A common neural basis for receptive and expressive communication of pleasant facial affect

There is accumulating evidence suggesting that the visual representation of facial affect is closely linked to its motor representation. To examine whether perception of pleasant facial affect involves neural circuitries associated with its production, we performed an fMRI experiment with 'compressed image acquisition' where subjects smiled and observed movies depicting other people smiling within scan-free time intervals between the acquisition of each image volume. Overlaps between the brain activation during observation and execution of smile expressions were located in the right premotor cortex and pars opercularis of the inferior frontal gyrus, right parietal operculum (SII) and left anterior insula. Observation of smile expressions further yielded signal increases within the posterior superior temporal sulcus (STS), fusiform gyrus and ventral amygdala. The results show that perceiving and expressing pleasant facial affect share a common neural basis in areas concerned with motor as well as somato- and limbic-sensory processing. In concert with temporal regions serving the visual analysis of facial expressive features, a mapping of the observed expressions onto neural circuitries associated with the production of these expressions and its somatosensory consequences could provide a description of what the expression would feel like if produced in the observer. Such a mechanism is suggested to be important for empathic understanding of others' feelings.