Sensory percepts induced by microwire array and DBS microstimulation in human sensory thalamus

摘要

Abstract Background Microstimulation in human sensory thalamus (ventrocaudal, VC) results in focal sensory percepts in the hand and arm which may provide an alternative target site (to somatosensory cortex) for the input of prosthetic sensory information. Sensory feedback to facilitate motor function may require simultaneous or timed responses across separate digits to recreate perceptions of slip as well as encoding of intensity variations in pressure or touch. Objectives To determine the feasibility of evoking sensory percepts on separate digits with variable intensity through either a microwire array or deep brain stimulation (DBS) electrode, recreating “natural” and scalable percepts relating to the arm and hand. Methods We compared microstimulation within ventrocaudal sensory thalamus through either a 16-channel microwire array (～400?k? per channel) or a 4-channel DBS electrode (～1.2?k? per contact) for percept location, size, intensity, and quality sensation, during thalamic DBS electrode placement in patients with essential tremor. Results Percepts in small hand or finger regions were evoked by microstimulation through individual microwires and in 5/6 patients sensation on different digits could be perceived from stimulation through separate microwires. Microstimulation through DBS electrode contacts evoked sensations over larger areas in 5/5 patients, and the apparent intensity of the perceived response could be modulated with stimulation amplitude. The perceived naturalness of the sensation depended both on the pattern of stimulation as well as intensity of the stimulation. Conclusions Producing consistent evoked perceptions across separate digits within sensory thalamus is a feasible concept and a compact alternative to somatosensory cortex microstimulation for prosthetic sensory feedback. This approach will require a multi-element low impedance electrode with a sufficient stimulation range to evoke variable intensities of perception and a predictable spread of contacts to engage separate digits. Highlights ? Human thalamic microstimulation simulates input of prosthetic sensory data. ? Stimulation through microwire and DBS electrodes replicate hand and finger percepts. ? Patterning of stimuli alters the naturalness of the evoked percept. ? Intensity encoding is possible but with reduced naturalness. ? Limitations include defining specific percept location and duration of stimuli.