TACTILE EDGES AND MOTION VIA PATTERNED MICROSTIMULATION OF THE HUMAN CORTEX

Abstract

Intracortical microstimulation (ICMS) of somatosensory cortex evokes tactile sensations whose location and properties can be systematically manipulated by varying the electrode and stimulation parameters1–3. This phenomenon can be used to convey feedback from a brain-controlled bionic hand about object interactions. However, ICMS currently provides an impoverished sense of touch, limiting dexterous object manipulation and conscious experience of neuroprosthetic systems. Leveraging our understanding of how these sensory features are encoded in S14,5, we sought to expand the repertoire of ICMS-based artificial touch to provide information about the local geometry and motion of objects in individuals with paralysis. First, we simultaneously delivered ICMS through multiple, spatially patterned electrodes, adopting specific arrangements of aligned projected fields (PFs). Unprompted, the participants reported the sensation of an edge. Next, we created more complex PFs and found that participants could intuitively perceive arbitrary tactile shapes and skin indentation patterns. By delivering patterned ICMS sequentially through electrodes with spatially discontinuous PFs, we could even evoke sensations of motion across the skin, the direction and speed of which we were able to systematically manipulate. We conclude that appropriate spatiotemporal patterning of ICMS inspired by our understanding of tactile coding in S1 can evoke complex sensations. Our findings serve to push the boundaries of artificial touch, thereby enriching participants’ conscious sensory experience from simple artificial percepts to highly informative sensations that mimic natural touch.