51
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Tomasello R, Wennekers T, Garagnani M, Pulvermüller F. Visual cortex recruitment during language processing in blind individuals is explained by Hebbian learning. Sci Rep 2019; 9:3579. [PMID: 30837569 PMCID: PMC6400975 DOI: 10.1038/s41598-019-39864-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 02/04/2019] [Indexed: 12/29/2022] Open
Abstract
In blind people, the visual cortex takes on higher cognitive functions, including language. Why this functional reorganisation mechanistically emerges at the neuronal circuit level is still unclear. Here, we use a biologically constrained network model implementing features of anatomical structure, neurophysiological function and connectivity of fronto-temporal-occipital areas to simulate word-meaning acquisition in visually deprived and undeprived brains. We observed that, only under visual deprivation, distributed word-related neural circuits 'grew into' the deprived visual areas, which therefore adopted a linguistic-semantic role. Three factors are crucial for explaining this deprivation-related growth: changes in the network's activity balance brought about by the absence of uncorrelated sensory input, the connectivity structure of the network, and Hebbian correlation learning. In addition, the blind model revealed long-lasting spiking neural activity compared to the sighted model during word recognition, which is a neural correlate of enhanced verbal working memory. The present neurocomputational model offers a neurobiological account for neural changes following sensory deprivation, thus closing the gap between cellular-level mechanisms, system-level linguistic and semantic function.
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Affiliation(s)
- Rosario Tomasello
- Brain Language Laboratory, Department of Philosophy and Humanities, WE4 Freie Universität Berlin, Habelschwerdter Allee 45, 14195, Berlin, Germany.
- Berlin School of Mind and Brain, Humboldt Universität zu Berlin, Luisenstraße 56, 10117, Berlin, Germany.
| | - Thomas Wennekers
- Centre for Robotics and Neural Systems (CRNS), University of Plymouth, A311 Portland Square Building, PL4 8AA, Plymouth, Devon, United Kingdom
| | - Max Garagnani
- Brain Language Laboratory, Department of Philosophy and Humanities, WE4 Freie Universität Berlin, Habelschwerdter Allee 45, 14195, Berlin, Germany
- Department of Computing, Goldsmiths, University of London, SE14 6NW, London, United Kingdom
| | - Friedemann Pulvermüller
- Brain Language Laboratory, Department of Philosophy and Humanities, WE4 Freie Universität Berlin, Habelschwerdter Allee 45, 14195, Berlin, Germany
- Berlin School of Mind and Brain, Humboldt Universität zu Berlin, Luisenstraße 56, 10117, Berlin, Germany
- Einstein Center for Neurosciences, Charitéplatz 1, 10117, Berlin, Germany
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52
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Duc NT, Lee B. Microstate functional connectivity in EEG cognitive tasks revealed by a multivariate Gaussian hidden Markov model with phase locking value. J Neural Eng 2019; 16:026033. [DOI: 10.1088/1741-2552/ab0169] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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53
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Stronger responses in the visual cortex of sighted compared to blind individuals during auditory space representation. Sci Rep 2019; 9:1935. [PMID: 30760758 PMCID: PMC6374481 DOI: 10.1038/s41598-018-37821-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 12/11/2018] [Indexed: 01/02/2023] Open
Abstract
It has been previously shown that the interaction between vision and audition involves early sensory cortices. However, the functional role of these interactions and their modulation due to sensory impairment is not yet understood. To shed light on the impact of vision on auditory spatial processing, we recorded ERPs and collected psychophysical responses during space and time bisection tasks in sighted and blind participants. They listened to three consecutive sounds and judged whether the second sound was either spatially or temporally further from the first or the third sound. We demonstrate that spatial metric representation of sounds elicits an early response of the visual cortex (P70) which is different between sighted and visually deprived individuals. Indeed, only in sighted and not in blind people P70 is strongly selective for the spatial position of sounds, mimicking many aspects of the visual-evoked C1. These results suggest that early auditory processing associated with the construction of spatial maps is mediated by visual experience. The lack of vision might impair the projection of multi-sensory maps on the retinotopic maps used by the visual cortex.
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54
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Wesselink DB, van den Heiligenberg FM, Ejaz N, Dempsey-Jones H, Cardinali L, Tarall-Jozwiak A, Diedrichsen J, Makin TR. Obtaining and maintaining cortical hand representation as evidenced from acquired and congenital handlessness. eLife 2019; 8:37227. [PMID: 30717824 PMCID: PMC6363469 DOI: 10.7554/elife.37227] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 01/12/2019] [Indexed: 12/26/2022] Open
Abstract
A key question in neuroscience is how cortical organisation relates to experience. Previously we showed that amputees experiencing highly vivid phantom sensations maintain cortical representation of their missing hand (Kikkert et al., 2016). Here, we examined the role of sensory hand experience on persistent hand representation by studying individuals with acquired and congenital hand loss. We used representational similarity analysis in primary somatosensory and motor cortex during missing and intact hand movements. We found that key aspects of acquired amputees’ missing hand representation persisted, despite varying vividness of phantom sensations. In contrast, missing hand representation of congenital one-handers, who do not experience phantom sensations, was significantly reduced. Across acquired amputees, individuals’ reported motor control over their phantom hand positively correlated with the extent to which their somatosensory hand representation was normally organised. We conclude that once cortical organisation is formed, it is remarkably persistent, despite long-term attenuation of peripheral signals.
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Affiliation(s)
- Daan B Wesselink
- Institute of Cognitive Neuroscience, University College London, London, United Kingdom.,Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, United Kingdom
| | - Fiona Mz van den Heiligenberg
- Institute of Cognitive Neuroscience, University College London, London, United Kingdom.,Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, United Kingdom
| | - Naveed Ejaz
- Brain and Mind Institute, University of Western Ontario, London, Canada.,Department of Computer Science, University of Western Ontario, London, Canada
| | - Harriet Dempsey-Jones
- Institute of Cognitive Neuroscience, University College London, London, United Kingdom.,Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, United Kingdom
| | - Lucilla Cardinali
- Brain and Mind Institute, University of Western Ontario, London, Canada.,Unit for Visually Impaired People, Istituto Italiano di Tecnologia, Genoa, Italy
| | | | - Jörn Diedrichsen
- Brain and Mind Institute, University of Western Ontario, London, Canada.,Department of Computer Science, University of Western Ontario, London, Canada
| | - Tamar R Makin
- Institute of Cognitive Neuroscience, University College London, London, United Kingdom.,Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, United Kingdom.,Wellcome Centre for Human Neuroimaging, University College London, London, United Kingdom
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55
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Schaefer A, Kong R, Gordon EM, Laumann TO, Zuo XN, Holmes AJ, Eickhoff SB, Yeo BTT. Local-Global Parcellation of the Human Cerebral Cortex from Intrinsic Functional Connectivity MRI. Cereb Cortex 2018; 28:3095-3114. [PMID: 28981612 PMCID: PMC6095216 DOI: 10.1093/cercor/bhx179] [Citation(s) in RCA: 1404] [Impact Index Per Article: 234.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2016] [Revised: 04/26/2017] [Accepted: 06/23/2017] [Indexed: 12/17/2022] Open
Abstract
A central goal in systems neuroscience is the parcellation of the cerebral cortex into discrete neurobiological "atoms". Resting-state functional magnetic resonance imaging (rs-fMRI) offers the possibility of in vivo human cortical parcellation. Almost all previous parcellations relied on 1 of 2 approaches. The local gradient approach detects abrupt transitions in functional connectivity patterns. These transitions potentially reflect cortical areal boundaries defined by histology or visuotopic fMRI. By contrast, the global similarity approach clusters similar functional connectivity patterns regardless of spatial proximity, resulting in parcels with homogeneous (similar) rs-fMRI signals. Here, we propose a gradient-weighted Markov Random Field (gwMRF) model integrating local gradient and global similarity approaches. Using task-fMRI and rs-fMRI across diverse acquisition protocols, we found gwMRF parcellations to be more homogeneous than 4 previously published parcellations. Furthermore, gwMRF parcellations agreed with the boundaries of certain cortical areas defined using histology and visuotopic fMRI. Some parcels captured subareal (somatotopic and visuotopic) features that likely reflect distinct computational units within known cortical areas. These results suggest that gwMRF parcellations reveal neurobiologically meaningful features of brain organization and are potentially useful for future applications requiring dimensionality reduction of voxel-wise fMRI data. Multiresolution parcellations generated from 1489 participants are publicly available (https://github.com/ThomasYeoLab/CBIG/tree/master/stable_projects/brain_parcellation/Schaefer2018_LocalGlobal).
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Affiliation(s)
- Alexander Schaefer
- Department of Electrical and Computer Engineering, ASTAR-NUS Clinical Imaging Research Centre, Singapore Institute for Neurotechnology and Memory Networks Program, National University of Singapore, Singapore
| | - Ru Kong
- Department of Electrical and Computer Engineering, ASTAR-NUS Clinical Imaging Research Centre, Singapore Institute for Neurotechnology and Memory Networks Program, National University of Singapore, Singapore
| | - Evan M Gordon
- VISN 17 Center of Excellence for Research on Returning War Veterans, Waco, TX, USA
| | - Timothy O Laumann
- Department of Neurology, Washington University in St. Louis, St. Louis, MO, USA
| | - Xi-Nian Zuo
- CAS Key Laboratory of Behavioral Sciences, Institute of Psychology, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | | | - Simon B Eickhoff
- Institute for Systems Neuroscience, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
- Institute of Neuroscience and Medicine, Brain and Behaviour (INM-7), Research Center Jülich, Jülich, Germany
| | - B T Thomas Yeo
- Department of Electrical and Computer Engineering, ASTAR-NUS Clinical Imaging Research Centre, Singapore Institute for Neurotechnology and Memory Networks Program, National University of Singapore, Singapore
- Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA
- Centre for Cognitive Neuroscience, Duke-NUS Medical School, Singapore, Singapore
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56
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Li Q, Song M, Xu J, Qin W, Yu C, Jiang T. Cortical thickness development of human primary visual cortex related to the age of blindness onset. Brain Imaging Behav 2018; 11:1029-1036. [PMID: 27468855 DOI: 10.1007/s11682-016-9576-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Blindness primarily induces structural alteration in the primary visual cortex (V1). Some studies have found that the early blind subjects had a thicker V1 compared to sighted controls, whereas late blind subjects showed no significant differences in the V1. This implies that the age of blindness onset may exert significant effects on the development of cortical thickness of the V1. However, no previous research used a trajectory of the age of blindness onset-related changes to investigate these effects. Here we explored this issue by mapping the cortical thickness trajectory of the V1 against the age of blindness onset using data from 99 blind individuals whose age of blindness onset ranged from birth to 34 years. We found that the cortical thickness of the V1 could be fitted well with a quadratic curve in both the left (F = 11.59, P = 3 × 10-5) and right hemispheres (F = 6.54, P = 2 × 10-3). Specifically, the cortical thickness of the V1 thinned rapidly during childhood and adolescence and did not change significantly thereafter. This trend was not observed in the primary auditory cortex (A1), primary motor cortex (M1), or primary somatosensory cortex (S1). These results provide evidence that an onset of blindness before adulthood significantly affects the cortical thickness of the V1 and suggest a critical period for cortical development of the human V1.
