Abstract
Restoring vision in blind people is an important goal and can be achieved in certain cases, for instance by performing cataract surgeries in children. However, reconnecting the visual system alone is not sufficient; the visual cortex needs to be rewired. In order to fully appreciate visual information, a mental representation of the world needs to be created. Here we are presenting fMRI data from the visual cortex of blind people when they were perceiving faces, houses, and geometric shapes encoded into sounds by means of a sensory substitution device (SSD). Specifically, we focused on selective visual brain areas related to this perception: the fusiform face area (FFA), the lateral occipital complex (LOC) and the parahippocampal place area (PPA). Each area was identified in sighted subjects under visual conditions using a functional localizer consisting of pictures of famous persons, visual 2-D geometric shapes and real houses. Then, region-of-interest analyses were performed on the data acquired in both Congenitally Blind (CB) and Sighted Control (SC) subjects when the SSD was used to discriminate schematic drawings of faces, geometric shapes and houses. Our results indicate that the left LOC was activated under all three conditions in both groups, while the left FFA was activated in CB subjects selectively during the SSD-face discrimination condition. No significant brain activity was found in the PPA in CB or SC subjects at the group level. The specific recruitment of the FFA during the perception of sound-encoded faces in CB subjects shows that they can extract visual information from sound-encoded objects and such perception activates the appropriate module in the visual cortex. Our study also represents new evidence about the developmental constraints on functional specialization in the absence of visual inputs.
Meeting abstract presented at VSS 2015