Brain Activation Measurement of Velvet Hand Illusion Using Pocket NIRS

In this research, as a different approach to the conventional one which enhances the performance with hardware of a haptic device, we adopt another approach to make the brain feel as if the person is touching the real thing via an illusion. Thus, we study Velvet Hand Illusion (VHI) which is an illusionary phenomenon concerning tactile touch. In VHI, a hexagonal wire mesh is sandwiched between both hands and rubbing the wire mesh without relative motion between both hands generates a smooth feeling, like velvet. The brain activation at this time is measured by PocketNIRS, which contains two channels measuring the bilateral prefrontal cortex. We obtained the result that the prefrontal cortex was activated to roughly two times larger when VHI occurred than when touching real velvet fabric. Since different responses can be obtained in the prefrontal cortex during brain activation between real velvet and VHI, it is possible to use pocketNIRS for the evaluation of VHI.