congenitally Blind ◽  
Blind Individuals ◽  
Subcortical Pathway ◽  
Blind Humans

AbstractIn congenitally blind individuals, the occipital cortex responds to various nonvisual inputs. Some animal studies raise the possibility that a subcortical pathway allows fast re-routing of tactile information to the occipital cortex, but this has not been shown in humans. Here we show using magnetoencephalography (MEG) that tactile stimulation produces occipital cortex activations, starting as early as 35 ms in congenitally blind individuals, but not in blindfolded sighted controls. Given our measured thalamic response latencies of 20 ms and a mean estimated lateral geniculate nucleus to primary visual cortex transfer time of 15 ms, we claim that this early occipital response is mediated by a direct thalamo-cortical pathway. We also observed stronger directed connectivity in the alpha band range from posterior thalamus to occipital cortex in congenitally blind participants. Our results strongly suggest the contribution of a fast thalamo-cortical pathway in the cross-modal activation of the occipital cortex in congenitally blind humans.

scholarly journals Neural Correlates of Phonetic Adaptation as Induced by Lexical and Audiovisual Context

2020 ◽  
Vol 32 (11) ◽  
pp. 2145-2158 ◽  
Author(s):  
Shruti Ullas ◽  
Lars Hausfeld ◽  
Anne Cutler ◽  
Frank Eisner ◽  
Elia Formisano
Keyword(s):  
Perceptual Learning ◽  
Visual Information ◽  
Contextual Information ◽  
Temporal Cortex ◽  
Occipital Cortex ◽  
Activity Levels ◽  
Response Patterns ◽  
Brain Response ◽  
Activation Patterns ◽  
Brain Responses

When speech perception is difficult, one way listeners adjust is by reconfiguring phoneme category boundaries, drawing on contextual information. Both lexical knowledge and lipreading cues are used in this way, but it remains unknown whether these two differing forms of perceptual learning are similar at a neural level. This study compared phoneme boundary adjustments driven by lexical or audiovisual cues, using ultra-high-field 7-T fMRI. During imaging, participants heard exposure stimuli and test stimuli. Exposure stimuli for lexical retuning were audio recordings of words, and those for audiovisual recalibration were audio–video recordings of lip movements during utterances of pseudowords. Test stimuli were ambiguous phonetic strings presented without context, and listeners reported what phoneme they heard. Reports reflected phoneme biases in preceding exposure blocks (e.g., more reported /p/ after /p/-biased exposure). Analysis of corresponding brain responses indicated that both forms of cue use were associated with a network of activity across the temporal cortex, plus parietal, insula, and motor areas. Audiovisual recalibration also elicited significant occipital cortex activity despite the lack of visual stimuli. Activity levels in several ROIs also covaried with strength of audiovisual recalibration, with greater activity accompanying larger recalibration shifts. Similar activation patterns appeared for lexical retuning, but here, no significant ROIs were identified. Audiovisual and lexical forms of perceptual learning thus induce largely similar brain response patterns. However, audiovisual recalibration involves additional visual cortex contributions, suggesting that previously acquired visual information (on lip movements) is retrieved and deployed to disambiguate auditory perception.

scholarly journals Recruitment of occipital cortex by arithmetic processing follows computational bias in early blind

2018 ◽  
Author(s):  
Virginie Crollen ◽  
Latifa Lazzouni ◽  
Antoine Bellemare ◽  
Mohamed Rezk ◽  
Franco Lepore ◽  
...  
Keyword(s):  
Brain Activity ◽  
Occipital Cortex ◽  
Spatial Processing ◽  
Functional Flexibility ◽  
Multiplication Task ◽  
The Right ◽  
High Level ◽  
Blind Individuals ◽  
The Brain

AbstractArithmetic reasoning activates the occipital cortex of early blind people (EB). This activation of visual areas may reflect functional flexibility or the intrinsic computational role of specific occipital regions. We contrasted these competing hypotheses by characterizing the brain activity of EB and sighted participants while performing subtraction, multiplication and a control verbal task. In both groups, subtraction selectively activated a bilateral dorsal network commonly activated during spatial processing. Multiplication triggered more activity in temporal regions thought to participate in memory retrieval. No between-group difference was observed for the multiplication task whereas subtraction induced enhanced activity in the right dorsal occipital cortex of the blind individuals only. As this area overlaps and exhibits increased functional connectivity with regions showing selective tuning to auditory spatial processing, our results suggest that the recruitment of occipital regions during high-level cognition in the blind actually relates to the intrinsic computational role of the reorganized regions.

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