Neural correlates of covert word reading in hearing and deaf adults

The present study compared the neural correlates of covert reading in hearing and deaf adults proficient readers. Participants were asked to covertly read visually presented words or passively attend strings of consonants while being scanned with fMRI. Deaf participants preferentially using spoken Italian (Deaf-SI) and deaf participants preferentially using Italian Sign Language (Deaf-LIS) were also compared. Deaf-LIS showed activation of supramarginal gyrus and precentral regions of the left hemisphere, indicating greater reliance of articulatory component of speech during covert word reading. Compared with hearing participants, Deaf-LIS have higher activations of lingual and fusiform gyri, close to the Visual Word Form Area, suggested to be specialized for printed word recognition. Compared with Deaf-SI participants, Deaf-LIS showed de-activation of posterior cingulate cortex, suggesting greater attentional effort in covert reading. The current results confirm the presence of a cortical network shared by hearing and deaf participants with different communication mode when covertly read words. They also reveal differences in neural activity driven by auditory and linguistic experiences, pointing to a greater role of articulation of speech, lexical-orthographic processing and their corresponding neuronal resources for deaf using sign language.