Keywords

Neuromodulation, Non-Invasive Stimulation, EEG Data, Sensory Restoration, Transcutaneous Electrical Nerve Stimulation, Naturalistic Sensations

Abstract

This study investigates the relationship between electrical stimulus characteristics of shape and charge on evoked sensations and electroencephalogram (EEG) data during multi-waveform transcutaneous electrical nerve stimulation (TENS) of the median nerve. Neuromodulation methods have traditionally had little control over the location and quality of their associated evoked sensation (e.g., electric, vibration, touch). This experiment utilized five unique stimulus waveforms during TENS stimulation. EEG data were collected concurrently to provide an introductory objective measure of the neural responses underlying these sensory changes. Eleven participants completed three tasks (thresholding, super-threshold stimulation, two-alternative forced choice) using a two-electrode TENS approach. Stimulus waveforms were able to evoke sensations at notably different threshold charges and evoke significantly different intensities of sensation across notably different areas of the hand. Charge was found to have a complementary relationship with the evoked sensation’s area and intensity across all waveforms. At threshold, the sine waveform evoked the most intense sensation over the largest area out of the five waveforms. Waveforms presented unique rates of recruitment between sensation categories, although unnatural pulse and electric sensations presented the highest rates across all waveforms. EEG data revealed significant differences in SEP amplitudes between waveforms at N140, P200, and P300, suggesting that the specific waveform shapes of sine and square, alongside charge, correlate with a higher amplitude of neural activity when compared to the triangular waveforms. A two-alternative forced-choice task showed that participants could accurately distinguish between waveforms (83.5%), even while reporting large differences in their subjective experiences. The findings highlight the importance of the temporal characteristics of stimulus waveforms, as most participants (90%) preferred non-square waveforms. The subjective findings suggest that triangular waveforms offer optimal temporal parameters for evoking preferred sensations closer to touch, whereas square and sine waveforms consistently evoke intense sensations over larger areas of the hand.

Thesis Completion Year

2026

Thesis Completion Semester

Summer

Thesis Chair

Rakhshan, Mohsen

College

College of Engineering and Computer Science

Department

Department of Electrical and Computer Engineering

Thesis Discipline

Electrical Engineering

Language

English

Access Status

Open Access

Length of Campus Access

None

Campus Location

Orlando (Main) Campus

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