Computation of group-level electric field in lower limb motor area for different tDCS montages

Hiroki Hamajima; Jose Gomez-Tames; Shintaro Uehara; Yohei Otaka; Satoshi Tanaka; Akimasa Hirata

doi:10.1016/j.clinph.2023.03.009

Computation of group-level electric field in lower limb motor area for different tDCS montages

Clin Neurophysiol. 2023 Jun:150:69-78. doi: 10.1016/j.clinph.2023.03.009. Epub 2023 Mar 27.

Authors

Hiroki Hamajima¹, Jose Gomez-Tames², Shintaro Uehara³, Yohei Otaka⁴, Satoshi Tanaka⁵, Akimasa Hirata⁶

Affiliations

¹ Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Aichi 466-8555, Japan.
² Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Aichi 466-8555, Japan; Department of Medical Engineering, Graduate School of Engineering, Chiba University, Chiba 263-8522, Japan; Center for Frontier Medical Engineering, Chiba University, Chiba 263-8522, Japan. Electronic address: jgomez@chiba-u.jp.
³ Faculty of Rehabilitation, Fujita Health University School of Health Sciences, 470-1192, Japan.
⁴ Department of Rehabilitation Medicine I, Fujita Health University School of Medicine, 470-1192, Japan.
⁵ Department of Psychology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan.
⁶ Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Aichi 466-8555, Japan; Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi 466-8555, Japan.

PMID: 37023635
DOI: 10.1016/j.clinph.2023.03.009

Abstract

Objective: Transcranial direct current stimulation (tDCS) injects a weak electric current into the brain via electrodes attached to the scalp to modulate cortical excitability. tDCS is used to rebalance brain activity between affected and unaffected hemispheres in rehabilitation. However, a systematic quantitative evaluation of tDCS montage is not reported for the lower limbs. In this study, we computationally investigated the generated electric field intensity, polarity, and co-stimulation of cortical areas for lower limb targeting using high-resolution head models.

Methods: Volume conductor models have thus been employed to estimate the electric field in the brain. A total of 18 head models of healthy subjects were used to calculate the group-level electric fields generated from four montages of tDCS for modulation of lower limbs.

Results: C1-C2 montage delivered higher electric field intensities while reaching deeper regions of the lower-limb motor area. It produced a uniform polarization on the same hemisphere target with comparable intensities between hemispheres but with higher variability.

Conclusions: Proper montage selection allows reaching deeper regions of the lower-limb motor area with uniform polarization.

Significance: First systematic computational study providing support to tDCS experimental studies using montages for the lower limb while considering polarity factor for balancing brain activity.

Keywords: Computational model; Electric field; Group-level analysis; Leg; Lower-limb; Motor area; Transcranial direct current stimulation.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Brain / physiology
Cortical Excitability*
Humans
Motor Cortex*
Scalp
Transcranial Direct Current Stimulation*