Face information processing in the left inferior temporal lobe: An ECoG case study

Abstract

Functional magnetic resonance imaging (fMRI) studies have identified that the human fusiform gyrus contains specialized regions for the processing of faces, often labeled as the fusiform face areas (FFA). However, fMRI, on its own, is a correlative measurement that cannot provide evidence for the causal role of FFA in face processing. Evidence for a causal role of FFA can be acquired by using a multimodal approach that combines fMRI, electrocorticogram, electronic brain stimulation, and behavior. The current study investigated the role of the left FFA in facial information processing by directly recording event-related potentials from the inferior temporal lobes with intracranial electrodes in a patient with suspected right temporal lobe epilepsy. Our results show that, faces induced stronger blood oxygenation level dependent and electrophysiological response at the left FFA compared to other image categories; electrical stimulation through the electrode placed at the left FFA did not produce self-reports of perceptual face distortion; but electrical stimulation to the left FFA did reduce sensitivity to subtle changes in facial contours. These results suggest that the left FFA may play a causal role in the fine processing of facial shape, and may have distinct functions from the corresponding area of the right hemisphere.