Abstract
Humans acquire significant visual abilities within the first few months of life. However, the neural changes accompanying these early stages of development have been hard to elucidate due to the operational difficulties of imaging very young children. By the time the children are old enough to be cooperative subjects in such studies, they have already passed major developmental milestones. We report here our results from Project Prakash, an initiative that provides an unusual opportunity to address this question by studying congenitally blind adults whose sight we were able to restore. Past work from our laboratory has behaviorally documented the significant gains in visual proficiency the congenitally blind individuals exhibit as a function of time after sight restoring surgery. These results motivate an examination of changes in brain organization after sight onset. Contrary to our prior understanding of critical periods for visual development, we find strong evidence of brain plasticity in these individuals. More specifically, using functional connectivity analyses, we find that there is a significant enhancement of cortical decorrelation as a function of time following the onset of sight. Additionally, we find marked changes in the functional specialization of the visual cortex. Regions of the brain selective for facial responses, including the fusiform facial area (FFA) and occipital facial area (OFA), develop non-monotonically after the onset of sight. These findings have important implications for our understanding of brain plasticity, the developmental progression of functional specialization and the heretofore largely theoretical notions of the development of efficient coding in the brain.
NIH, James McDonnell Foundation.