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Affiliation(s)
- Qiaojun Li
- Brainnetome Center, Institute of Automation, Chinese Academy of Sciences, Beijing, People's Republic of China.,National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China
| | - Ming Song
- Brainnetome Center, Institute of Automation, Chinese Academy of Sciences, Beijing, People's Republic of China.,National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China
| | - Jiayuan Xu
- Department of Radiology, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Wen Qin
- Department of Radiology, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Chunshui Yu
- Department of Radiology, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Tianzi Jiang
- Brainnetome Center, Institute of Automation, Chinese Academy of Sciences, Beijing, People's Republic of China. .,National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China. .,CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Automation, Chinese Academy of Sciences, Beijing, People's Republic of China. .,The Queensland Brain Institute, University of Queensland, QLD, Brisbane, Australia.
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57
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Abstract
Inferior temporal cortex (IT) is a key part of the ventral visual pathway implicated in object, face, and scene perception. But how does IT work? Here, I describe an organizational scheme that marries form and function and provides a framework for future research. The scheme consists of a series of stages arranged along the posterior-anterior axis of IT, defined by anatomical connections and functional responses. Each stage comprises a complement of subregions that have a systematic spatial relationship. The organization of each stage is governed by an eccentricity template, and corresponding eccentricity representations across stages are interconnected. Foveal representations take on a role in high-acuity object vision (including face recognition); intermediate representations compute other aspects of object vision such as behavioral valence (using color and surface cues); and peripheral representations encode information about scenes. This multistage, parallel-processing model invokes an innately determined organization refined by visual experience that is consistent with principles of cortical development. The model is also consistent with principles of evolution, which suggest that visual cortex expanded through replication of retinotopic areas. Finally, the model predicts that the most extensively studied network within IT-the face patches-is not unique but rather one manifestation of a canonical set of operations that reveal general principles of how IT works.
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Affiliation(s)
- Bevil R Conway
- Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland 28092, USA; .,National Institutes of Mental Health, National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland 28092, USA
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58
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Nishiguchi KM, Fujita K, Tokashiki N, Komamura H, Takemoto-Kimura S, Okuno H, Bito H, Nakazawa T. Retained Plasticity and Substantial Recovery of Rod-Mediated Visual Acuity at the Visual Cortex in Blind Adult Mice with Retinal Dystrophy. Mol Ther 2018; 26:2397-2406. [PMID: 30064895 DOI: 10.1016/j.ymthe.2018.07.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 07/08/2018] [Accepted: 07/12/2018] [Indexed: 12/01/2022] Open
Abstract
In patients born blind with retinal dystrophies, understanding the critical periods of cortical plasticity is important for successful visual restoration. In this study, we sought to model childhood blindness and investigate the plasticity of visual pathways. To this end, we generated double-mutant (Pde6ccpfl1/cpfl1Gnat1IRD2/IRD2) mice with absent rod and cone photoreceptor function, and we evaluated their response for restoring rod (GNAT1) function through gene therapy. Despite the limited effectiveness of gene therapy in restoring visual acuity in patients with retinal dystrophy, visual acuity was, unexpectedly, successfully restored in the mice at the level of the primary visual cortex in this study. This success in visual restoration, defined by changes in the quantified optokinetic response and pattern visually evoked potential, was achieved regardless of the age at treatment (up to 16 months). In the contralateral visual cortex, cortical plasticity, tagged with light-triggered transcription of Arc, was also restored after the treatment in blind mice carrying an Arc promoter-driven reporter gene, dVenus. Our results demonstrate the remarkable plasticity of visual circuits for one of the two photoreceptor mechanisms in older as well as younger mice with congenital blindness due to retinal dystrophies.
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Affiliation(s)
- Koji M Nishiguchi
- Department of Advanced Ophthalmic Medicine, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan; Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan.
| | - Kosuke Fujita
- Department of Retinal Disease Control, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan
| | - Naoyuki Tokashiki
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan
| | - Hiroshi Komamura
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan
| | - Sayaka Takemoto-Kimura
- Department of Neuroscience I, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Japan; PRESTO-Japan Science and Technology Agency, Chiyoda-ku, Tokyo, Japan
| | - Hiroyuki Okuno
- Medical Innovation Center, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Haruhiko Bito
- Department of Neurochemistry, Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan
| | - Toru Nakazawa
- Department of Advanced Ophthalmic Medicine, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan; Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan; Department of Retinal Disease Control, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan
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59
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Plasticity based on compensatory effector use in the association but not primary sensorimotor cortex of people born without hands. Proc Natl Acad Sci U S A 2018; 115:7801-7806. [PMID: 29997174 PMCID: PMC6065047 DOI: 10.1073/pnas.1803926115] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
What forces direct brain organization and its plasticity? When brain regions are deprived of their input, which regions reorganize based on compensation for the disability and experience, and which regions show topographically constrained plasticity? People born without hands activate their primary sensorimotor hand region while moving body parts used to compensate for this disability (e.g., their feet). This was taken to suggest a neural organization based on functions, such as performing manual-like dexterous actions, rather than on body parts, in primary sensorimotor cortex. We tested the selectivity for the compensatory body parts in the primary and association sensorimotor cortex of people born without hands (dysplasic individuals). Despite clear compensatory foot use, the primary sensorimotor hand area in the dysplasic subjects showed preference for adjacent body parts that are not compensatorily used as effectors. This suggests that function-based organization, proposed for congenital blindness and deafness, does not apply to the primary sensorimotor cortex deprivation in dysplasia. These findings stress the roles of neuroanatomical constraints like topographical proximity and connectivity in determining the functional development of primary cortex even in extreme, congenital deprivation. In contrast, increased and selective foot movement preference was found in dysplasics' association cortex in the inferior parietal lobule. This suggests that the typical motor selectivity of this region for manual actions may correspond to high-level action representations that are effector-invariant. These findings reveal limitations to compensatory plasticity and experience in modifying brain organization of early topographical cortex compared with association cortices driven by function-based organization.
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60
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Abstract
Early blindness causes fundamental alterations of neural function across more than 25% of cortex-changes that span the gamut from metabolism to behavior and collectively represent one of the most dramatic examples of plasticity in the human brain. The goal of this review is to describe how the remarkable behavioral and neuroanatomical compensations demonstrated by blind individuals provide insights into the extent, mechanisms, and limits of human brain plasticity.
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Affiliation(s)
- Ione Fine
- Department of Psychology, University of Washington, Seattle, Washington 98195, USA;
| | - Ji-Min Park
- Department of Psychology, University of Washington, Seattle, Washington 98195, USA;
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61
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Voss P. Brain (re)organization following visual loss. WILEY INTERDISCIPLINARY REVIEWS. COGNITIVE SCIENCE 2018; 10:e1468. [PMID: 29878533 DOI: 10.1002/wcs.1468] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 05/04/2018] [Accepted: 05/07/2018] [Indexed: 11/10/2022]
Abstract
The study of the neural consequences of sensory loss provides a unique window into the brain's functional and organizational principles. Although the blind visual cortex has been implicated in the cross-modal processing of nonvisual inputs for quite some time, recent research has shown that certain cortical organizational principles are preserved even in the case of complete sensory loss. Furthermore, a growing body of work has shown that markers of neuroplasticity extend to neuroanatomical metrics that include cortical thickness and myelinization. Although our understanding of the mechanisms that underlie sensory deprivation-driven cross-modal plasticity is improving, several critical questions remain unanswered. The specific pathways that underlie the rerouting of nonvisual information, for instance, have not been fully elucidated. The fact that important cross-modal recruitment occurs following transient deprivation in sighted individuals suggests that significant rewiring following blindness may not be required. Furthermore, there are marked individual differences regarding the magnitude and functional relevance of the cross-modal reorganization. It is also not clear to what extent precise environmental factors may play a role in establishing the degree of reorganization across individuals, as opposed to factors that might specifically relate to the cause or the nature of the visual loss. In sum, although many unresolved questions remain, sensory deprivation continues to be an excellent model for studying the plastic nature of the brain. This article is categorized under: Psychology > Brain Function and Dysfunction Psychology > Perception and Psychophysics Neuroscience > Plasticity.
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Affiliation(s)
- Patrice Voss
- Montreal Neurological Institute, McGill University, Montreal, Canada
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62
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Wilf M, Strappini F, Golan T, Hahamy A, Harel M, Malach R. Spontaneously Emerging Patterns in Human Visual Cortex Reflect Responses to Naturalistic Sensory Stimuli. Cereb Cortex 2018; 27:750-763. [PMID: 26574501 DOI: 10.1093/cercor/bhv275] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
In the absence of stimulus or task, the cortex spontaneously generates rich and consistent functional connectivity patterns (termed resting state networks) which are evident even within individual cortical areas. We and others have previously hypothesized that habitual cortical network activations during daily life contribute to the shaping of these connectivity patterns. Here we tested this hypothesis by comparing, using blood oxygen level-dependent-functional magnetic resonance imaging, the connectivity patterns that spontaneously emerge during rest in retinotopic visual areas to the patterns generated by naturalistic visual stimuli (repeated movie segments). These were then compared with connectivity patterns produced by more standard retinotopic mapping stimuli (polar and eccentricity mapping). Our results reveal that the movie-driven patterns were significantly more similar to the spontaneously emerging patterns, compared with the connectivity patterns of either eccentricity or polar mapping stimuli. Intentional visual imagery of naturalistic stimuli was unlikely to underlie these results, since they were duplicated when participants were engaged in an auditory task. Our results suggest that the connectivity patterns that appear during rest better reflect naturalistic activations rather than controlled, artificially designed stimuli. The results are compatible with the hypothesis that the spontaneous connectivity patterns in human retinotopic areas reflect the statistics of cortical coactivations during natural vision.
