Proportional sway-based electrotactile feedback improves lateral standing balance

V S Raghav Hari Krishna; Jeonghee Kim; Shuo-Hsiu Chang; Yoonsuck Choe; Hangue Park

doi:10.3389/fnins.2024.1249783

Proportional sway-based electrotactile feedback improves lateral standing balance

Front Neurosci. 2024 Mar 18:18:1249783. doi: 10.3389/fnins.2024.1249783. eCollection 2024.

Authors

V S Raghav Hari Krishna¹, Jeonghee Kim², Shuo-Hsiu Chang³, Yoonsuck Choe¹, Hangue Park^{4

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Affiliations

¹ Department of Computer Science and Engineering, Texas A&M University, College Station, TX, United States.
² Department of Electronic Engineering, Department of Biomedical Engineering, and Department of Artificial Intelligence, Hanyang University, Seoul, Republic of Korea.
³ Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston, Houston, TX, United States.
⁴ Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea.
⁵ Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, Republic of Korea.
⁶ Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, United States.

Abstract

Introduction: Plantar cutaneous augmentation is a promising approach in balance rehabilitation by enhancing motion-dependent sensory feedback. The effect of plantar cutaneous augmentation on balance has been mainly investigated in its passive form (e.g., textured insole) or on lower-limb amputees. In this study, we tested the effect of plantar cutaneous augmentation on balance in its active form (i.e., electrical stimulation) for individuals with intact limbs.

Methods: Ten healthy subjects participated in the study and were instructed to maintain their balance as long as possible on the balance board, with or without electrotactile feedback evoked on the medial side of the heel, synched with the lateral board sway. Electrotactile feedback was given in two different modes: 1) Discrete-mode E-stim as the stimulation on/off by a predefined threshold of lateral board sway and 2) Proportional-mode E-stim as the stimulation frequency proportional to the amount of lateral board sway. All subjects were distracted from the balancing task by the n-back counting task, to test subjects' balancing capability with minimal cognitive involvement.

Results: Proportional-mode E-stim, along with the n-back counting task, increased the balance time from 1.86 ± 0.03 s to 1.98 ± 0.04 s (p = 0.010). However, discrete-mode E-stim did not change the balance time (p = 0.669). Proportional-mode E-stim also increased the time duration per each swayed state (p = 0.035) while discrete-mode E-stim did not (p = 0.053).

Discussion: These results suggest that proportional-mode E-stim is more effective than discrete-mode E-stim on improving standing balance. It is perhaps because the proportional electrotactile feedback better mimics the natural tactile sensation of foot pressure than its discrete counterpart.

Keywords: calcaneal nerve stimulation; electrical stimulation; electrotactile feedback; neuromodulation; standing balance.

Grants and funding

This work was supported by Craig H. Neilsen Foundation (No. 882102), National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 00209864), and Institute of Information & communications Technology Planning & Evaluation (IP) grant funded by the Korea government (MSIT) (No.2020-0-01373, Artificial Intelligence Graduate School Program (Hanyang University) and IITP-(2024)-RS-2023-00253914, AI Semiconductor Graduate School Program (Hanyang University)).