Mapping face- and house-selectivity in ventral occipito-temporal cortex with intracerebral potentials.

Abstract

Categorization of visual entities is thought to be supported by distinct neuronal populations in the human ventral occipito-temporal cortex (VOTC). Here we report a global mapping of the VOTC for selective responses to faces and houses with intracerebral EEG in a large population of human subjects (N=70). Participants viewed variable objects images presented periodically at 6 Hz with either variable face or house images interleaved as every 5th image (in separate sequences). Face-and house-selective responses were objectively quantified at the face or house stimulation frequency (6Hz/5=1.2 Hz) and harmonics. House- and face-selective contacts were spatially organized along the medial-to-lateral axis, respectively, consistent with neuroimaging studies (Fig.1). Importantly, both types of contacts, with a higher proportion for face-than house-selective sites, were found in the anterior temporal lobe (ATL), a region contaminated by large artifacts in neuroimaging (Fig. 2, top). Moreover, in the ATL we found a substantial portion of face- or house-exclusive contacts that showed no response for other objects at 6 Hz (Fig. 2, bottom). Finally, at “overlap” contacts responding to both faces and houses, the amplitudes to faces and houses correlated weakly (Fig. 3), indicating that these contacts also measure at least partly dissociated face- and house-responses. Thus, overall, the results suggest that both posterior and anterior portions of the VOTC contains distinct and distributed neuronal populations dedicated to recognition of face- and landmark-stimuli.