Grants We Funded

Abstract

Project Summary: Sensation is important for interacting with the external environment, modulating movement, and incorporating body parts into one's body schema. Unfortunately, natural sensory feedback is difficult to emulate after major limb amputation. Though modern prosthetics have sensors to detect sensory stimuli, there remains no reliable way for the prosthetic to communicate to the user what it feels. The most common strategy for sensory feedback is to use electrical pulses via an electrode placed directly on a transected nerve. This leads to neural inflammation and non-selective activation of all fiber types in the nerve, resulting in unnatural and/or painful sensations. We developed the Composite Regenerative Peripheral Nerve Interface (C-RPNI) as a novel surgical strategy to facilitate naturalistic sensory signaling. A C-RPNI is a transected nerve implanted between a small piece of skin and muscle. Injured nerve fibers prefer to grow back to their respective original tissue types; thus, nerve fibers involved in delivering tactile sensory information grow into the skin piece and motor nerves grow into the muscle piece. This physically separates nerve fibers with sensory function from those with motor function, making it easier to selectively stimulate the fibers responsible for touch sensations. We have shown that electrical and mechanical stimulation of the C-RPNI skin component can elicit sensory neural responses. The objective of this study is to use the C-RPNI to facilitate naturalistic sensory feedback. The central hypothesis is that applying biologically relevant patterned signaling to the C-RPNI dermal component will result in specific activation of cutaneous sensory fibers and mimic natural neural signaling. The hypothesis will be tested by pursuing two specific aims in an animal model: 1) developing a strategy for communicating prosthetic sensor readouts to the C-RPNI using a well-established computational neuromorphic model to create patterned electrical stimulation that mimics neural activity of sensory afferents; and 2) evaluating the perceived sensation during neuromorphic stimulation of C-RPNI with neuroimaging. This study will provide preclinical scientific evidence for translating the C-RPNI into humans with limb loss for the purpose of restoring naturalistic sensory feedback. This will enhance the quality of life and functionality for individuals with amputations. The C-RPNI has the potential to truly revolutionize prosthetic rehabilitation.

Impact Statement: The Composite Regenerative Peripheral Nerve Interface (C-RPNI) can isolate sensory nerve fibers responsible for touch sensation from other nerve fiber types after nerve transection in limb amputations. When combined with patterned electrical stimulation that mimics natural neural signaling patterns, the C-RPNI has the potential to facilitate naturalistic sensory feedback due to specific activation of the isolated touch sensory fibers. Natural sensory restoration will allow patients to feel what their prosthetic feels, modulate prosthetic movements, and improve prosthetic embodiment, all of which enhances the quality of life and functionality for individuals with amputations. The C-RPNI has the potential to truly revolutionize sensory restoration in prosthetic rehabilitation.

Biography
Widya Adidharma, MD completed her Bachelors of Science in Neuroscience and Human Biology from Michigan State University College of Natural Science on a full-ride merit scholarship and graduated with high honors. She obtained her Medical Degree from the University of Washington School of Medicine and was inducted into the Alpha Omega Alpha honor medical society. Throughout her undergraduate and medical school years, she won a number of research scholarships, published several peer-reviewed manuscripts and presented at multiple national conferences. She returned to Michigan for her residency in Plastic and Reconstructive Surgery at the University of Michigan. She has since joined the Neuromuscular Laboratory, where she will complete her research academic development time. She recently won a PSF Pilot Grant for her work in the Dermal Sensory Regenerative Peripheral Nerve Interface (DS-RPNI) and is co-editor of the upcoming 3rd edition of the textbook, Michigan Manual of Plastic Surgery. Dr. Adidharma combines her background in neuroscience and clinical training in plastic surgery to develop and lead translational projects in peripheral nerve injury.