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Affiliation(s)
- Meytal Wilf
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Francesca Strappini
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Tal Golan
- The Edmund and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Avital Hahamy
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Michal Harel
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Rafael Malach
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
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63
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Van Ackeren MJ, Barbero FM, Mattioni S, Bottini R, Collignon O. Neuronal populations in the occipital cortex of the blind synchronize to the temporal dynamics of speech. eLife 2018; 7:e31640. [PMID: 29338838 PMCID: PMC5790372 DOI: 10.7554/elife.31640] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 01/16/2018] [Indexed: 11/13/2022] Open
Abstract
The occipital cortex of early blind individuals (EB) activates during speech processing, challenging the notion of a hard-wired neurobiology of language. But, at what stage of speech processing do occipital regions participate in EB? Here we demonstrate that parieto-occipital regions in EB enhance their synchronization to acoustic fluctuations in human speech in the theta-range (corresponding to syllabic rate), irrespective of speech intelligibility. Crucially, enhanced synchronization to the intelligibility of speech was selectively observed in primary visual cortex in EB, suggesting that this region is at the interface between speech perception and comprehension. Moreover, EB showed overall enhanced functional connectivity between temporal and occipital cortices that are sensitive to speech intelligibility and altered directionality when compared to the sighted group. These findings suggest that the occipital cortex of the blind adopts an architecture that allows the tracking of speech material, and therefore does not fully abstract from the reorganized sensory inputs it receives.
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Affiliation(s)
| | - Francesca M Barbero
- Institute of research in PsychologyUniversity of LouvainLouvainBelgium
- Institute of NeuroscienceUniversity of LouvainLouvainBelgium
| | | | - Roberto Bottini
- Center for Mind/Brain StudiesUniversity of TrentoTrentoItaly
| | - Olivier Collignon
- Center for Mind/Brain StudiesUniversity of TrentoTrentoItaly
- Institute of research in PsychologyUniversity of LouvainLouvainBelgium
- Institute of NeuroscienceUniversity of LouvainLouvainBelgium
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64
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Abstract
Much remains to be understood about visual system malfunction following injury. The resulting deficits range from dense, visual field scotomas to mild dysfunction of visual perception. Despite the predictive value of anatomical localization studies, much patient-to-patient variability remains regarding (a) perceptual abilities following injury and (b) the capacity of individual patients for visual rehabilitation. Visual field perimetry is used to characterize the visual field deficits that result from visual system injury. However, standard perimetry mapping does not always precisely correspond to underlying anatomical or functional deficits. Functional magnetic resonance imaging can be used to probe the function of surviving visual circuits, allowing us to classify better how the pattern of injury relates to residual visual perception. Identifying pathways that are potentially modifiable by training may guide the development of improved strategies for visual rehabilitation. This review discusses primary visual cortex lesions, which cause dense contralateral scotomas.
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Affiliation(s)
- Stelios M Smirnakis
- Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts 02115.,Department of Neurology, Jamaica Plain Campus, Veterans Administration Boston Healthcare System, Boston, Massachusetts 02130.,Harvard Medical School, Boston, Massachusetts 02115;
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65
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Ursino M, Crisafulli A, di Pellegrino G, Magosso E, Cuppini C. Development of a Bayesian Estimator for Audio-Visual Integration: A Neurocomputational Study. Front Comput Neurosci 2017; 11:89. [PMID: 29046631 PMCID: PMC5633019 DOI: 10.3389/fncom.2017.00089] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 09/20/2017] [Indexed: 11/17/2022] Open
Abstract
The brain integrates information from different sensory modalities to generate a coherent and accurate percept of external events. Several experimental studies suggest that this integration follows the principle of Bayesian estimate. However, the neural mechanisms responsible for this behavior, and its development in a multisensory environment, are still insufficiently understood. We recently presented a neural network model of audio-visual integration (Neural Computation, 2017) to investigate how a Bayesian estimator can spontaneously develop from the statistics of external stimuli. Model assumes the presence of two unimodal areas (auditory and visual) topologically organized. Neurons in each area receive an input from the external environment, computed as the inner product of the sensory-specific stimulus and the receptive field synapses, and a cross-modal input from neurons of the other modality. Based on sensory experience, synapses were trained via Hebbian potentiation and a decay term. Aim of this work is to improve the previous model, including a more realistic distribution of visual stimuli: visual stimuli have a higher spatial accuracy at the central azimuthal coordinate and a lower accuracy at the periphery. Moreover, their prior probability is higher at the center, and decreases toward the periphery. Simulations show that, after training, the receptive fields of visual and auditory neurons shrink to reproduce the accuracy of the input (both at the center and at the periphery in the visual case), thus realizing the likelihood estimate of unimodal spatial position. Moreover, the preferred positions of visual neurons contract toward the center, thus encoding the prior probability of the visual input. Finally, a prior probability of the co-occurrence of audio-visual stimuli is encoded in the cross-modal synapses. The model is able to simulate the main properties of a Bayesian estimator and to reproduce behavioral data in all conditions examined. In particular, in unisensory conditions the visual estimates exhibit a bias toward the fovea, which increases with the level of noise. In cross modal conditions, the SD of the estimates decreases when using congruent audio-visual stimuli, and a ventriloquism effect becomes evident in case of spatially disparate stimuli. Moreover, the ventriloquism decreases with the eccentricity.
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Affiliation(s)
- Mauro Ursino
- Department of Electrical, Electronic and Information Engineering, University of Bologna, Bologna, Italy
| | | | | | - Elisa Magosso
- Department of Electrical, Electronic and Information Engineering, University of Bologna, Bologna, Italy
| | - Cristiano Cuppini
- Department of Electrical, Electronic and Information Engineering, University of Bologna, Bologna, Italy
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66
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Butler BE, de la Rua A, Ward-Able T, Lomber SG. Cortical and thalamic connectivity to the second auditory cortex of the cat is resilient to the onset of deafness. Brain Struct Funct 2017; 223:819-835. [PMID: 28940055 DOI: 10.1007/s00429-017-1523-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 09/04/2017] [Indexed: 10/18/2022]
Abstract
It has been well established that following sensory loss, cortical areas that would normally be involved in perceiving stimuli in the absent modality are recruited to subserve the remaining senses. Despite this compensatory functional reorganization, there is little evidence to date for any substantial change in the patterns of anatomical connectivity between sensory cortices. However, while many auditory areas are contracted in the deaf, the second auditory cortex (A2) of the cat undergoes a volumetric expansion following hearing loss, suggesting this cortical area may demonstrate a region-specific pattern of structural reorganization. To address this hypothesis, and to complement existing literature on connectivity within auditory cortex, we injected a retrograde neuronal tracer across the breadth and cortical thickness of A2 to provide the first comprehensive quantification of projections from cortical and thalamic auditory and non-auditory regions to the second auditory cortex, and to determine how these patterns are affected by the onset of deafness. Neural projections arising from auditory, visual, somatomotor, and limbic cortices, as well as thalamic nuclei, were compared across normal hearing, early-deaf, and late-deaf animals. The results demonstrate that, despite previously identified changes in A2 volume, the pattern of projections into this cortical region are unaffected by the onset of hearing loss. These results fail to support the idea that crossmodal plasticity reflects changes in the pattern of projections between cortical regions and provides evidence that the pattern of connectivity that supports normal hearing is retained in the deaf brain.
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Affiliation(s)
- Blake E Butler
- Cerebral Systems Laboratory, University of Western Ontario, London, ON, N6A 5C2, Canada. .,Department of Psychology, University of Western Ontario, London, ON, N6A 5C2, Canada. .,Brain and Mind Institute, University of Western Ontario, London, ON, N6A 5B7, Canada. .,National Centre for Audiology, University of Western Ontario, London, ON, N6G 1H1, Canada.
| | - Alexandra de la Rua
- Cerebral Systems Laboratory, University of Western Ontario, London, ON, N6A 5C2, Canada.,Neuroscience Undergraduate Program, University of Western Ontario, London, ON, N6A 3K7, Canada
| | - Taylor Ward-Able
- Cerebral Systems Laboratory, University of Western Ontario, London, ON, N6A 5C2, Canada.,Neuroscience Undergraduate Program, University of Western Ontario, London, ON, N6A 3K7, Canada
| | - Stephen G Lomber
- Cerebral Systems Laboratory, University of Western Ontario, London, ON, N6A 5C2, Canada.,Department of Psychology, University of Western Ontario, London, ON, N6A 5C2, Canada.,Brain and Mind Institute, University of Western Ontario, London, ON, N6A 5B7, Canada.,National Centre for Audiology, University of Western Ontario, London, ON, N6G 1H1, Canada.,Department of Physiology and Pharmacology, University of Western Ontario, London, ON, N6A 5C1, Canada
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67
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Le Meur G, Lebranchu P, Billaud F, Adjali O, Schmitt S, Bézieau S, Péréon Y, Valabregue R, Ivan C, Darmon C, Moullier P, Rolling F, Weber M. Safety and Long-Term Efficacy of AAV4 Gene Therapy in Patients with RPE65 Leber Congenital Amaurosis. Mol Ther 2017; 26:256-268. [PMID: 29033008 DOI: 10.1016/j.ymthe.2017.09.014] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 09/05/2017] [Accepted: 09/09/2017] [Indexed: 11/17/2022] Open
Abstract
The aim of this study was the evaluation of the safety and efficacy of unilateral subretinal injection of the adeno-associated vector (AAV) serotypes 2 and 4 (AAV2/4) RPE65-RPE65 vector in patients with Leber congenital amaurosis (LCA) associated with RPE65 gene deficiency. We evaluated ocular and general tolerance and visual function up to 1 year after vector administration in the most severely affected eye in nine patients with retinal degeneration associated with mutations in the RPE65 gene. Patients received either low (1.22 × 1010 to 2 × 1010 vector genomes [vg]) or high (between 3.27 × 1010 and 4.8 × 1010 vg) vector doses. An ancillary study, in which six of the original nine patients participated, extended the follow-up period to 2-3.5 years. All patients showed good ophthalmological and general tolerance to the rAAV2/4-RPE65-RPE65 vector. We observed a trend toward improved visual acuity in patients with nystagmus, stabilization and improvement of the visual field, and cortical activation along visual pathways during fMRI analysis. OCT analysis after vector administration revealed no retinal thinning, except in cases of macular detachment. Our findings show that the rAAV2/4.RPE65.RPE65 vector was well tolerated in nine patients with RPE65-associated LCA. Efficacy parameters varied between patients during follow-up.
