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Title: Focality-oriented selection of current dose for transcranial direct current stimulation
Authors: Kashyap, Rajan
Bhattacharjee, Sagarika
Arumugam, Ramaswamy
Bharath, Rose Dawn
Udupa, Kaviraja
Oishi, Kenichi
Desmond, John E.
Chen, Annabel Shen-Hsing
Guan, Cuntai
Keywords: Science::Medicine
Issue Date: 2021
Source: Kashyap, R., Bhattacharjee, S., Arumugam, R., Bharath, R. D., Udupa, K., Oishi, K., Desmond, J. E., Chen, A. S. & Guan, C. (2021). Focality-oriented selection of current dose for transcranial direct current stimulation. Journal of Personalized Medicine, 11(9), 940-.
Project: RIE2020
Journal: Journal of Personalized Medicine
Abstract: Background: In transcranial direct current stimulation (tDCS), the injected current becomes distributed across the brain areas. The objective is to stimulate the target region of interest (ROI) while minimizing the current in non-target ROIs (the 'focality' of tDCS). For this purpose, determining the appropriate current dose for an individual is difficult. Aim: To introduce a dose-target determination index (DTDI) to quantify the focality of tDCS and examine the dose-focality relationship in three different populations. Method: Here, we extended our previous toolbox i-SATA to the MNI reference space. After a tDCS montage is simulated for a current dose, the i-SATA(MNI) computes the average (over voxels) current density for every region in the brain. DTDI is the ratio of the average current density at the target ROI to the ROI with a maximum value (the peak region). Ideally, target ROI should be the peak region, so DTDI shall range from 0 to 1. The higher the value, the better the dose. We estimated the variation of DTDI within and across individuals using T1-weighted brain images of 45 males and females distributed equally across three age groups: (a) young adults (20 ≤ x ˂ 40 years), (b) mid adults (40 ≤ x ˂ 60 years), and (c) older adults (60 ≤ x ˂ 80 years). DTDI's were evaluated for the frontal montage with electrodes at F3 and the right supraorbital for three current doses of 1 mA, 2 mA, and 3 mA, with the target ROI at the left middle frontal gyrus. Result: As the dose is incremented, DTDI may show (a) increase, (b) decrease, and (c) no change across the individuals depending on the relationship (nonlinear or linear) between the injected tDCS current and the distribution of current density in the target ROI. The nonlinearity is predominant in older adults with a decrease in focality. The decline is stronger in males. Higher current dose at older age can enhance the focality of stimulation. Conclusion: DTDI provides information on which tDCS current dose will optimize the focality of stimulation. The recommended DTDI dose should be prioritized based on the age (>40 years) and sex (especially for males) of an individual. The toolbox i-SATA(MNI) is freely available.
ISSN: 2075-4426
DOI: 10.3390/jpm11090940
Rights: © 2021 The Author(s). Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (
Fulltext Permission: open
Fulltext Availability: With Fulltext
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SCSE Journal Articles
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