AN INVESTIGATION INTO THE INVOLVEMENT OF THE VISUAL CORTEX IN AUDITORY LANGUAGE PROCESSING AND VERBAL WORKING MEMORY IN EARLY BLIND INDIVIDUALS

Abstract

This fMRI study compared brain activity in early blind and sighted individuals to; 1) determine how linguistic information reaches the visual cortex in blind individuals via effective connections from the language network and, 2) determine if increased working memory load leads to increased visual cortex recruitment and if behavioural measurements of verbal working memory ability correlate to visual cortex activity. First, dynamic causal modelling demonstrated an endogenous connection from the visual word form area to the visual cortex in blind participants, which was positively modulated by semantic and phonological processing. Second, increasing verbal working memory demands led to more widespread recruitment of the visual cortex in blind participants, however verbal working memory performance did not correlate to visual cortex recruitment. This work provides evidence regarding the processes that reshape the neural systems underlying cognition in blind individuals and clarifies the impact of the reorganization of cognitive networks on cognitive ability.