Sensorimotor Network in Social Cognition

Our motor and somatosensory cortices originally evolved to control our movement through the environment. In the past decade, one of the most exciting developments in cognitive neuroscience is the discovery that the same sensorimotor brain regions that are used to control our body are involved in the perception of others’ actions, sensations and emotions. Human beings are equipped with a mechanism mapping perceptual representations of actions, sensations, and emotions onto sensorimotor representations, thus, perception of others might be inherently grounded in the same brain regions involved in first-hand subjective experiences. While the notion that observing, or imagining actions, emotions, and sensations in others triggers vicarious activations in the sensorimotor network is widely accepted, evidence about the specific role of these activations in social cognition is meagre and still largely based on correlational data. The experiments included in the present thesis aim at exploring the functional role of the sensorimotor network in understanding others’ internal emotional and cognitive states. We used neuromodulation tools to interfere with brain activity in regions involved in moving and sensing the body while participants were asked to understand others’ emotions or intentions. In experiment 1 to 7 we focused on the ability to accurately understand amusement from observed smiles, while in experiment 8 to 10 we explored the ability to rate the pain felt by another individual when her/his experience is described only through text. Our results show that interference with activity within somatosensory and motor cortices impairs participants’ ability to understand others’ emotions. Combining complex naturalistic tasks to neuromodulation tools, the present thesis sheds novel light on the behavioural relevance of vicarious activations in the sensorimotor network, by establishing a strong and direct causal link between sensorimotor brain networks and others’ understanding that was only suggested in the past.