Grants Funded

Abstract

Impact Statement: Extremity amputation affects over 185,000 individuals in the United States annually and has debilitating functional consequences. Although modern prostheses enable advanced movement, they are limited by poor sensory feedback, which contributes to prosthetic abandonment. A barrier to progress is the lack of patient-prosthetic interface that conveys prosthetic sensor data into neural signals for meaningful sensory feedback. The dermal sensory interface (DSI) is an impactful development because it is a novel biotic-abiotic biological interface that regenerating sensory nerves reinnervate. This provides a means for modality-matched afferent signaling, which contributes to the recovery of natural sensory feedback important for interacting with the environment and coordinated prosthetic control.

Project Summary: Providing prosthetic limbs with sensory feedback is critical for natural prosthetic control and interacting with the natural environment. Though advancements in prosthetic sensing capabilities have been made, restoration of sensory function after amputation remains a challenge due to the lack of a reliable patient-prosthetic interface. The Dermal Sensory Interface (DSI), composed of a de-epithelialized dermal graft secured around a transected sensory nerve, is a novel surgical technique developed to overcome this barrier. Our long-term goal is to develop a biologic neural interface capable of transducing sensory information from prostheses to afferent neural signal, thereby restoring sensation and paving the way for sensorimotor prosthetic control. Our previous research demonstrated that resected peripheral afferents can regenerate into DSIs, and that electrical and mechanical stimulation of DSIs can elicit graded afferent neural responses. The overall objective of this current study is to characterize the somatotopic map of DSI constructs and determine the range of sensory modalities that can be elicited with stimulation of DSIs. The central hypothesis is that regenerating afferents reinnervate available sensory end organs in the DSI, thereby re-establishing functional connections that allows for modality-matched and somatotopically organized sensory feedback. This hypothesis will be tested by pursuing the following two specific aims: 1) Determine the sensory modalities that can be elicited with stimulation of DSI constructs, and; 2) Characterize the somatotopic map of the DSI construct. In the first aim, we will assess in vivo sensory signals obtained during mechanical, thermal, and nociceptive stimulation of DSIs. Results will be compared to two controls: 1) stimulation of skin in the sural nerve receptive field, and; 2) acellular dermal matrix wrapped around transected sensory nerves. With the second aim, we will utilize immunohistochemistry and three-dimensional imaging to characterize the organization of sensory end organs and afferents in the DSI construct. We will further assess the reinnervation pattern among afferents. The DSI is innovative because it is a novel biotic-abiotic neural interface that allows for transduction of sensory stimuli into neural signals. The proposed research is significant because the results are expected to advance the restoration of natural sensation and development of sensorimotor control in prosthetic systems.

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.