Assessing the Utility of Regenerative Peripheral Nerve Interfaces (RPNIs) in Providing Referred Sensations in a Functional Task in a Virtual Environment

Individuals who use upper limb prostheses receive limited feedback from their devices. Researchers have attempted to elicit sensation through direct stimulation of peripheral nerves or through stimulation of reinnervated skin or muscle. Previous research found that electrical stimulation of Regenerative Peripheral Nerve Interfaces (RPNIs) elicited sensations that were referred to the phantom hand. The purpose of this study was to determine if this sensation could be used to improve performance of a functional task. Two participants with upper limb loss completed the Box and Blocks Test in a virtual environment under four feedback conditions on a single day of testing. These conditions included no feedback, vibration triggered by object contact, and two conditions where RPNIs were electrically stimulated upon object contact. For the RPNI conditions, one was non-somatotopic, meaning the RPNI sensation was referred to an area on the phantom hand and the other was somatotopic, where the referred sensation and virtual sensor were collocated. Participants moved more blocks with somatotopic feedback to a moderate effect. Both participants expressed a preference for the somatotopic sensation, noting that it made their movements feel more natural. Overall, this study demonstrates that RPNI-elicited sensation has the potential to improve performance in functional assessments.