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Affiliation(s)
- Guylène Le Meur
- Ophthalmology Department, University Hospital Centre (CHU) de Nantes, Nantes, France; INSERM UMR 1089, University of Nantes, CHU de Nantes, Nantes France.
| | - Pierre Lebranchu
- Ophthalmology Department, University Hospital Centre (CHU) de Nantes, Nantes, France; UMR 6597 CNRS, Image and Video Communication Team, Institute for Research into Communications and Cybernetics of Nantes, Polytech Nantes, Nantes, France
| | - Fanny Billaud
- Ophthalmology Department, University Hospital Centre (CHU) de Nantes, Nantes, France
| | - Oumeya Adjali
- INSERM UMR 1089, University of Nantes, CHU de Nantes, Nantes France
| | | | | | - Yann Péréon
- Reference Centre for Neuromuscular Disorders, FILNEMUS, CHU de Nantes, Nantes, France
| | - Romain Valabregue
- Institut du Cerveau et de la Moelle épinière ICM, Centre for NeuroImaging Research (CENIR), Paris, France
| | - Catherine Ivan
- Ophthalmology Department, University Hospital Centre (CHU) de Nantes, Nantes, France
| | | | | | - Fabienne Rolling
- INSERM UMR 1089, University of Nantes, CHU de Nantes, Nantes France
| | - Michel Weber
- Ophthalmology Department, University Hospital Centre (CHU) de Nantes, Nantes, France; INSERM UMR 1089, University of Nantes, CHU de Nantes, Nantes France
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68
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Evidence from Blindness for a Cognitively Pluripotent Cortex. Trends Cogn Sci 2017; 21:637-648. [DOI: 10.1016/j.tics.2017.06.003] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 05/26/2017] [Accepted: 06/01/2017] [Indexed: 01/30/2023]
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69
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Brown HDH, Woodall RL, Kitching RE, Baseler HA, Morland AB. Using magnetic resonance imaging to assess visual deficits: a review. Ophthalmic Physiol Opt 2017; 36:240-65. [PMID: 27112223 PMCID: PMC4855621 DOI: 10.1111/opo.12293] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 02/15/2016] [Indexed: 01/25/2023]
Abstract
Purpose Over the last two decades, magnetic resonance imaging (MRI) has been widely used in neuroscience research to assess both structure and function in the brain in health and disease. With regard to vision research, prior to the advent of MRI, researchers relied on animal physiology and human post‐mortem work to assess the impact of eye disease on visual cortex and connecting structures. Using MRI, researchers can non‐invasively examine the effects of eye disease on the whole visual pathway, including the lateral geniculate nucleus, striate and extrastriate cortex. This review aims to summarise research using MRI to investigate structural, chemical and functional effects of eye diseases, including: macular degeneration, retinitis pigmentosa, glaucoma, albinism, and amblyopia. Recent Findings Structural MRI has demonstrated significant abnormalities within both grey and white matter densities across both visual and non‐visual areas. Functional MRI studies have also provided extensive evidence of functional changes throughout the whole of the visual pathway following visual loss, particularly in amblyopia. MR spectroscopy techniques have also revealed several abnormalities in metabolite concentrations in both glaucoma and age‐related macular degeneration. GABA‐edited MR spectroscopy on the other hand has identified possible evidence of plasticity within visual cortex. Summary Collectively, using MRI to investigate the effects on the visual pathway following disease and dysfunction has revealed a rich pattern of results allowing for better characterisation of disease. In the future MRI will likely play an important role in assessing the impact of eye disease on the visual pathway and how it progresses over time.
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Affiliation(s)
| | | | | | - Heidi A Baseler
- Department of Psychology, University of York, York, UK.,Hull York Medical School, University of York, York, UK
| | - Antony B Morland
- Department of Psychology, University of York, York, UK.,Hull York Medical School, University of York, York, UK
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70
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Beyeler M, Rokem A, Boynton GM, Fine I. Learning to see again: biological constraints on cortical plasticity and the implications for sight restoration technologies. J Neural Eng 2017; 14:051003. [PMID: 28612755 DOI: 10.1088/1741-2552/aa795e] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The 'bionic eye'-so long a dream of the future-is finally becoming a reality with retinal prostheses available to patients in both the US and Europe. However, clinical experience with these implants has made it apparent that the visual information provided by these devices differs substantially from normal sight. Consequently, the ability of patients to learn to make use of this abnormal retinal input plays a critical role in whether or not some functional vision is successfully regained. The goal of the present review is to summarize the vast basic science literature on developmental and adult cortical plasticity with an emphasis on how this literature might relate to the field of prosthetic vision. We begin with describing the distortion and information loss likely to be experienced by visual prosthesis users. We then define cortical plasticity and perceptual learning, and describe what is known, and what is unknown, about visual plasticity across the hierarchy of brain regions involved in visual processing, and across different stages of life. We close by discussing what is known about brain plasticity in sight restoration patients and discuss biological mechanisms that might eventually be harnessed to improve visual learning in these patients.
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Affiliation(s)
- Michael Beyeler
- Department of Psychology, University of Washington, Seattle, WA, United States of America. Institute for Neuroengineering, University of Washington, Seattle, WA, United States of America. eScience Institute, University of Washington, Seattle, WA, United States of America
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71
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Lu KH, Jeong JY, Wen H, Liu Z. Spontaneous activity in the visual cortex is organized by visual streams. Hum Brain Mapp 2017; 38:4613-4630. [PMID: 28608643 DOI: 10.1002/hbm.23687] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Revised: 06/05/2017] [Accepted: 06/07/2017] [Indexed: 12/12/2022] Open
Abstract
Large-scale functional networks have been extensively studied using resting state functional magnetic resonance imaging (fMRI). However, the pattern, organization, and function of fine-scale network activity remain largely unknown. Here, we characterized the spontaneously emerging visual cortical activity by applying independent component (IC) analysis to resting state fMRI signals exclusively within the visual cortex. In this subsystem scale, we observed about 50 spatially ICs that were reproducible within and across subjects, and analyzed their spatial patterns and temporal relationships to reveal the intrinsic parcellation and organization of the visual cortex. The resulting visual cortical parcels were aligned with the steepest gradient of cortical myelination, and were organized into functional modules segregated along the dorsal/ventral pathways and foveal/peripheral early visual areas. Cortical distance could partly explain intra-hemispherical functional connectivity, but not interhemispherical connectivity; after discounting the effect of anatomical affinity, the fine-scale functional connectivity still preserved a similar visual-stream-specific modular organization. Moreover, cortical retinotopy, folding, and cytoarchitecture impose limited constraints to the organization of resting state activity. Given these findings, we conclude that spontaneous activity patterns in the visual cortex are primarily organized by visual streams, likely reflecting feedback network interactions. Hum Brain Mapp 38:4613-4630, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Kun-Han Lu
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana.,Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, Indiana
| | - Jun Young Jeong
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana
| | - Haiguang Wen
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana.,Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, Indiana
| | - Zhongming Liu
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana.,Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, Indiana.,Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
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72
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Abstract
Cortex plasticity after hand amputation is considered harmful, causing phantom limb pain. A new study shows that cortical overtake can occur instead in a compensatory manner in people born with one hand, for multiple body parts used to overcome disability.
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73
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Domain Selectivity in the Parahippocampal Gyrus Is Predicted by the Same Structural Connectivity Patterns in Blind and Sighted Individuals. J Neurosci 2017; 37:4705-4716. [PMID: 28381591 DOI: 10.1523/jneurosci.3622-16.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 03/20/2017] [Accepted: 03/28/2017] [Indexed: 11/21/2022] Open
Abstract
Human ventral occipital temporal cortex contains clusters of neurons that show domain-preferring responses during visual perception. Recent studies have reported that some of these clusters show surprisingly similar domain selectivity in congenitally blind participants performing nonvisual tasks. An important open question is whether these functional similarities are driven by similar innate connections in blind and sighted groups. Here we addressed this question focusing on the parahippocampal gyrus (PHG), a region that is selective for large objects and scenes. Based on the assumption that patterns of long-range connectivity shape local computation, we examined whether domain selectivity in PHG is driven by similar structural connectivity patterns in the two populations. Multiple regression models were built to predict the selectivity of PHG voxels for large human-made objects from white matter (WM) connectivity patterns in both groups. These models were then tested using independent data from participants with similar visual experience (two sighted groups) and using data from participants with different visual experience (blind and sighted groups). Strikingly, the WM-based predictions between blind and sighted groups were as successful as predictions between two independent sighted groups. That is, the functional selectivity for large objects of a PHG voxel in a blind participant could be accurately predicted by its WM pattern using the connection-to-function model built from the sighted group data, and vice versa. Regions that significantly predicted PHG selectivity were located in temporal and frontal cortices in both sighted and blind populations. These results show that the large-scale network driving domain selectivity in PHG is independent of vision.SIGNIFICANCE STATEMENT Recent studies have reported intriguingly similar domain selectivity in sighted and congenitally blind individuals in regions within the ventral visual cortex. To examine whether these similarities originate from similar innate connectional roots, we investigated whether the domain selectivity in one population could be predicted by the structural connectivity pattern of the other. We found that the selectivity for large objects of a PHG voxel in a blind participant could be predicted by its structural connectivity pattern using the connection-to-function model built from the sighted group data, and vice versa. These results reveal that the structural connectivity underlying domain selectivity in the PHG is independent of visual experience, providing evidence for nonvisual representations in this region.
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74
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Task Selectivity as a Comprehensive Principle for Brain Organization. Trends Cogn Sci 2017; 21:307-310. [PMID: 28385460 DOI: 10.1016/j.tics.2017.03.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 03/10/2017] [Accepted: 03/15/2017] [Indexed: 11/24/2022]
Abstract
How do the anatomically consistent functional selectivities of the brain emerge? A new study by Bola and colleagues reveals task selectivity in auditory rhythm-selective areas in congenitally deaf adults perceiving visual rhythm sequences. Here, we contextualize this result with accumulating evidence from animal and human studies supporting sensory-independent task specializations as a comprehensive principle shaping brain (re)organization.
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75
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Bauer CM, Hirsch GV, Zajac L, Koo BB, Collignon O, Merabet LB. Multimodal MR-imaging reveals large-scale structural and functional connectivity changes in profound early blindness. PLoS One 2017; 12:e0173064. [PMID: 28328939 PMCID: PMC5362049 DOI: 10.1371/journal.pone.0173064] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 02/14/2017] [Indexed: 11/21/2022] Open
Abstract
In the setting of profound ocular blindness, numerous lines of evidence demonstrate the existence of dramatic anatomical and functional changes within the brain. However, previous studies based on a variety of distinct measures have often provided inconsistent findings. To help reconcile this issue, we used a multimodal magnetic resonance (MR)-based imaging approach to provide complementary structural and functional information regarding this neuroplastic reorganization. This included gray matter structural morphometry, high angular resolution diffusion imaging (HARDI) of white matter connectivity and integrity, and resting state functional connectivity MRI (rsfcMRI) analysis. When comparing the brains of early blind individuals to sighted controls, we found evidence of co-occurring decreases in cortical volume and cortical thickness within visual processing areas of the occipital and temporal cortices respectively. Increases in cortical volume in the early blind were evident within regions of parietal cortex. Investigating white matter connections using HARDI revealed patterns of increased and decreased connectivity when comparing both groups. In the blind, increased white matter connectivity (indexed by increased fiber number) was predominantly left-lateralized, including between frontal and temporal areas implicated with language processing. Decreases in structural connectivity were evident involving frontal and somatosensory regions as well as between occipital and cingulate cortices. Differences in white matter integrity (as indexed by quantitative anisotropy, or QA) were also in general agreement with observed pattern changes in the number of white matter fibers. Analysis of resting state sequences showed evidence of both increased and decreased functional connectivity in the blind compared to sighted controls. Specifically, increased connectivity was evident between temporal and inferior frontal areas. Decreases in functional connectivity were observed between occipital and frontal and somatosensory-motor areas and between temporal (mainly fusiform and parahippocampus) and parietal, frontal, and other temporal areas. Correlations in white matter connectivity and functional connectivity observed between early blind and sighted controls showed an overall high degree of association. However, comparing the relative changes in white matter and functional connectivity between early blind and sighted controls did not show a significant correlation. In summary, these findings provide complimentary evidence, as well as highlight potential contradictions, regarding the nature of regional and large scale neuroplastic reorganization resulting from early onset blindness.
