Preserved Cortical Organization in the Absence of Early Visual Input

Recent studies on blind humans suggest that retinotopy persists even in the absence of retinal input. Hubel and Wiesel found that monocular deprivation resulted in profound changes in V1 architecture, but binocular deprivation did not. After binocular deprivation, early visual cortical areas seemed normal, but the animals were behaviorally blind. We therefore asked whether binocular deprivation altered the large-scale organization of higher visual areas. We tracked the functional development of visual cortex in two monkeys that were raised for the first year of life only experiencing diffuse-light through binocular suturing. We scanned these monkeys using fMRI in a variety of visual tasks and under rest conditions starting as early as 8 days and throughout the deprivation period. During deprivation, spontaneous activity patterns throughout visual cortex reflected the retinotopic organization typically found in normally-reared monkeys. Visual stimulation resulted in decreased activity relative to baseline. However, increased activity was found to coarse bar motion specifically within areas MT, V6, and LIP. Behaviorally, these monkeys learned to navigate in their cages such that it was difficult to differentiate them from the rest of the colony. After a year, eyelids were re-opened and they received visual form stimulation. Strikingly, both monkeys are behaviorally insensitive to visual stimulation. However, visual stimulation evokes strong positive responses throughout the visual system. Spatial frequency mapping revealed an eccentricity organization similar to normally-reared monkeys. Visual stimulation resulted in strong responses in inferotemporal cortex, but no differential between face, object, and hand categories. Our results demonstrate that visual cortex is retinotopically organized even in monkeys raised with no visual form experience. Despite this substantial organization, the monkeys were behaviorally blind, suggesting that the primate brain is immature at birth, and the organization that supports visual perception is heavily dependent on early experience. Meeting abstract presented at VSS 2018