NEC Seminar:
Speaker: Roberto Peralta
Advisor: Dr. Emily Graczyk
Abstract: Restoring touch after limb loss is critical for dexterous prosthesis control and psychosocial well-being. Although peripheral nerve stimulation (PNS) has been shown to evoke sensation in the missing limb, it often elicits unnatural, paresthetic percepts. The unnaturalness of stimulation-evoked sensation is believed to arise from the synchronous response of afferents to PNS. Stimulation paradigms which leverage asynchronous recruitment may improve quality of PNS-evoked sensation. Herein, we evaluate BioS – a novel, high-frequency, pulse amplitude-modulated approach designed to promote asynchronous, biomimetic activation of afferents. Gradually ramping the pulse amplitude expands the targeted population, while the sub-refractory stimulus period reduces the likelihood of recruiting each axon with each pulse – together producing more stochastic afferent activity. Three subjects with upper limb amputation and one subject with sensory incomplete spinal cord injury were implanted with 16-contact Composite Flat Interface Nerve Electrodes (C-FINEs). BioS trains were delivered at 20 Hz with a 0.7 duty cycle, and pulse amplitude or pulse width was ramped from threshold to a mid-comfortable level. All stimuli were intensity-matched and delivered in pseudorandom order. The participant rated sensation qualities on visual analog scales. Ratings were normalized to block means and combined across blocks. BioS was found to significantly improve the naturalness of evoked sensations and reduce paresthetic qualities. These results highlight BioS as a promising approach to improve the naturalness of PNS. Further investigation and clinical implementation is needed to evaluate its effects on psychosocial wellbeing and function.