title: Modulation of Cortical Inhibitory Circuits after Cathodal Transcranial Direct Current Stimulation over the Primary Motor Cortex.
abstract: Here, we aimed to evaluate whether cathodal transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) and primary somatosensory cortex (S1) can modulate cortical inhibitory circuits. Sixteen healthy subjects participated in this study. Cathodal tDCS was positioned over the left M1 (M1 cathodal) or left S1 (S1 cathodal) with an intensity of 1 mA for 10 min. Sham tDCS was applied for 10 min over the left M1 (sham). Motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) were recorded from the right abductor pollicis brevis (APB) muscle before the intervention (pre) and 10 and 30 min after the intervention (post 1 and post 2, respectively). Cortical inhibitory circuits were evaluated using short-interval intracortical inhibition (SICI) and short-latency afferent inhibition (SAI). M1 cathodal decreased single-pulse MEP amplitudes at post 1 and decreased SAI at post 1 and post 2; however, SICI did not exhibit any change. S1 cathodal and sham did not show any changes in MEP amplitudes at any of the three time points. These results demonstrated that cathodal tDCS over the M1 not only decreases the M1 excitability but also affects the cortical inhibitory circuits related to SAI.
authors: Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare Niigata, Japan.
authors: Ryoki
authors: R
authors: Sasaki
authors: Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare Niigata, Japan.
authors: Shota
authors: S
authors: Miyaguchi
authors: Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare Niigata, Japan.
authors: Shinichi
authors: S
authors: Kotan
authors: Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare Niigata, Japan.
authors: Sho
authors: S
authors: Kojima
authors: Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare Niigata, Japan.
authors: Hikari
authors: H
authors: Kirimoto
authors: Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare Niigata, Japan.
authors: Hideaki
authors: H
authors: Onishi
keywords: motor evoked potential; primary motor cortex; primary somatosensory cortex; short-interval intracortical inhibition; short-latency afferent inhibition; transcranial direct current stimulation