Can electric fields explain inter-individual variability in transcranial direct current stimulation of the motor cortex?

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Can electric fields explain inter-individual variability in transcranial direct current stimulation of the motor cortex? / Laakso, Ilkka; Mikkonen, Marko; Koyama, Soichiro; Hirata, Akimasa; Tanaka, Satoshi.

In: Scientific Reports, Vol. 9, No. 1, 626, 24.01.2019.

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@article{10a86bdd3b854c66ac792f759b79bec4,
title = "Can electric fields explain inter-individual variability in transcranial direct current stimulation of the motor cortex?",
abstract = "The effects of transcranial direct current stimulation (tDCS) on motor cortical excitability are highly variable between individuals. Inter-individual differences in the electric fields generated in the brain by tDCS might play a role in the variability. Here, we explored whether these fields are related to excitability changes following anodal tDCS of the primary motor cortex (M1). Motor evoked potentials (MEPs) were measured in 28 healthy subjects before and after 20 min sham or 1 mA anodal tDCS of right M1 in a double-blind crossover design. The electric fields were individually modelled based on magnetic resonance images. Statistical analysis indicated that the variability in the MEPs could be partly explained by the electric fields, subjects with the weakest and strongest fields tending to produce opposite changes in excitability. To explain the findings, we hypothesized that the likely locus of action was in the hand area of M1, and the effective electric field component was that in the direction normal to the cortical surface. Our results demonstrate that a large part of inter-individual variability in tDCS may be due to differences in the electric fields. If this is the case, electric field dosimetry could be useful for controlling the neuroplastic effects of tDCS.",
keywords = "NONINVASIVE BRAIN-STIMULATION, LEAST-SQUARES REGRESSION, HUMAN CEREBRAL-CORTEX, CORTICAL EXCITABILITY, TDCS, PLASTICITY, MODULATION, INTENSITY, SYSTEM, IMPACT",
author = "Ilkka Laakso and Marko Mikkonen and Soichiro Koyama and Akimasa Hirata and Satoshi Tanaka",
year = "2019",
month = "1",
day = "24",
doi = "10.1038/s41598-018-37226-x",
language = "English",
volume = "9",
journal = "Scientific Reports",
issn = "2045-2322",
number = "1",

}

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TY - JOUR

T1 - Can electric fields explain inter-individual variability in transcranial direct current stimulation of the motor cortex?

AU - Laakso, Ilkka

AU - Mikkonen, Marko

AU - Koyama, Soichiro

AU - Hirata, Akimasa

AU - Tanaka, Satoshi

PY - 2019/1/24

Y1 - 2019/1/24

N2 - The effects of transcranial direct current stimulation (tDCS) on motor cortical excitability are highly variable between individuals. Inter-individual differences in the electric fields generated in the brain by tDCS might play a role in the variability. Here, we explored whether these fields are related to excitability changes following anodal tDCS of the primary motor cortex (M1). Motor evoked potentials (MEPs) were measured in 28 healthy subjects before and after 20 min sham or 1 mA anodal tDCS of right M1 in a double-blind crossover design. The electric fields were individually modelled based on magnetic resonance images. Statistical analysis indicated that the variability in the MEPs could be partly explained by the electric fields, subjects with the weakest and strongest fields tending to produce opposite changes in excitability. To explain the findings, we hypothesized that the likely locus of action was in the hand area of M1, and the effective electric field component was that in the direction normal to the cortical surface. Our results demonstrate that a large part of inter-individual variability in tDCS may be due to differences in the electric fields. If this is the case, electric field dosimetry could be useful for controlling the neuroplastic effects of tDCS.

AB - The effects of transcranial direct current stimulation (tDCS) on motor cortical excitability are highly variable between individuals. Inter-individual differences in the electric fields generated in the brain by tDCS might play a role in the variability. Here, we explored whether these fields are related to excitability changes following anodal tDCS of the primary motor cortex (M1). Motor evoked potentials (MEPs) were measured in 28 healthy subjects before and after 20 min sham or 1 mA anodal tDCS of right M1 in a double-blind crossover design. The electric fields were individually modelled based on magnetic resonance images. Statistical analysis indicated that the variability in the MEPs could be partly explained by the electric fields, subjects with the weakest and strongest fields tending to produce opposite changes in excitability. To explain the findings, we hypothesized that the likely locus of action was in the hand area of M1, and the effective electric field component was that in the direction normal to the cortical surface. Our results demonstrate that a large part of inter-individual variability in tDCS may be due to differences in the electric fields. If this is the case, electric field dosimetry could be useful for controlling the neuroplastic effects of tDCS.

KW - NONINVASIVE BRAIN-STIMULATION

KW - LEAST-SQUARES REGRESSION

KW - HUMAN CEREBRAL-CORTEX

KW - CORTICAL EXCITABILITY

KW - TDCS

KW - PLASTICITY

KW - MODULATION

KW - INTENSITY

KW - SYSTEM

KW - IMPACT

UR - http://www.scopus.com/inward/record.url?scp=85060546118&partnerID=8YFLogxK

U2 - 10.1038/s41598-018-37226-x

DO - 10.1038/s41598-018-37226-x

M3 - Article

VL - 9

JO - Scientific Reports

JF - Scientific Reports

SN - 2045-2322

IS - 1

M1 - 626

ER -

ID: 31970959