Fred_Behrmann_final_version

2020-05-11T22:39:08Z (GMT) by Erez Freud Marlene Behrmann
preprint of the paper. abstract:
Recent findings suggest that both dorsal and ventral visual pathways process shape information.
Nevertheless, a lesion to the ventral pathway alone can result in visual agnosia, an impairment in
shape perception. Here, we explored the neural basis of shape processing in a patient with visual
agnosia following a circumscribed right hemisphere ventral lesion and evaluated longitudinal
changes in the neural profile of shape representations. The results revealed a reduction of shape
sensitivity slopes along the patient’s right ventral pathway and a similar reduction in the
contralesional left ventral pathway. Remarkably, posterior parts of the dorsal pathway bilaterally
also evinced a reduction in shape sensitivity. These findings were similar over a two-year
interval, revealing that a focal cortical lesion can lead to persistent large-scale alterations of the
two visual pathways. These alterations are consistent with the view that a distributed network of
regions contributes to shape perception.