Quantifying the spatial stability of sensory stimulation projected fields for sensory neuroprostheses

PROJECT SUMMARY This research is motivated by the goal of improving the lives of individuals with sensorimotor deficits through somatosensory feedback. Recent neuroprostheses development has demonstrated providing sensory feedback improves the control of neuroprosthetic devices. The technological and clinical development is approaching long-term investigations for ultimate translation to independent home use of a neuroprosthesis. As such, a growing number of studies suggest that the projected fields (PFs), the locations of perceived sensations through stimulation, are relatively consistent over the study period. However, there has been little focus on determining the spatial stability of the PFs. Spatial stability is important because knowing where percepts occur will be critical for designing somatosensory neuroprostheses that can be used in daily life without the need for regular recalibration of the stimulation. My goal is to develop a quantitative approach to determine the spatial stability of sensory stimulation PFs. By establishing an understanding of how PFs are spatially preserved over time, I envisage the quantitative framework to bridge the intuition of PF stability and the experimental data collected from sensory stimulation experiments. I will leverage PF data obtained from two different electrical stimulation techniques and determine the co-occurrence between PFs, their spatial contiguity, and investigate functionally relevant PFs. Aim 1 will determine the co-occurrence and spatial contiguity of PFs. I will develop new algorithms that take into consideration the overall activation frequency of each PF, its co-occurrence with other PFs, and the spatial contiguity. To determine the statistical significance, I will use a statistical null model that sets a benchmark of “by-chance” level stability. The statistical null model will be determined through binomial process simulations. Aim 2 will determine the spatial stability of functionally relevant PFs. Functional relevance is important because a critical goal for somatosensory neuroprostheses is to provide reliable somatosensory feedback and enable independent home use for daily tasks. In this aim, I will determine regions of the hand that are important for different prosthesis grips used in functional tasks. I will then compute the co-occurrence of these functionally relevant regions and determine their spatial stability. Fundamentally, Aim 1 focuses on PF spatial stability from empirical data regardless of sensory stimulation techniques, while Aim 2 focuses on PF spatial stability for functional relevant regions. When completed, this work will be applicable to all somatosensory neuroprostheses development in which ensuring PF spatial stability is crucial to establish long-term somatosensory feedback for independent home use.