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Affiliation(s)
- Corinna M. Bauer
- Laboratory for Visual Neuroplasticity. Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, United States of America
| | - Gabriella V. Hirsch
- Laboratory for Visual Neuroplasticity. Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, United States of America
| | - Lauren Zajac
- Center for Biomedical Imaging. Boston University School of Medicine, Boston, MA, United States of America
| | - Bang-Bon Koo
- Center for Biomedical Imaging. Boston University School of Medicine, Boston, MA, United States of America
| | - Olivier Collignon
- Crossmodal Perception and Plasticity Laboratory. University of Trento, Trento, Italy
| | - Lotfi B. Merabet
- Laboratory for Visual Neuroplasticity. Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, United States of America
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76
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Sabbah N, Sanda N, Authié CN, Mohand-Saïd S, Sahel JA, Habas C, Amedi A, Safran AB. Reorganization of early visual cortex functional connectivity following selective peripheral and central visual loss. Sci Rep 2017; 7:43223. [PMID: 28233790 PMCID: PMC5324137 DOI: 10.1038/srep43223] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 01/20/2017] [Indexed: 12/27/2022] Open
Abstract
Behavioral alterations emerging after central or peripheral vision loss suggest that cerebral reorganization occurs for both the afferented and deafferented early visual cortex (EVC). We explored the functional reorganization of the central and peripheral EVC following visual field defects specifically affecting central or peripheral vision. Compared to normally sighted, afferented central and peripheral EVC enhance their functional connectivity with areas involved in visual processing, whereas deafferented central and peripheral EVC increase their functional connectivity with more remote regions. The connectivity pattern of afferented EVC suggests adaptive changes that might enhance the visual processing capacity whereas the connectivity pattern of deafferented EVC may reflect the involvement of these regions in high-order mechanisms. Characterizing and understanding the plastic changes induced by these visual defects is essential for any attempt to develop efficient rehabilitation strategies.
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Affiliation(s)
- Norman Sabbah
- Sorbonne Universités, UPMC Université Paris 06, UMR S968, Institut de la Vision, Paris, F-75012, France.,INSERM, U968, Institut de la Vision, Paris, F-75012, France.,CNRS, UMR 7210, Institut de la Vision, Paris, F-75012, France.,Centre d'investigation clinique, Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, INSERM-DGOS CIC 1423, Paris, F-75012, France
| | - Nicolae Sanda
- Sorbonne Universités, UPMC Université Paris 06, UMR S968, Institut de la Vision, Paris, F-75012, France.,INSERM, U968, Institut de la Vision, Paris, F-75012, France.,CNRS, UMR 7210, Institut de la Vision, Paris, F-75012, France.,Centre d'investigation clinique, Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, INSERM-DGOS CIC 1423, Paris, F-75012, France.,Service de neurologie, Hôpital Foch, Suresnes, France
| | - Colas N Authié
- Sorbonne Universités, UPMC Université Paris 06, UMR S968, Institut de la Vision, Paris, F-75012, France.,INSERM, U968, Institut de la Vision, Paris, F-75012, France.,CNRS, UMR 7210, Institut de la Vision, Paris, F-75012, France.,Centre d'investigation clinique, Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, INSERM-DGOS CIC 1423, Paris, F-75012, France
| | - Saddek Mohand-Saïd
- Sorbonne Universités, UPMC Université Paris 06, UMR S968, Institut de la Vision, Paris, F-75012, France.,INSERM, U968, Institut de la Vision, Paris, F-75012, France.,CNRS, UMR 7210, Institut de la Vision, Paris, F-75012, France.,Centre d'investigation clinique, Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, INSERM-DGOS CIC 1423, Paris, F-75012, France
| | - José-Alain Sahel
- Sorbonne Universités, UPMC Université Paris 06, UMR S968, Institut de la Vision, Paris, F-75012, France.,INSERM, U968, Institut de la Vision, Paris, F-75012, France.,CNRS, UMR 7210, Institut de la Vision, Paris, F-75012, France.,Centre d'investigation clinique, Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, INSERM-DGOS CIC 1423, Paris, F-75012, France.,Institute of Ophthalmology, University College of London, United Kingdom.,Fondation Ophtalmologique Adolphe de Rothschild, Paris, France.,Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, US
| | - Christophe Habas
- Sorbonne Universités, UPMC Université Paris 06, UMR S968, Institut de la Vision, Paris, F-75012, France.,INSERM, U968, Institut de la Vision, Paris, F-75012, France.,CNRS, UMR 7210, Institut de la Vision, Paris, F-75012, France.,Centre de neuroimagerie, Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, Paris, F-75012, France
| | - Amir Amedi
- Sorbonne Universités, UPMC Université Paris 06, UMR S968, Institut de la Vision, Paris, F-75012, France.,INSERM, U968, Institut de la Vision, Paris, F-75012, France.,CNRS, UMR 7210, Institut de la Vision, Paris, F-75012, France.,Department of Medical Neurobiology, The Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91220, Israel.,The Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem 91220, Israel.,The Cognitive Science Program, The Hebrew University of Jerusalem, Jerusalem 91220, Israel
| | - Avinoam B Safran
- Sorbonne Universités, UPMC Université Paris 06, UMR S968, Institut de la Vision, Paris, F-75012, France.,INSERM, U968, Institut de la Vision, Paris, F-75012, France.,CNRS, UMR 7210, Institut de la Vision, Paris, F-75012, France.,Centre d'investigation clinique, Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, INSERM-DGOS CIC 1423, Paris, F-75012, France.,Department of Clinical Neurosciences, Geneva University School of Medicine, Geneva, Switzerland
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77
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Abstract
The principles that guide large-scale cortical reorganization remain unclear. In the blind, several visual regions preserve their task specificity; ventral visual areas, for example, become engaged in auditory and tactile object-recognition tasks. It remains open whether task-specific reorganization is unique to the visual cortex or, alternatively, whether this kind of plasticity is a general principle applying to other cortical areas. Auditory areas can become recruited for visual and tactile input in the deaf. Although nonhuman data suggest that this reorganization might be task specific, human evidence has been lacking. Here we enrolled 15 deaf and 15 hearing adults into an functional MRI experiment during which they discriminated between temporally complex sequences of stimuli (rhythms). Both deaf and hearing subjects performed the task visually, in the central visual field. In addition, hearing subjects performed the same task in the auditory modality. We found that the visual task robustly activated the auditory cortex in deaf subjects, peaking in the posterior-lateral part of high-level auditory areas. This activation pattern was strikingly similar to the pattern found in hearing subjects performing the auditory version of the task. Although performing the visual task in deaf subjects induced an increase in functional connectivity between the auditory cortex and the dorsal visual cortex, no such effect was found in hearing subjects. We conclude that in deaf humans the high-level auditory cortex switches its input modality from sound to vision but preserves its task-specific activation pattern independent of input modality. Task-specific reorganization thus might be a general principle that guides cortical plasticity in the brain.
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78
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Pelland M, Orban P, Dansereau C, Lepore F, Bellec P, Collignon O. State-dependent modulation of functional connectivity in early blind individuals. Neuroimage 2016; 147:532-541. [PMID: 28011254 DOI: 10.1016/j.neuroimage.2016.12.053] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 10/13/2016] [Accepted: 12/18/2016] [Indexed: 12/11/2022] Open
Abstract
Resting-state functional connectivity (RSFC) studies have provided strong evidences that visual deprivation influences the brain's functional architecture. In particular, reduced RSFC coupling between occipital (visual) and temporal (auditory) regions has been reliably observed in early blind individuals (EB) at rest. In contrast, task-dependent activation studies have repeatedly demonstrated enhanced co-activation and connectivity of occipital and temporal regions during auditory processing in EB. To investigate this apparent discrepancy, the functional coupling between temporal and occipital networks at rest was directly compared to that of an auditory task in both EB and sighted controls (SC). Functional brain clusters shared across groups and cognitive states (rest and auditory task) were defined. In EBs, we observed higher occipito-temporal correlations in activity during the task than at rest. The reverse pattern was observed in SC. We also observed higher temporal variability of occipito-temporal RSFC in EB suggesting that occipital regions in this population may play the role of a multiple demand system. Our study reveals how the connectivity profile of sighted and early blind people is differentially influenced by their cognitive state, bridging the gap between previous task-dependent and RSFC studies. Our results also highlight how inferring group-differences in functional brain architecture solely based on resting-state acquisition has to be considered with caution.
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Affiliation(s)
- Maxime Pelland
- Departement of Psychology, University of Montreal, Montreal, Quebec, Canada; Centre de Recherche en Neuropsychologie et Cognition, University of Montreal, Montreal, QC, Canada.
| | - Pierre Orban
- Functional Neuroimaging Unit, Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, University of Montreal, Montreal, Quebec, Canada; Department of Psychiatry, University of Montreal, Montreal, Quebec, Canada
| | - Christian Dansereau
- Functional Neuroimaging Unit, Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, University of Montreal, Montreal, Quebec, Canada; Department of Computer Science and Operations Research, University of Montreal, Montreal, Quebec, Canada
| | - Franco Lepore
- Departement of Psychology, University of Montreal, Montreal, Quebec, Canada; Centre de Recherche en Neuropsychologie et Cognition, University of Montreal, Montreal, QC, Canada
| | - Pierre Bellec
- Functional Neuroimaging Unit, Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, University of Montreal, Montreal, Quebec, Canada; Department of Computer Science and Operations Research, University of Montreal, Montreal, Quebec, Canada
| | - Olivier Collignon
- Institute of Psychology (IPSY) and Institute of Neuroscience (IoNS), Université catholique de Louvain, Belgium; CIMeC - Center for Mind/Brain Sciences, University of Trento, via delle Regole 101, Mattarello, TN, Italy.
