Seeing to Feel: From Sensorimotor to Social Aspects of Peripersonal Space
Alessandro Farne (Lyon)
Date: Thursday 27 November 2014 5:00 pm - 7:00 pm Venue: Senate House, Senate House, WC1E 7HU
Commentator: Chiara Brozzo (Antwerp)
The binding of visual information available outside the body with tactile information arising from the body surface allows for the representation of the space lying in between, which is often the theatre of our interactions with objects. The definition of what has become known as “peripersonal space”, originates from single-unit electrophysiological studies in monkeys, based on a class of multisensory, predominantly visual–tactile neurons. Such neurons, identified in several parietal and premotor regions of the monkey brain, respond both to visual and tactile stimuli, their visually evoked responses being stronger when objects are closer to the tactile receptive field. Thus, visual information is coded as ‘tactile’ in advance to the contact with the body (e.g., with hands), in a body-part centred reference frame.
Today, I will first recall the behavioural and functional neuroimaging evidence that suggested the existence of a similar representation of the peripersonal space in humans, based upon a network of posterior parietal and premotor areas. I’ll present results indicating that, similar to non-human primates, the peri-hand space in humans is represented in hand-centred coordinates. My focus will then be on this question: what is the function of such a multisensory system? I will provide behavioural and electrophysiological evidence for its role in the planning and execution of both defensive (avoidance) and appetitive (reach-to-grasp) actions on nearby objects. This evidence demonstrates how multi-sensory-motor systems may process hand-related visual inputs within just 70 ms following a sudden event, and before the execution of a grasping action. I’ll then present data showing that other people’s actions can induce in the observer not only a motor resonance, but also a resonance of the multisensory perceptual consequences of the observed action. Intriguingly, this effect appears dependent on the observer’s prior actual experience, suggesting a differential role for enacted vs. merely potential actions in the subject’s sensorimotor repertoire.
Overall, previous and on-going work in our laboratory indicate that performing actions induce a fast remapping of the multisensory peripersonal space, as a function of on-line sensorimotor requirements, thus supporting the hypothesis of a role for peripersonal space in the generation and control of rapid hand-centred avoidance and acquisitive actions.
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