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Simultaneous modulation of pulse charge and burst period elicits two differentiable referred sensations

Benigni, Tommaso1; Pena, Andres1; Kuntaegowdanahalli, Sathyakumar1; Abbas, James1; Jung, Ranu1

Research facility: The Institute for Integrative & Innovative Research (I³R) at University of Arkansas
Published Sep 12, 2024 on Dryad. https://doi.org/10.5061/dryad.5hqbzkhdx

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Sep 12, 2024 version files 928.80 KB

Abstract

Objective. To investigate the feasibility of delivering multidimensional feedback using a single channel of peripheral nerve stimulation by complementing percepts of intensity with percepts of flutter frequency controlled by burst period modulation.

Approach. Two dimensions of a distally referred sensation were provided simultaneously: intensity was conveyed by the modulation of the pulse charge rate inside short discrete periods of stimulation referred to as bursts, and frequency was conveyed by the modulation of the period between bursts. For this approach to be feasible, intensity percepts must be perceived independently of frequency percepts. Two experiments investigated these interactions. A series of two alternative forced choice tasks (2AFC) were used to investigate burst period modulation's role in intensity discernibility. Magnitude estimation tasks were used to determine any interactions in the gradation between these frequency and intensity percepts.

Main Results. The 2AFC revealed that burst periods can be individually differentiated as a gradable frequency percept in peripheral nerve stimulation. Participants could correctly rate a perceptual scale of intensity and frequency regardless of the value of the second, but the dependence of frequency differentiability on charge rate indicates that frequency was harder to detect with weaker intensity percepts. The same was not observed in intensity differentiability as the length of burst periods did not significantly alter intensity differentiation. These results suggest that multidimensional encoding is a promising approach for increasing information throughput in sensory feedback systems as long as intensity ranges are selected properly.

Significance. This study provides valuable insights into haptic feedback through the peripheral nervous system and demonstrates an encoding approach that may offer enhanced information transfer for use in virtual reality applications and in sensory-enabled prosthetic systems. The feasibility of the multidimensional encoding approach in performing control tasks opens new avenues for developing enriched sensory feedback systems.