Cortical Response to Expectation of Tactile Stimulation from External Anthropomorphic and Non-Anthropomorphic Systems

Abstract

Complete sensorimotor integration and user acceptance of a neural prosthesis relies on system embodiment - the incorporation of an external system into one's own body schema and representation. Embodiment of neural prostheses is an ambiguous concept with limited approaches for quantifying human and machine integration in a meaningful way. In an attempt to understand human sensory integration with external systems, we measured neural activity in the somatosensory cortex of a participant with chronically implanted microelectrode arrays during sensory events tied to either a virtual robotic hand touching an object or a virtual lamp lighting up. Sensory stimulation was delivered using either skin vibration or intracortical microstimulation (ICMS) and was mapped to the virtual systems. Through the brain-machine interface, we observed quantifiable cortical activity corresponding to tactile sensations perceived during the virtual tasks and even during instances when neural stimulation was expected but not delivered, demonstrating the presence of sensory-related neural activity even in the absence of tactile stimulation. Evoked sensory expectation signals were also observed in the motor cortex, although at reduced amplitudes. Evoked cortical activity corresponding to expectation of a sensory input could serve as objective cortical markers for better understanding sensori-motor integration and perceptual experiences when connecting humans with external systems.