Velocity ratings and perceptual qualities of electrotactile stimulation of the foot sole are impacted by direction, stimulus interval, and cutaneous saltation.

Abstract

Electrotactile stimulation is a çmethod of activating the tactile system by bypassing cutaneous mechanoreceptors and exciting the cutaneous afferent endings directly. This method is of interest for its potential in wearable tactile augmentation technologies. The generation of meaningful electrotactile sensation could benefit cases of peripheral neuropathy or prosthesis. There are limitations in our understanding of an electrotactile stimulations' capacity to represent tactile sensibilities, and its susceptibility to missense. The spatiotemporal parameters of an electrotactile sequence were varied. The present work extends the assessment of subjective evaluations of localization, velocity, and descriptive qualities. We applied electrotactile pulses at three sites on the foot sole, using three patterns across these sites: toward the heel or toes. We tested at three interstimulus intervals (100 ms, 160 ms, 220 ms). Faster sequences produced higher velocity ratings. Sequence direction across the foot sole impacted velocity ratings-with heel-to-toe sequences demonstrating a higher velocity rating than toe-to-heel sequences. During faster sequences with site repetition, cutaneous saltation is likely causing missense during localization. The spatiotemporal missense did not impact velocity ratings. This indicates that certain aspects of electrotactile sequence perception, such as velocity, are preserved through tactile illusions. These findings may be used to increase the resolution of stimulating grids.