Close to me: Behavioural and electrophysiological investigations of peripersonal space

To facilitate everyday interactions with a complex world, our brain constructs distinct representations of the space surrounding our body. Processing of (multi)sensory information arising from the space within reach of the body (peripersonal space, PPS) is enhanced to facilitate both the rapid detection of potential threats to the body and the execution of actions towards reachable objects. Despite the increasing number of studies aimed at investigating PPS, fundamental questions still remain unanswered. In this talk, I will present two studies investigating plasticity and individual differences in PPS. First, I will discuss electrophysiological evidence suggesting that plastic changes to PPS induced by the active use of long tools modulate directly to brain activity in early somatosensory areas. Results revealed increased multisensory integration of stimuli presented at the tip of the tool, supporting the hypothesis that the representation of space surrounding the hand is extended by tool use. Second, I will present a study investigating the links between PPS and empathy. Although PPS has been defined as the space within which goal-oriented actions are executed, it provides the setting for interactions with other human beings. Empathy is fundamental for such inter-personal interactions and existing evidence suggests that the empathic responses to emotional stimuli depend on the physical distance between emotional stimuli and the observer.  We tested the hypothesis that the strength and size of PPS representations are linked to empathy. Results revealed an inverse relationship between empathy and PPS with highly emphatic individuals showing weaker representations of PPS. We speculate that highly empathic individuals might be better at evaluating others’ emotions thanks to their PPS plasticity which allows them to share their personal space with other individuals and incorporating others within their own PPS representations.