Face processing in the human amygdala at the single-neuron level.

The primate temporal cortex has a specialized system for representing faces, as borne out by a large literature from fMRI in humans and single-unit recordings in monkeys. Sophisticated computational models explain how population-level activity in this system represents the identity and familiarity of faces. But what happens next? How does the brain represent the social and emotional attributes of faces in regions that receive their input from temporal cortex? The most prominent structure for investigation here is the amygdala, but severe signal dropout and poor resolution greatly limits our knowledge from fMRI studies. Here we present data acquired from single-neuron recordings in human epilepsy patients. These data provide the first comprehensive inventory of face responses in the human amygdala during social trait judgement. Furthermore, they advance new models that incorporate the amygdala into a broader system for social cognition from faces.