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Daan Wesselink, Sanne Kikkert, Holly Bridge, Tamar Makin; Sensorimotor finger-specific information in the cortex of the congenitally blind. Journal of Vision 2018;18(10):99. doi: https://doi.org/10.1167/18.10.99.
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© ARVO (1962-2015); The Authors (2016-present)
Regions of the occipital and temporal cortices, used for vision in sighted people, are activated by touch in the congenital absence of vision. It is unclear whether such occipitotemporal activity reflects low-level sensorimotor or higher-order amodal processing. To test this, we probed hand representation using ultra high-field (7T) fMRI in four individuals with bilateral congenital anophthalmia (a condition in which the eyes fail to develop) and eight blindfolded sighted control participants. All participants performed an active tapping task with each finger of the right hand (1 mm3 resolution, limited field of view capturing the supplementary motor area (SMA), primary somatosensory cortex (S1) and the lateral occipitotemporal cortex (LOTC). To determine whether a certain area displayed canonical low-level sensorimotor organisation we compared finger individuation in that area, as measured using multivariate pattern analysis (MVPA). Additionally, we compared inter-finger overlap in representation patterns to the pattern observed in finger-selective SI. In line with previous reports, 3/4 anophthalmic but no sighted participants showed bilateral activation in the LOTC during finger movements (70% of SI's levels). While the analysis did not reveal S1-like organization in LOTC in either group, the activity patterns induced by individual fingers could be separated: A cross-validated multivariate classifier (neural network; 1 hidden layer of 10 nodes; trained on 7 out of 8 runs) showed significant above-chance performance on finger classification in LOTC (5/6 hemispheres, 27% on average versus 20% chance). By comparison, the same analysis performed 38% in SMA and 88% in SI. None of the sighted participants showed above-chance finger classification in LOTC. To conclude, LOTC is strongly activated during simple hand movements in congenitally blind individuals. While not organised canonically, this activity contains information about individual fingers, suggesting the presence of low-level sensorimotor processes in the blind, not found in the sighted brain.
Meeting abstract presented at VSS 2018
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