Abstract
How do innate predispositions interact with experience to produce functional specialization in the human brain? We address this question by studying the function of V1 in congenitally blind individuals. We first asked whether foveal and peripheral V1 experience different patterns of plasticity in blindness. Second, we asked whether this sub-specialization of function within V1 is predicted by the functional connectivity biases of foveal as opposed to peripheral V1. Congenitally blind (n=17) and sighted adults (n=19) underwent fMRI while performing a math task and a language comprehension task. In the math task, participants judged whether the value of an unknown variable was the same across two equations (e.g. 7-2=x, 8-3=x). Equation difficulty was manipulated by using either single- or double-digit math equations (e.g. 7-2=x vs. 27-12=x) and by manipulating the algebraic complexity of math equations (e.g. 7-2=x vs. x-2=7). In the language task, participants answered yes/no questions about sentences. A subset of these blind (n=13) and sighted (n=9) adults completed a resting state scan. Peripheral and foveal V1 showed different functional profiles in congenitally blind individuals. Whereas foveal V1 responded more to math equations and was sensitive to equation difficulty, peripheral V1 responded more to sentences and was sensitive to syntactic complexity. This functional dissociation was related to resting state correlations. Whereas foveal V1 was correlated with math-responsive regions in dorsal prefrontal cortex, peripheral V1 was correlated with language responsive regions in inferior frontal cortex. Crucially, these biases in resting state correlations were observed even in the sighted group, in whom V1 was not sensitive to either the language or number tasks. These results suggest that visual cortex plasticity in blindness builds upon pre-existing connectivity biases. That is, the consequences of these connectivity biases on cortical function depend on visual experience.
Meeting abstract presented at VSS 2016