Non-rectangular neurostimulation waveforms elicit varied sensation quality and perceptive fields on the hand

Abstract

Electrical stimulation of the nerves is known to elicit distinct sensations perceived in distal parts of the body. The stimulation is typically modulated in current with charge-balanced rectangular shapes that, although easily generated by stimulators available on the market, are not able to cover the entire range of somatosensory experiences from daily life. In this regard, we have investigated the effect of electrical neurostimulation with four non-rectangular waveforms in an experiment involving 11 healthy able-bodied subjects. Weiss curves were estimated and rheobase and chronaxie values were obtained showing increases in stimulation time required to elicit sensations for some waveforms. The localization of the sensations reported in the hand also appeared to differ between waveforms, although the total area did not vary significantly. Finally, the possibility of distinguishing different charge- and amplitude-matched stimuli was demonstrated through a two-alternative-forced-choice (2AFC) match-to-sample task, showing the ability of participants to successfully distinguish between waveforms with similar electrical characteristics but different shapes and charge transfer rates. This study provides evidence that, by using different waveforms to stimulate nerves, it is possible to affect not only the required charge to elicit sensations but also the sensation quality and its localization.

Wrist Posture Unpredictably Affects the Perception of Transcutaneous Electrical Nerve Stimulation

“…Participants reported the tactile percepts as originating distally in their hand rather than in the skin below the electrodes, indicating that our TENS approach was indeed targeted and stimulated underlying sensory fibers that innervated the hand. Consistent with prior studies, TENS was most commonly described as feeling like pins and needles, buzzing, and/or pulsing (12–14). As wrist posture changed, there were minor changes in sensation quality for half of the participants, substantial percept location changes for 11/12 participants, and no major change in percept size for any participants.…”

“…The data points collected during threshold testing were fit to a strength-duration curve using Lapicque’s equation ( Equation 1 ) (11,12,17–19). Lapicque’s equation was fit to the raw data using a nonlinear least-squares method with bisquare weighting, with starting values of b=0.1 and c=1000.…”

“…TENS electrodes placed on the forearm (9), biceps (10), elbow (11), or wrist (12) have successfully elicited tactile sensations in the hands of able-bodied individuals. TENS has been described as feeling like tingling, vibration, pulsing, fluttering, tapping, electricity, or touch (12–14).…”

“…TENS electrodes placed on the forearm (9), biceps (10), elbow (11), or wrist (12) have successfully elicited tactile sensations in the hands of able-bodied individuals. TENS has been described as feeling like tingling, vibration, pulsing, fluttering, tapping, electricity, or touch (12–14). The perception of TENS obeys a strength-duration curve, in which perception is governed by an inverse relationship between pulse amplitude and pulse width/duration (11,12).…”

“…TENS has been described as feeling like tingling, vibration, pulsing, fluttering, tapping, electricity, or touch (12–14). The perception of TENS obeys a strength-duration curve, in which perception is governed by an inverse relationship between pulse amplitude and pulse width/duration (11,12). As pulse amplitude increases, the pulse width needed to maintain detection of the stimulus decreases.…”