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Speaker: Bronwyn Spilker
Advisor: Dr. Emily Graczyk

Abstract: Peripheral nerve stimulation (PNS) and intracortical microstimulation (ICMS) can restore tactile sensation to people living with sensory deficits due to spinal cord injury (SCI) or amputation. In the Reconnecting the Hand and Arm to the Brain (ReHAB) clinical trial, PNS and ICMS can be implemented in the same system and even at the same time. Co-application of PNS with ICMS may allow us to probe how peripheral inputs interact with neural activity in cortical circuits, and could result in more complex or nuanced sensory percepts than either approach individually. The goal of this study was to investigate how ICMS- and PNS- evoked percepts integrate, and what effects the relative stimulation onset timing will have on the sensory experience. In experiment 1, the point of subjective simultaneity indicated that ICMS should be applied 61 ms before PNS to be perceived as maximally simultaneous. In experiment 2, the perceived naturalness ratings were significantly greater for conditions when ICMS was applied, and the perceived intensity was greater when PNS was applied. This study provides new knowledge about how stimulation applied simultaneously at different levels of the somatosensory pathway interact and modulate the evoked sensory experience. These findings lay the foundation for the development of novel neurostimulation strategies for sensory restoration.