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79
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Retinotopic information interacts with category selectivity in human ventral cortex. Neuropsychologia 2016; 92:90-106. [DOI: 10.1016/j.neuropsychologia.2016.05.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Revised: 04/07/2016] [Accepted: 05/20/2016] [Indexed: 11/19/2022]
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80
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Castaldi E, Cicchini GM, Cinelli L, Biagi L, Rizzo S, Morrone MC. Visual BOLD Response in Late Blind Subjects with Argus II Retinal Prosthesis. PLoS Biol 2016; 14:e1002569. [PMID: 27780207 PMCID: PMC5079588 DOI: 10.1371/journal.pbio.1002569] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 09/19/2016] [Indexed: 11/19/2022] Open
Abstract
Retinal prosthesis technologies require that the visual system downstream of the retinal circuitry be capable of transmitting and elaborating visual signals. We studied the capability of plastic remodeling in late blind subjects implanted with the Argus II Retinal Prosthesis with psychophysics and functional MRI (fMRI). After surgery, six out of seven retinitis pigmentosa (RP) blind subjects were able to detect high-contrast stimuli using the prosthetic implant. However, direction discrimination to contrast modulated stimuli remained at chance level in all of them. No subject showed any improvement of contrast sensitivity in either eye when not using the Argus II. Before the implant, the Blood Oxygenation Level Dependent (BOLD) activity in V1 and the lateral geniculate nucleus (LGN) was very weak or absent. Surprisingly, after prolonged use of Argus II, BOLD responses to visual input were enhanced. This is, to our knowledge, the first study tracking the neural changes of visual areas in patients after retinal implant, revealing a capacity to respond to restored visual input even after years of deprivation.
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Affiliation(s)
- E. Castaldi
- Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | | | - L. Cinelli
- Azienda Ospedaliero-Universitaria Careggi, SOD Oculistica, Florence, Italy
| | - L. Biagi
- Stella Maris Scientific Institute, Pisa, Italy
| | - S. Rizzo
- Azienda Ospedaliero-Universitaria Careggi, SOD Oculistica, Florence, Italy
| | - M. C. Morrone
- Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
- Stella Maris Scientific Institute, Pisa, Italy
- * E-mail:
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81
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Welton T, Ather S, Proudlock FA, Gottlob I, Dineen RA. Altered whole-brain connectivity in albinism. Hum Brain Mapp 2016; 38:740-752. [PMID: 27684406 DOI: 10.1002/hbm.23414] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 09/13/2016] [Accepted: 09/19/2016] [Indexed: 12/15/2022] Open
Abstract
Albinism is a group of congenital disorders of the melanin synthesis pathway. Multiple ocular, white matter and cortical abnormalities occur in albinism, including a greater decussation of nerve fibres at the optic chiasm, foveal hypoplasia and nystagmus. Despite this, visual perception is largely preserved. It was proposed that this may be attributable to reorganisation among cerebral networks, including an increased interhemispheric connectivity of the primary visual areas. A graph-theoretic model was applied to explore brain connectivity networks derived from resting-state functional and diffusion-tensor magnetic resonance imaging data in 23 people with albinism and 20 controls. They tested for group differences in connectivity between primary visual areas and in summary network organisation descriptors. Main findings were supplemented with analyses of control regions, brain volumes and white matter microstructure. Significant functional interhemispheric hyperconnectivity of the primary visual areas in the albinism group were found (P = 0.012). Tests of interhemispheric connectivity based on the diffusion-tensor data showed no significant group difference (P = 0.713). Second, it was found that a range of functional whole-brain network metrics were abnormal in people with albinism, including the clustering coefficient (P = 0.005), although this may have been driven partly by overall differences in connectivity, rather than reorganisation. Based on the results, it was suggested that changes occur in albinism at the whole-brain level, and not just within the visual processing pathways. It was proposed that their findings may reflect compensatory adaptations to increased chiasmic decussation, foveal hypoplasia and nystagmus. Hum Brain Mapp 38:740-752, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Thomas Welton
- Radiological Sciences, Division of Clinical Neuroscience, University of Nottingham, Room W/B 1441, Queen's Medical Centre, Derby Road, Nottingham, NG7 2UH, United Kingdom
| | - Sarim Ather
- Radiological Sciences, Division of Clinical Neuroscience, University of Nottingham, Room W/B 1441, Queen's Medical Centre, Derby Road, Nottingham, NG7 2UH, United Kingdom.,Leicester Royal Infirmary, Ulverscroft Eye Unit, Ophthalmology, University of Leicester, Knighton Street Offices, Leicester, LE2 7LX, United Kingdom
| | - Frank A Proudlock
- Leicester Royal Infirmary, Ulverscroft Eye Unit, Ophthalmology, University of Leicester, Knighton Street Offices, Leicester, LE2 7LX, United Kingdom
| | - Irene Gottlob
- Leicester Royal Infirmary, Ulverscroft Eye Unit, Ophthalmology, University of Leicester, Knighton Street Offices, Leicester, LE2 7LX, United Kingdom
| | - Robert A Dineen
- Radiological Sciences, Division of Clinical Neuroscience, University of Nottingham, Room W/B 1441, Queen's Medical Centre, Derby Road, Nottingham, NG7 2UH, United Kingdom
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82
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Kristjánsson Á, Moldoveanu A, Jóhannesson ÓI, Balan O, Spagnol S, Valgeirsdóttir VV, Unnthorsson R. Designing sensory-substitution devices: Principles, pitfalls and potential1. Restor Neurol Neurosci 2016; 34:769-87. [PMID: 27567755 PMCID: PMC5044782 DOI: 10.3233/rnn-160647] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
An exciting possibility for compensating for loss of sensory function is to augment deficient senses by conveying missing information through an intact sense. Here we present an overview of techniques that have been developed for sensory substitution (SS) for the blind, through both touch and audition, with special emphasis on the importance of training for the use of such devices, while highlighting potential pitfalls in their design. One example of a pitfall is how conveying extra information about the environment risks sensory overload. Related to this, the limits of attentional capacity make it important to focus on key information and avoid redundancies. Also, differences in processing characteristics and bandwidth between sensory systems severely constrain the information that can be conveyed. Furthermore, perception is a continuous process and does not involve a snapshot of the environment. Design of sensory substitution devices therefore requires assessment of the nature of spatiotemporal continuity for the different senses. Basic psychophysical and neuroscientific research into representations of the environment and the most effective ways of conveying information should lead to better design of sensory substitution systems. Sensory substitution devices should emphasize usability, and should not interfere with other inter- or intramodal perceptual function. Devices should be task-focused since in many cases it may be impractical to convey too many aspects of the environment. Evidence for multisensory integration in the representation of the environment suggests that researchers should not limit themselves to a single modality in their design. Finally, we recommend active training on devices, especially since it allows for externalization, where proximal sensory stimulation is attributed to a distinct exterior object.
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Affiliation(s)
- Árni Kristjánsson
- Laboratory of Visual Perception and Visuomotor control, University of Iceland, Faculty of Psychology, School of Health Sciences, Reykjavik, Iceland
| | - Alin Moldoveanu
- University Politehnica of Bucharest, Faculty of Automatic Control and Computers, Computer Science and Engineering Department, Bucharest, Romania
| | - Ómar I. Jóhannesson
- Laboratory of Visual Perception and Visuomotor control, University of Iceland, Faculty of Psychology, School of Health Sciences, Reykjavik, Iceland
| | - Oana Balan
- University Politehnica of Bucharest, Faculty of Automatic Control and Computers, Computer Science and Engineering Department, Bucharest, Romania
| | - Simone Spagnol
- Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, School of Engineering and Natural Sciences, Reykjavik, Iceland
| | - Vigdís Vala Valgeirsdóttir
- Laboratory of Visual Perception and Visuomotor control, University of Iceland, Faculty of Psychology, School of Health Sciences, Reykjavik, Iceland
| | - Rúnar Unnthorsson
- Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, School of Engineering and Natural Sciences, Reykjavik, Iceland
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83
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Griffis JC, Elkhetali AS, Burge WK, Chen RH, Bowman AD, Szaflarski JP, Visscher KM. Retinotopic patterns of functional connectivity between V1 and large-scale brain networks during resting fixation. Neuroimage 2016; 146:1071-1083. [PMID: 27554527 DOI: 10.1016/j.neuroimage.2016.08.035] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 08/18/2016] [Indexed: 11/16/2022] Open
Abstract
Psychophysical and neurobiological evidence suggests that central and peripheral vision are specialized for different functions. This specialization of function might be expected to lead to differences in the large-scale functional interactions of early cortical areas that represent central and peripheral visual space. Here, we characterize differences in whole-brain functional connectivity among sectors in primary visual cortex (V1) corresponding to central, near-peripheral, and far-peripheral vision during resting fixation. Importantly, our analyses reveal that eccentricity sectors in V1 have different functional connectivity with non-visual areas associated with large-scale brain networks. Regions associated with the fronto-parietal control network are most strongly connected with central sectors of V1, regions associated with the cingulo-opercular control network are most strongly connected with near-peripheral sectors of V1, and regions associated with the default mode and auditory networks are most strongly connected with far-peripheral sectors of V1. Additional analyses suggest that similar patterns are present during eyes-closed rest. These results suggest that different types of visual information may be prioritized by large-scale brain networks with distinct functional profiles, and provide insights into how the small-scale functional specialization within early visual regions such as V1 relates to the large-scale organization of functionally distinct whole-brain networks.
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Affiliation(s)
- Joseph C Griffis
- Department of Psychology, University of Alabama at Birmingham, United States
| | | | - Wesley K Burge
- Department of Psychology, University of Alabama at Birmingham, United States
| | - Richard H Chen
- Department of Neurobiology, University of Alabama at Birmingham, United States
| | - Anthony D Bowman
- Department of Biomedical Engineering, University of Alabama at Birmingham, United States
| | - Jerzy P Szaflarski
- Department of Neurology, University of Alabama at Birmingham, United States
| | - Kristina M Visscher
- Department of Neurobiology, University of Alabama at Birmingham, United States.
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84
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Murray MM, Lewkowicz DJ, Amedi A, Wallace MT. Multisensory Processes: A Balancing Act across the Lifespan. Trends Neurosci 2016; 39:567-579. [PMID: 27282408 PMCID: PMC4967384 DOI: 10.1016/j.tins.2016.05.003] [Citation(s) in RCA: 137] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 04/13/2016] [Accepted: 05/12/2016] [Indexed: 11/20/2022]
Abstract
Multisensory processes are fundamental in scaffolding perception, cognition, learning, and behavior. How and when stimuli from different sensory modalities are integrated rather than treated as separate entities is poorly understood. We review how the relative reliance on stimulus characteristics versus learned associations dynamically shapes multisensory processes. We illustrate the dynamism in multisensory function across two timescales: one long term that operates across the lifespan and one short term that operates during the learning of new multisensory relations. In addition, we highlight the importance of task contingencies. We conclude that these highly dynamic multisensory processes, based on the relative weighting of stimulus characteristics and learned associations, provide both stability and flexibility to brain functions over a wide range of temporal scales.
