Dissociable neural pathways for the perception and recognition of expressive and instrumental gestures

Previous functional imaging studies have sought to characterize the neural correlates of gesture representation. However, little is yet known about the representation of different categories of gesture. Here we contrasted the perception of hand gestures that express inner feeling states, e.g. I am angry, I do not care, with the perception of instrumental gestures intended to change the behavior of others by communicating commands, e.g. come here, look over there. We hypothesised that recognition of expressive gestures would activate a network of brain regions associated with mentalising ('theory of mind') whereas instrumental gestures would activate different neural pathways. Twelve normal volunteers underwent fMRI while they watched a series of short videos (3 s duration) of actors performing expressive and instrumental gestures. The volunteers had either to recognise the gesture or to monitor the positions of the hands. As predicted, different neural networks were activated by the observation of instrumental or expressive gestures. The perception of expressive gestures elicited activity in the anterior paracingulate cortex, the amygdala and the temporal poles bilaterally and the right superior temporal sulcus. These regions have all previously been activated during the performance of mentalising tasks. In contrast, instrumental gestures elicited activity in a left-lateralised system previously associated with language and motor imitation.