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

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 eval-uation of tDCS montage is not reported for the lower limbs. In this study, we computationally investi-gated 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. ?? 2023 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Automated summary

This study computationally investigated the effects of tDCS montage on the lower limbs by evaluating the electric field intensity, polarity, and co-stimulation of cortical areas using high-resolution head models. The results showed that the C1-C2 montage delivered higher electric field intensities and reached deeper regions of the lower-limb motor area. It also resulted in uniform polarization on the same hemisphere target with comparable intensities between hemispheres but with higher variability. In conclusion, proper montage selection is important for targeting deeper regions and achieving uniform polarization in the lower-limb motor area. Significance: 8/10.