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Affiliation(s)
- Micah M Murray
- The Laboratory for Investigative Neurophysiology (The LINE), Department of Clinical Neurosciences and Department of Radiology, University Hospital Centre and University of Lausanne, Lausanne, Switzerland; Electroencephalography Brain Mapping Core, Centre for Biomedical Imaging (CIBM), Lausanne, Switzerland; Department of Ophthalmology, University of Lausanne, Jules Gonin Eye Hospital, Lausanne, Switzerland; Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - David J Lewkowicz
- Department of Communication Sciences and Disorders, Northeastern University, Boston, MA, USA
| | - Amir Amedi
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada (IMRIC), Hadassah Medical School, Hebrew University of Jerusalem, Jerusalem, Israel; Interdisciplinary and Cognitive Science Program, The Edmond & Lily Safra Center for Brain Sciences (ELSC), Hebrew University of Jerusalem, Jerusalem, Israel
| | - Mark T Wallace
- Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Psychology, Vanderbilt University, Nashville, TN, USA; Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN, USA; Department of Psychiatry, Vanderbilt University, Nashville, TN, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA.
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85
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Sabbah N, Authié CN, Sanda N, Mohand-Saïd S, Sahel JA, Safran AB, Habas C, Amedi A. Increased functional connectivity between language and visually deprived areas in late and partial blindness. Neuroimage 2016; 136:162-73. [DOI: 10.1016/j.neuroimage.2016.04.056] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 04/12/2016] [Accepted: 04/22/2016] [Indexed: 01/09/2023] Open
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86
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Striem-Amit E, Almeida J, Belledonne M, Chen Q, Fang Y, Han Z, Caramazza A, Bi Y. Topographical functional connectivity patterns exist in the congenitally, prelingually deaf. Sci Rep 2016; 6:29375. [PMID: 27427158 PMCID: PMC4947901 DOI: 10.1038/srep29375] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 06/10/2016] [Indexed: 12/26/2022] Open
Abstract
Congenital deafness causes large changes in the auditory cortex structure and function, such that without early childhood cochlear-implant, profoundly deaf children do not develop intact, high-level, auditory functions. But how is auditory cortex organization affected by congenital, prelingual, and long standing deafness? Does the large-scale topographical organization of the auditory cortex develop in people deaf from birth? And is it retained despite cross-modal plasticity? We identified, using fMRI, topographic tonotopy-based functional connectivity (FC) structure in humans in the core auditory cortex, its extending tonotopic gradients in the belt and even beyond that. These regions show similar FC structure in the congenitally deaf throughout the auditory cortex, including in the language areas. The topographic FC pattern can be identified reliably in the vast majority of the deaf, at the single subject level, despite the absence of hearing-aid use and poor oral language skills. These findings suggest that large-scale tonotopic-based FC does not require sensory experience to develop, and is retained despite life-long auditory deprivation and cross-modal plasticity. Furthermore, as the topographic FC is retained to varying degrees among the deaf subjects, it may serve to predict the potential for auditory rehabilitation using cochlear implants in individual subjects.
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Affiliation(s)
- Ella Striem-Amit
- Department of Psychology, Harvard University, Cambridge, MA 02138, USA
| | - Jorge Almeida
- Faculty of Psychology and Educational Sciences, University of Coimbra, Coimbra 3001-802, Portugal.,Proaction Laboratory, Faculty of Psychology and Educational Sciences, University of Coimbra, Coimbra 3001-802, Portugal
| | - Mario Belledonne
- Department of Psychology, Harvard University, Cambridge, MA 02138, USA
| | - Quanjing Chen
- State Key Laboratory of Cognitive Neuroscience and Learning &IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing 100875, China
| | - Yuxing Fang
- State Key Laboratory of Cognitive Neuroscience and Learning &IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing 100875, China
| | - Zaizhu Han
- State Key Laboratory of Cognitive Neuroscience and Learning &IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing 100875, China
| | - Alfonso Caramazza
- Department of Psychology, Harvard University, Cambridge, MA 02138, USA.,Center for Mind/Brain Sciences, University of Trento, 38068, Rovereto, Italy
| | - Yanchao Bi
- State Key Laboratory of Cognitive Neuroscience and Learning &IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing 100875, China
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87
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Rosenblum LD, Dias JW, Dorsi J. The supramodal brain: implications for auditory perception. JOURNAL OF COGNITIVE PSYCHOLOGY 2016. [DOI: 10.1080/20445911.2016.1181691] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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88
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Handjaras G, Ricciardi E, Leo A, Lenci A, Cecchetti L, Cosottini M, Marotta G, Pietrini P. How concepts are encoded in the human brain: A modality independent, category-based cortical organization of semantic knowledge. Neuroimage 2016; 135:232-42. [PMID: 27132545 DOI: 10.1016/j.neuroimage.2016.04.063] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 02/12/2016] [Accepted: 04/26/2016] [Indexed: 11/25/2022] Open
Abstract
How conceptual knowledge is represented in the human brain remains to be determined. To address the differential role of low-level sensory-based and high-level abstract features in semantic processing, we combined behavioral studies of linguistic production and brain activity measures by functional magnetic resonance imaging in sighted and congenitally blind individuals while they performed a property-generation task with concrete nouns from eight categories, presented through visual and/or auditory modalities. Patterns of neural activity within a large semantic cortical network that comprised parahippocampal, lateral occipital, temporo-parieto-occipital and inferior parietal cortices correlated with linguistic production and were independent both from the modality of stimulus presentation (either visual or auditory) and the (lack of) visual experience. In contrast, selected modality-dependent differences were observed only when the analysis was limited to the individual regions within the semantic cortical network. We conclude that conceptual knowledge in the human brain relies on a distributed, modality-independent cortical representation that integrates the partial category and modality specific information retained at a regional level.
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Affiliation(s)
- Giacomo Handjaras
- Dept. Surgical, Medical, Molecular Pathology and Critical Care, University of Pisa, Pisa 56126, Italy
| | - Emiliano Ricciardi
- Dept. Surgical, Medical, Molecular Pathology and Critical Care, University of Pisa, Pisa 56126, Italy
| | - Andrea Leo
- Dept. Surgical, Medical, Molecular Pathology and Critical Care, University of Pisa, Pisa 56126, Italy
| | - Alessandro Lenci
- Department of Philology, Literature, and Linguistics, University of Pisa, Pisa 56126, Italy
| | - Luca Cecchetti
- Dept. Surgical, Medical, Molecular Pathology and Critical Care, University of Pisa, Pisa 56126, Italy
| | | | - Giovanna Marotta
- Department of Philology, Literature, and Linguistics, University of Pisa, Pisa 56126, Italy
| | - Pietro Pietrini
- Dept. Surgical, Medical, Molecular Pathology and Critical Care, University of Pisa, Pisa 56126, Italy; Clinical Psychology Branch, Pisa University Hospital, Pisa 56126, Italy; IMT School for Advanced Studies Lucca, Lucca 55100, Italy.
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89
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Hasson U, Andric M, Atilgan H, Collignon O. Congenital blindness is associated with large-scale reorganization of anatomical networks. Neuroimage 2016; 128:362-372. [PMID: 26767944 PMCID: PMC4767220 DOI: 10.1016/j.neuroimage.2015.12.048] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 12/29/2015] [Accepted: 12/30/2015] [Indexed: 11/15/2022] Open
Abstract
Blindness is a unique model for understanding the role of experience in the development of the brain's functional and anatomical architecture. Documenting changes in the structure of anatomical networks for this population would substantiate the notion that the brain's core network-level organization may undergo neuroplasticity as a result of life-long experience. To examine this issue, we compared whole-brain networks of regional cortical-thickness covariance in early blind and matched sighted individuals. This covariance is thought to reflect signatures of integration between systems involved in similar perceptual/cognitive functions. Using graph-theoretic metrics, we identified a unique mode of anatomical reorganization in the blind that differed from that found for sighted. This was seen in that network partition structures derived from subgroups of blind were more similar to each other than they were to partitions derived from sighted. Notably, after deriving network partitions, we found that language and visual regions tended to reside within separate modules in sighted but showed a pattern of merging into shared modules in the blind. Our study demonstrates that early visual deprivation triggers a systematic large-scale reorganization of whole-brain cortical-thickness networks, suggesting changes in how occipital regions interface with other functional networks in the congenitally blind.
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Affiliation(s)
- Uri Hasson
- Center for Mind/Brain Sciences (CIMeC), University of Trento, Trento, Italy.
| | - Michael Andric
- Center for Mind/Brain Sciences (CIMeC), University of Trento, Trento, Italy
| | - Hicret Atilgan
- Center for Mind/Brain Sciences (CIMeC), University of Trento, Trento, Italy
| | - Olivier Collignon
- Center for Mind/Brain Sciences (CIMeC), University of Trento, Trento, Italy; CERNEC, Département de Psychologie, Université de Montréal, Montreal, QC, Canada
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90
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Lempert P. Re: Hoyt C.: What is next in amblyopia treatment? (Ophthalmology 2015;122:871-3). Ophthalmology 2016; 123:e8-9. [DOI: 10.1016/j.ophtha.2015.05.046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 05/22/2015] [Indexed: 10/22/2022] Open
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91
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Abstract
Early visual areas have neuronal receptive fields that form a sampling mosaic of visual space, resulting in a series of retinotopic maps in which the same region of space is represented in multiple visual areas. It is not clear to what extent the development and maintenance of this retinotopic organization in humans depend on retinal waves and/or visual experience. We examined the corticocortical receptive field organization of resting-state BOLD data in normally sighted, early blind, and anophthalmic (in which both eyes fail to develop) individuals and found that resting-state correlations between V1 and V2/V3 were retinotopically organized for all subject groups. These results show that the gross retinotopic pattern of resting-state connectivity across V1-V3 requires neither retinal waves nor visual experience to develop and persist into adulthood. Significance statement: Evidence from resting-state BOLD data suggests that the connections between early visual areas develop and are maintained even in the absence of retinal waves and visual experience.
