A Context-Dependent Switch From Sensing to Feeling in the Primate Amygdala

Abstract

SUMMARYThe skin transmits affective signals that are fully integrated into our social vocabulary. As the socio-affective aspects of touch are likely processed in the amygdala, we compared neural responses in the amygdala and primary somatosensory cortex of non-human primates to social grooming and gentle airflow stimuli. As expected, neurons in the primary somatosensory cortex responded to both types of tactile stimuli. In the amygdala, however, neurons did not respond to individual grooming sweeps even though grooming elicited autonomic states indicative of positive affect. Instead, neurons in the amygdala showed sustained changes in baseline firing rates during periods of grooming relative to airflow stimulation, that reliably encode the social or non-social context. These observations suggest that during social and affective touch the amygdala switches from processing external inputs on short time scales to processing social context and the associated affective states on longer time scales.

Keywords: tactile, social, baseline, somatosensory cortex, non-human primate, gating