Les visages et leurs émotions

Faces represent a crucial vector of interhuman communication. The message transmitted by the face has multiple features. Recognition of each feature can be impaired independently or in combination with others. In order to understand the behavioral consequences of such impairments, which can be a major social handicap, we first must specify the neural networks involved in face recognition. We propose in this first part to present the systems involved in face recognition, in particular the question of identity and prosopagnosia. Different neural networks are indeed implicated in the recognition of invariant facial features such as identity, gender, ethnicity, and recognition of variant features like facial expression and eye gaze. This paper is illustrated by some of our scalp and intracranial electrophysiological studies performed in humans allowing us to describe some aspects of face recognition dynamics combining an excellent spatial and temporal resolution. Intracranial recordings were performed in drug refractory epileptical patients implanted with depth electrodes. These studies demonstrate that numerous deep brain and cortical structures participate early and sometimes in a sustained manner in face recognition.