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92
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Heimler B, Striem-Amit E, Amedi A. Origins of task-specific sensory-independent organization in the visual and auditory brain: neuroscience evidence, open questions and clinical implications. Curr Opin Neurobiol 2015; 35:169-77. [DOI: 10.1016/j.conb.2015.09.001] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 09/01/2015] [Accepted: 09/02/2015] [Indexed: 12/28/2022]
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93
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Reading in the dark: neural correlates and cross-modal plasticity for learning to read entire words without visual experience. Neuropsychologia 2015; 83:149-160. [PMID: 26577136 DOI: 10.1016/j.neuropsychologia.2015.11.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2015] [Revised: 11/03/2015] [Accepted: 11/09/2015] [Indexed: 12/17/2022]
Abstract
Cognitive neuroscience has long attempted to determine the ways in which cortical selectivity develops, and the impact of nature vs. nurture on it. Congenital blindness (CB) offers a unique opportunity to test this question as the brains of blind individuals develop without visual experience. Here we approach this question through the reading network. Several areas in the visual cortex have been implicated as part of the reading network, and one of the main ones among them is the VWFA, which is selective to the form of letters and words. But what happens in the CB brain? On the one hand, it has been shown that cross-modal plasticity leads to the recruitment of occipital areas, including the VWFA, for linguistic tasks. On the other hand, we have recently demonstrated VWFA activity for letters in contrast to other visual categories when the information is provided via other senses such as touch or audition. Which of these tasks is more dominant? By which mechanism does the CB brain process reading? Using fMRI and visual-to-auditory sensory substitution which transfers the topographical features of the letters we compare reading with semantic and scrambled conditions in a group of CB. We found activation in early auditory and visual cortices during the early processing phase (letter), while the later phase (word) showed VWFA and bilateral dorsal-intraparietal activations for words. This further supports the notion that many visual regions in general, even early visual areas, also maintain a predilection for task processing even when the modality is variable and in spite of putative lifelong linguistic cross-modal plasticity. Furthermore, we find that the VWFA is recruited preferentially for letter and word form, while it was not recruited, and even exhibited deactivation, for an immediately subsequent semantic task suggesting that despite only short sensory substitution experience orthographic task processing can dominate semantic processing in the VWFA. On a wider scope, this implies that at least in some cases cross-modal plasticity which enables the recruitment of areas for new tasks may be dominated by sensory independent task specific activation.
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94
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Wang X, Peelen MV, Han Z, He C, Caramazza A, Bi Y. How Visual Is the Visual Cortex? Comparing Connectional and Functional Fingerprints between Congenitally Blind and Sighted Individuals. J Neurosci 2015; 35:12545-59. [PMID: 26354920 PMCID: PMC6605405 DOI: 10.1523/jneurosci.3914-14.2015] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 07/16/2015] [Accepted: 07/22/2015] [Indexed: 02/02/2023] Open
Abstract
Classical animal visual deprivation studies and human neuroimaging studies have shown that visual experience plays a critical role in shaping the functionality and connectivity of the visual cortex. Interestingly, recent studies have additionally reported circumscribed regions in the visual cortex in which functional selectivity was remarkably similar in individuals with and without visual experience. Here, by directly comparing resting-state and task-based fMRI data in congenitally blind and sighted human subjects, we obtained large-scale continuous maps of the degree to which connectional and functional "fingerprints" of ventral visual cortex depend on visual experience. We found a close agreement between connectional and functional maps, pointing to a strong interdependence of connectivity and function. Visual experience (or the absence thereof) had a pronounced effect on the resting-state connectivity and functional response profile of occipital cortex and the posterior lateral fusiform gyrus. By contrast, connectional and functional fingerprints in the anterior medial and posterior lateral parts of the ventral visual cortex were statistically indistinguishable between blind and sighted individuals. These results provide a large-scale mapping of the influence of visual experience on the development of both functional and connectivity properties of visual cortex, which serves as a basis for the formulation of new hypotheses regarding the functionality and plasticity of specific subregions. Significance statement: How is the functionality and connectivity of the visual cortex shaped by visual experience? By directly comparing resting-state and task-based fMRI data in congenitally blind and sighted subjects, we obtained large-scale continuous maps of the degree to which connectional and functional "fingerprints" of ventral visual cortex depend on visual experience. In addition to revealing regions that are strongly dependent on visual experience (early visual cortex and posterior fusiform gyrus), our results showed regions in which connectional and functional patterns are highly similar in blind and sighted individuals (anterior medial and posterior lateral ventral occipital temporal cortex). These results serve as a basis for the formulation of new hypotheses regarding the functionality and plasticity of specific subregions of the visual cortex.
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Affiliation(s)
- Xiaoying Wang
- State Key Laboratory of Cognitive Neuroscience and Learning and IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing 100875, China
| | - Marius V Peelen
- Center for Mind/Brain Sciences, University of Trento, 38068 Rovereto, Italy, and
| | - Zaizhu Han
- State Key Laboratory of Cognitive Neuroscience and Learning and IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing 100875, China
| | - Chenxi He
- State Key Laboratory of Cognitive Neuroscience and Learning and IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing 100875, China
| | - Alfonso Caramazza
- Center for Mind/Brain Sciences, University of Trento, 38068 Rovereto, Italy, and Department of Psychology, Harvard University, Cambridge, Massachusetts 02138
| | - Yanchao Bi
- State Key Laboratory of Cognitive Neuroscience and Learning and IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing 100875, China,
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95
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Silson EH, Chan AWY, Reynolds RC, Kravitz DJ, Baker CI. A Retinotopic Basis for the Division of High-Level Scene Processing between Lateral and Ventral Human Occipitotemporal Cortex. J Neurosci 2015; 35:11921-35. [PMID: 26311774 PMCID: PMC4549403 DOI: 10.1523/jneurosci.0137-15.2015] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 07/20/2015] [Accepted: 07/23/2015] [Indexed: 11/21/2022] Open
Abstract
In humans, there is a repeated category-selective organization across the lateral and ventral surfaces of the occipitotemporal cortex. This apparent redundancy is often explained as a feedforward hierarchy, with processing within lateral areas preceding the processing within ventral areas. Here, we tested the alternative hypothesis that this structure better reflects distinct high-level representations of the upper (ventral surface) and lower (lateral surface) contralateral quadrants of the visual field, consistent with anatomical projections from early visual areas to these surfaces in monkey. Using complex natural scenes, we provide converging evidence from three independent functional imaging and behavioral studies. First, population receptive field mapping revealed strong biases for the contralateral upper and lower quadrant within the ventral and lateral scene-selective regions, respectively. Second, these same biases were observed in the position information available both in the magnitude and multivoxel response across these areas. Third, behavioral judgments of a scene property strongly represented within the ventral scene-selective area (open/closed), but not another equally salient property (manmade/natural), were more accurate in the upper than the lower field. Such differential representation of visual space poses a substantial challenge to the idea of a strictly hierarchical organization between lateral and ventral scene-selective regions. Moreover, such retinotopic biases seem to extend beyond these regions throughout both surfaces. Thus, the large-scale organization of high-level extrastriate cortex likely reflects the need for both specialized representations of particular categories and constraints from the structure of early vision. SIGNIFICANCE STATEMENT One of the most striking findings in fMRI has been the presence of matched category-selective regions on the lateral and ventral surfaces of human occipitotemporal cortex. Here, we focus on scene-selective regions and provide converging evidence for a retinotopic explanation of this organization. Specifically, we demonstrate that scene-selective regions exhibit strong biases for different portions of the visual field, with the lateral region representing the contralateral lower visual field and the ventral region the contralateral upper visual field. These biases are consistent with the retinotopy found in the early visual areas that lie directly antecedent to category-selective areas on both surfaces. Furthermore, these biases extend beyond scene-selective cortex and provide a retinotopic basis for the large-scale organization of occipitotemporal cortex.
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Affiliation(s)
| | - Annie Wai-Yiu Chan
- Laboratory of Brain and Cognition and Department of Neurology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, and
| | - Richard Craig Reynolds
- Scientific and Statistical Computing Core, National Institute of Mental Health, Bethesda, Maryland 20892-1366
| | - Dwight Jacob Kravitz
- Laboratory of Brain and Cognition and Department of Psychology, The George Washington University, Washington, DC 20052
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96
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Heine L, Bahri MA, Cavaliere C, Soddu A, Laureys S, Ptito M, Kupers R. Prevalence of increases in functional connectivity in visual, somatosensory and language areas in congenital blindness. Front Neuroanat 2015; 9:86. [PMID: 26190978 PMCID: PMC4486836 DOI: 10.3389/fnana.2015.00086] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 06/15/2015] [Indexed: 12/16/2022] Open
Abstract
There is ample evidence that congenitally blind individuals rely more strongly on non-visual information compared to sighted controls when interacting with the outside world. Although brain imaging studies indicate that congenitally blind individuals recruit occipital areas when performing various non-visual and cognitive tasks, it remains unclear through which pathways this is accomplished. To address this question, we compared resting state functional connectivity in a group of congenital blind and matched sighted control subjects. We used a seed-based analysis with a priori specified regions-of-interest (ROIs) within visual, somato-sensory, auditory and language areas. Between-group comparisons revealed increased functional connectivity within both the ventral and the dorsal visual streams in blind participants, whereas connectivity between the two streams was reduced. In addition, our data revealed stronger functional connectivity in blind participants between the visual ROIs and areas implicated in language and tactile (Braille) processing such as the inferior frontal gyrus (Broca's area), thalamus, supramarginal gyrus and cerebellum. The observed group differences underscore the extent of the cross-modal reorganization in the brain and the supra-modal function of the occipital cortex in congenitally blind individuals.
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Affiliation(s)
- Lizette Heine
- Coma Science Group, Cyclotron Research Center and Neurology Department, University and University Hospital of Liège Liège, Belgium
| | - Mohamed A Bahri
- Cyclotron Research Centre, University of Liège Liège, Belgium
| | - Carlo Cavaliere
- Coma Science Group, Cyclotron Research Center and Neurology Department, University and University Hospital of Liège Liège, Belgium ; IRCCS SDN, Istituto di Ricerca Diagnostica e Nucleare Naples, Italy
| | - Andrea Soddu
- Physics and Astronomy Department, Brain and Mind Institute, Western University London, ON, Canada
| | - Steven Laureys
- Coma Science Group, Cyclotron Research Center and Neurology Department, University and University Hospital of Liège Liège, Belgium
| | - Maurice Ptito
- Harland Sanders Chair, School of Optometry, University of Montreal Montreal, QC, Canada ; Brain Research and Integrative Neuroscience Laboratory, Department of Neuroscience and Pharmacology, University of Copenhagen Copenhagen, Denmark ; Laboratory of Neuropsychiatry, Psychiatric Centre Copenhagen and Department of Neuroscience and Pharmacology, University of Copenhagen Copenhagen, Denmark
| | - Ron Kupers
- Harland Sanders Chair, School of Optometry, University of Montreal Montreal, QC, Canada ; Brain Research and Integrative Neuroscience Laboratory, Department of Neuroscience and Pharmacology, University of Copenhagen Copenhagen, Denmark
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