Restored somatosensation in individuals with lower limb loss improves gait, speed perception, and motor adaptation

Lower limb loss is a significant insult to the body’s nervous and musculoskeletal systems. Despite technological advances in prosthesis design, artificial limbs are not yet integrated into the body’s physiological systems. Therefore, lower limb amputees (LLAs) experience lower balance confidence, higher fear of falls, and impaired gait mechanics compared to their able-bodied peers (ABs). Restoring sensations perceived as originating directly from the missing limb via implanted neural interfaces were shown to improve balance and performance in certain ambulatory tasks; however, the effects of such evoked sensations on neural circuitries involved in the locomotor activity are not well understood. In this work, we investigated the effects of plantar sensation elicited by peripheral nerve stimulation delivered by multi-contact nerve cuff electrodes on gait symmetry and stability, speed perception, and motor adaptation during walking. We found that restored plantar sensation increased stance time and propulsive force on the prosthetic side, improved gait symmetry, and yielded an enhanced perception of prosthetic limb movement. Most importantly, our results show the locomotor adaptation among LLAs with plantar sensation became similar to ABs. These findings suggest that our peripheral nerve-based approach to elicit plantar sensation directly affects central nervous pathways involved in locomotion and motor adaptation during walking. Our neuroprosthesis provided a unique model to investigate the role of somatosensation in the lower limb during walking and its effects on perceptual recalibration following a locomotor adaptation task. Furthermore, we demonstrated how plantar sensation in LLAs could effectively increase mobility, improve walking dynamics, and possibly reduce fall risks. One-Sentence Summary Neuroprosthesis stabilizes gait and improves speed perception and locomotor adaptation in individuals with lower limb loss.