Merged Haptic Sensation in the Hand during Concurrent Non-Invasive Proximal Nerve Stimulation

When individuals interact with the environment, sensory feedback is a critical aspect of the experience. Individuals using prosthesis often have difficulty controlling their device, partly due to a lack of sensory information. Transcutaneous nerve stimulation has the potential to elicit focal haptic sensation when controlled electrical current was delivered to a pair of electrodes in proximity to the nerve. The objective of this preliminary study was to evaluate how different elicited focal haptic sensation were altered, when multiple concurrent electrical stimuli were delivered to different portions of the median and ulnar nerve bundles. The delay between the individual stimulation during concurrent stimuli was also varied to identify if this parameter could alter the resulting sensation region. Lastly, the stability/repeatability of the perceived sensation during concurrent stimuli was determined. Our preliminary results showed that the spatial distribution of the haptic sensation was largely a direct summation/merge of the sensation regions from the individual nerve stimulation when comparing the regions to that of the concurrent double stimulation. Our results also showed that merged sensation region was not sensitive to different time delays the two concurrent stimuli. Lastly, the sensation regions remained stable and showed repeatable sensation in the hand even with 20-60 minutes between repeated stimulations.