A Virtual Reality Environment for Testing Somatosensory Neuro- Prostheses

INTRODUCTION The sense of touch plays a crucial role in our everyday lives. Touch allows us fine motor control, adds to our sense of self, and helps with our perception of the world around us [3]. Without it, accomplishing simple everyday tasks would become overwhelmingly difficult. Such is the life of approximately two million amputees in the United States today [2]. In order to improve the lives of amputees, advancements have been made allowing the prosthetics to interface with the subject’s brain. This neural link allows the subject to move the prosthetic device through the sheer power of their mind [3]. As a result the prosthetic begins to feel more natural to the amputee. But without sensory feedback, the subject still experiences difficulties in fine motor control and pain which appears to emanate from the missing limb [3]. During recent experiments at the Human Rehabilitation and Neural Engineering Laboratory (hRNEL), we have demonstrated it is possible to generate sensations which appear to emanate from a missing limb. In order to create these sensations, a subject must be implanted with an array of electrodes along their cervical spinal nerves. By electrically stimulating these electrodes, the subject begins to feel sensations originating from the location of their missing limb. Ideally if these sensations are incorporated with the prosthetic, the amputee’s will see improvements in fine motor control, and a reduction in pain. But these sensation are not ideal. In fact more often than not, they are accompanied by an unnatural buzzing feeling known as paresthesia [3]. Another issue is that the location of the produced sensations is not always exactly where it was intended to be. Combining both problems causes an unnatural feel which takes away from the benefits of sensory feedback restoration. Therefore in order to help amputees, we need to discover a way to improve the naturalness of the sensations generated through electrical stimulation.