A multi-site image-based data sharing initiative to assess structural brain changes in large cohorts of early and late blind individuals

Blindness is a widely studied phenomena in order to under- stand the neuroplasticity in case of sensory deprivation. Num- ber of studies focusing on the structural plasticity during vi- sual deprivation is fewer compared to the functional plastic- ity. In addition, samples and the results of those studies are heterogeneous. This dissertation utilized the largest dataset of MRI of blind subjects, that is gathered by the efforts of 10 different research labs. The aim was to overcome the previ- ous challenges, and identify pre- and post-natal factors that are confounding the results. In the first chapter, an extensive literature review revealing the current status of the field and identifying the problems is presented. The review is com- pleted with a systematic meta-analysis. Structural plasticity in case of congenital blindness was examined in chapter 3. This chapter focused on between (congenital blind partici- pants versus sighted controls) and within group (effect of the causes of blindness, residual light perception, Braille literacy) differences via utilizing voxel- and surface-based morphom- etry. In chapter 4, participants with late blindness was exam- ined. In addition to the analyses conducted on the congenital blind subjects, effect of time spent as blind and blindness on- set on neuroplasticity was examined. The results indicate a consistent atrophy on the visual pathway, and a critical pe- riod for vulnerability. In addition, the effect of premature birth, residual light perception, Braille literacy on the struc- tural plasticity and limited sample sizes on the results were revealed.