VTHand-centred space · Visuo-tactile cortical mechanims for a hand-centred spatial representation in humans

When interacting with objects the brain needs to locate the limbs and the relevant visual information surrounding them. Studies on monkeys showed that information from different sensory modalities converges at the individual neurone level within a multisensory fronto-parietal network. This multisensory integration occurs within the space surrounding the body (peripersonal space) and has been linked to the sensory guidance of reaching and defensive movements, and localisation the limbs in space. In humans, only indirect behavioural evidence exists of a similar representation, and virtually nothing is known about the neuronal mechanisms of multisensory integration in peripersonal space.This project will provide the first direct evidence for the existence of an integrative visuo-tactile (VT) mechanism in the human brain by identifying the areas which implement it in hand-centred coordinates. We will use an innovative multimodal strategy involving complementary behavioural, functional magnetic resonance imaging (fMRI) and transcranial stimulation (TMS) approaches. We mean to employ cross-modal fMRI-adaptation to identify neuronal responses reflecting the multisensory integrative mechanisms of the VT peri-hand space representation. This method allows us to circumvent the limits of traditional fMRI analysis and go beyond the voxel-level resolution. We will investigate the plasticity of the VT peri-hand space during tool use and when prosthetic limbs are experienced as one’s own body part. Finally, TMS will reveal the link between the plasticity of the multisensory space representation and the motor system.This project has important clinical and industrial applications. Understanding the rapid plasticity of the multisensory peripersonal space will help to develop new rehabilitative strategies for amputees using advanced prosthetic limb devices. Our work will be important for optimising the control of virtual and robotic tools during fine manipulation (i.e. tele-surgery).