Task Selectivity as a Comprehensive Principle for Brain Organization

Amedi, Amir; Hofstetter, Shir; Maidenbaum, Shachar; Heimler, Benedetta

doi:10.1016/j.tics.2017.03.007

Cited by 80 publications

(102 citation statements)

References 13 publications

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“…In complete blindness or deafness there are no competing inputs within the sensory modality into the early sensory cortices, which could take over deprived parts of the topographic organization. Therefore, while the functional role of these regions is still debated (31)(32)(33), the topographic organization in the early stations of the hierarchy are retained (34,35). In higher stations of the cortical processing, the visual and auditory cortices also receive inputs from other modalities and from downstream cortical stations via feedback connectivity, which become more dominant in the complete absence of visual input.…”

Section: Discussionmentioning

confidence: 99%

Limitations of compensatory plasticity: the organization of the primary sensorimotor cortex in foot-using bilateral upper limb dysplasics

Striem-Amit

Vannuscorps

Caramazza

2017

Preprint

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What forces direct brain organization and its plasticity? When a brain region is deprived of its input would this region reorganize based on compensation for the disability and experience, or would strong limitations of brain structure limit its plasticity? People born without hands activate their sensorimotor hand region while moving body parts used to compensate for this ability (e.g. their feet). This has been taken to suggest an organization based on functions, such as performing manual-like dexterous actions, rather than on body parts. Here we test the selectivity for functionally-compensatory body parts in the sensorimotor cortex of people born without hands. Despite clear compensatory foot use, the sensorimotor hand area in the dysplasic subjects showed preference for non-compensatory body parts whose cortical territory is close to the hand area. This suggests that function-based organization, originally proposed for full congenital blindness and deafness, does not apply to cases of the primary sensorimotor cortex in dysplasia. This is consistent with the idea that experience-independent functional specialization occurs at relatively high levels of representation. Furthermore, it stresses the roles of neuroanatomical constraints such as topographical proximity and connectivity in determining the functional development of brain regions. These findings reveal limitations to brain plasticity and to the role of experience in shaping the functional organization of the brain.

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Section: Discussionmentioning

confidence: 99%

Limitations of compensatory plasticity: the organization of the primary sensorimotor cortex in foot-using bilateral upper limb dysplasics

Striem-Amit

Vannuscorps

Caramazza

2017

Preprint

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“…Our results further extend the task machine view of brain organization to dorsal stream retinotopic areas and for the first time also to early topographic retinotopic areas such as the primary visual cortex. This is a key addition to converging evidence from the ventral stream and MT of the blind and high-order temporal cortex of the deaf (reviewed in Amedi et al, 2017).…”

Section: Discussionmentioning

confidence: 83%

Human Navigation Without and With Vision - the Role of Visual Experience and Visual Regions

Maidenbaum

Chebat

Amedi

2018

Preprint

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Human navigation relies on a wide range of visual retinotopic cortical regions yet the precise role that these regions play in navigation remains unclear. Are these regions mainly sensory input channels or also modality-independent spatial processing centers? Accordingly, will they be recruited for navigation also without vision, such as via audition? Will visual experience, or the lack thereof, affect this recruitment? Sighted, congenitally blind and sighted-blindfolded participants actively navigated virtual mazes during fMRI scanning before and after navigating them in the real world. Participants used the EyeCane visual-to-auditory navigation aid for non-visual navigation.We found that retinotopic regions, including both dorsal stream regions (e.g. V6) and primary regions (e.g. peripheral V1), were selectively recruited for non-visual navigation only after the participants mastered the EyeCane demonstrating rapid plasticity for non-visual navigation. The hippocampus, considered the navigation network’s core, displayed negative BOLD in all groups.Our results demonstrate the robustness of the retinotopic nodes modality-independent spatial role in non-visual human navigation to lifelong visual-deprivation, demonstrating that visual input during development is not required for their recruitment. Furthermore, our results with the blindfolded group demonstrate this recruitment’s robustness even to brief blindfolding, but only after brief training, demonstrating rapid task based plasticity. These results generalize the wider framework of task-selectivity rather than input-modality as a brain organization principle to dorsal-stream retinotopic areas and even for the first time to the primary visual cortex.HighlightsBoth visual and non-visual navigation recruit retinotopic regionsAfter training blindfolded subjects selectively recruit V1 & V6 for navigationThis holds also for participants with no visual experience (congenitally blind)The medial temporal lobe showed non-selective Negative BOLD in all groupsDeclaration of interestsAll authors declare that they have no conflicts of interests.

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“…Studies of sensory loss demonstrate that experience can change the sensory modality to which a cortical area responds. However, the extent to which cortical regions truly change their function, even in cross-modal plasticity remains debated (Amedi, Hofstetter, Maidenbaum, & Heimler, 2017;Bavelier & Neville, 2002;Bedny, 2017).…”

Section: Introductionmentioning

confidence: 99%

“…One view is that sensory cortices preserve their original cognitive operation, even in cases of cross-modal plasticity (Amedi et al, 2017;Cecchetti, Kupers, Ptito, Pietrini, & Ricciardi, 2016;Meredith et al, 2011;Pascual-Leone & Hamilton, 2001;Renier et al, 2010;Striem-Amit, Dakwar, Reich, & Amedi, 2011). According to the metamodal hypothesis, in blindness, "visual" cortices continue to perform vision-like functions, but over input from audition and touch.…”

Section: Introductionmentioning

confidence: 99%

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

Loiotile

Bedny

2018

Preprint

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

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Task Selectivity as a Comprehensive Principle for Brain Organization

Cited by 80 publications

References 13 publications

Limitations of compensatory plasticity: the organization of the primary sensorimotor cortex in foot-using bilateral upper limb dysplasics

Limitations of compensatory plasticity: the organization of the primary sensorimotor cortex in foot-using bilateral upper limb dysplasics

Human Navigation Without and With Vision - the Role of Visual Experience and Visual Regions

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

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