Electrocorticography reveals the dynamics of famous voice responses in human fusiform gyrus

Voice and face processing occur through convergent neural systems that facilitate speaker recognition. Neuroimaging studies suggest that familiar voice processing engages early visual cortex, including the bilateral fusiform gyri (FG) on the basal temporal lobe. However, what role the FG plays in familiar voice processing and whether it is driven by bottom-up or top-down mechanisms is unresolved. In this study we directly examined neural responses to familiar voices and faces in human FG using direct cortical recordings in epilepsy surgery patients. We tested the hypothesis that neural populations in human FG respond to familiar voices and investigated the temporal properties of voice responses in FG. Recordings were acquired from five adult epilepsy surgery patients during a person identification task using visual and auditory stimuli from famous speakers (U.S. presidents Barack Obama, George W. Bush, and Bill Clinton). Patients were presented with images of presidents or clips of their voices and asked to identify the portrait/speaker. Our results demonstrate that a subset of face responsive sites in and near FG also exhibit voice responses that are both lower in magnitude and relatively delayed (300-600 ms) relative to visual responses. The dynamics of voice responses revealed by direct cortical recordings suggests a top-down feedback-mediated response to familiar voices in FG that may facilitate speaker identification.