The way of the light: how visual information reaches the auditory cortex in congenitally deaf adults

Human and animal studies on cross-modal plasticity under congenital deafness suggest that early auditory cortex plays a significant role in the processing of visual information when congenitally deprived from its typical (auditory) input. However, the pathway by which early auditory cortex is fed with visual information is still understudied. Here we focused on addressing how visual information reaches the auditory cortex under congenital deafness. We put forth a mechanistic model that proposes that different corticocortical and subcortical connections play a central role in rerouting visual information to the early auditory cortex of congenitally deaf individuals. Specifically, we show, using Representational Connectivity Analysis (RCA) and Dynamic Causal Modeling (DCM), that connections from the right superior colliculus to the right inferior colliculus, as well as connections from right early visual cortical regions to the right early auditory cortex play a role in rerouting visual information to early auditory cortex in congenitally deaf individuals. These findings shed light on how visual information reaches the early auditory cortex of deaf individuals - specifically, they suggest that neuroplasticity reshapes subcortical connections in order to re-route visual information to the auditory stream.