Kouros Azar Award in Neural Engineering Research
Name: Suzhou Li
Title: "Sensory Neuroprosthesis Improves Recovery from Treadmill-Induced Trips."
Advisors: Ron Triolo and Hamid Charkhkar
Abstract. Over 50% of individuals with lower limb loss (idLLL) report a fear of falling and avoid daily activities, which are partly due to their lack of plantar sensation. Plantar sensation provides feedback about how our bodies are moving in space and is crucial for maintaining stability and preventing falls. Two idLLLs received a sensory neuroprosthesis (SNP) that provided direct somatosensory feedback, co-located with prosthesis foot-floor interactions, via electrical stimulation through an implanted nerve cuff electrode. Previous work has shown that the SNP does improve perception of limb speed and that it preserves the body’s spinal neural pathways which are important in maintaining stability, but it is still unknown the direct effect of the SNP on trip recovery and avoiding falls. In this study, participants walked on a treadmill at their preferred walking speed and received perturbations involving a brief increase in treadmill speed. Perturbations were initiated at heel strike and randomly delivered to intact and prosthetic sides with the SNP active or inactive. Kinematic data from a 16-camera motion capture system and data from force plates embedded in the treadmill were collected. With the SNP active, participants exhibited decreased peak trunk flexion angular velocities during recovery. This showed that the SNP improved the participants’ trunk control. For intact side perturbations, peak ground reaction force magnitude (GRFmag) on the prosthetic leg’s first recovery step increased with the SNP active, which approaches the response on the intact leg’s first recovery step following a prosthetic side perturbation. This more symmetric recovery following intact side perturbations suggest that participants are more confident in their prosthetic leg for recovery. For prosthetic side perturbations, peak GRFmag decreased with the SNP active, indicating that participants required less force to arrest their forward rotation. These results suggest that participants utilized sensory feedback from the SNP to improve their sensorimotor control of maintaining stability. In conclusion, restoring plantar sensation in idLLLs could lead to reduced risk of falling by improving recovery from trips.