Do visual cortices in the blind activate to language processing demands?

Abstract

The fate of the occipital cortices in the blind has been of considerable interest in neuroscience to investigate whether and how much brain regions change with experience. Neuroimaging shows that the occipital cortices in the blind are activated during all kinds of non-visual tasks. In our previous study, we recently showed that all visual regions become MD regions and activate in response to any kind of control demand in the blind. Therefore, we hypothesized that the activation of the deprived visual cortex in language tasks in the literature is related to high cognitive control demand rather than language processing. This means that if V1 is involved in cognitive control demand, then it should not be activated in the passive listening task. Therefore, the study investigates whether the primary visual cortex (V1) in blind subjects participates in cognitive functions, particularly language processing, during a passive listening task with minimal cognitive control demand. Using fMRI, we compared whole brain and region of interest (ROI) activations in blind, and sighted participants across multiple areas, including occipital, language, and multiple demand (MD) regions. Results revealed no significant activation in V1 across all groups during the passive listening task, suggesting task-dependent limitations in the integration of V1 into higher-order cognitive processes rather than language. Furthermore, no significant differences in language or MD area activity were observed between blind and sighted participants. These findings challenge previous evidence on the occipital cortex becoming a language region in the blind and emphasize the importance of task complexity in modulating such interpretation. All of these suggest that blind occipital regions primarily become MD regions, and their activation during language tasks is limited to those that require domain-general cognitive control.