Effects of anodal transcranial direct current stimulation on implicit motor learning and language‐related brain function: An fMRI study

Abstract

Aim Anodal transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) is known as a useful application for improving depressive symptoms or cognitive performance. Antidepressive effects by anodal tDCS over the left DLPFC are expected, but the neural mechanisms of these effects are still unclear. Further, in depression, reduced performance and left prefrontal hypofunction during the verbal fluency task (VFT) are generally known. However, few studies have examined the effect of tDCS on the language‐related cerebral network. We aimed to investigate whether anodal tDCS at the left DLPFC affects cognitive performance and the neural basis of verbal fluency. Methods Nineteen healthy volunteers participated in this study. The effects of tDCS on cognitive behavior and cerebral function were evaluated by (i) performance and accuracy of implicit/explicit motor learning task (serial reaction time task/sequential finger‐tapping task), and (ii) cerebral activation while the subjects were performing the VFT by using a functional MRI protocol of a randomized sham‐controlled, within‐subjects crossover design. Results Reaction times of the implicit motor learning task were significantly faster with tDCS in comparison with the sham. Further, language‐related left prefrontal‐parahippocampal‐parietal activation was significantly less with tDCS compared with the sham. Significant correlation was observed between shortened response time in serial reaction time task and decreased cerebral activation during VFT with tDCS. Conclusion Anodal tDCS over the left DLPFC could improve cognitive behavior of implicit motor learning by improving brain function of the frontoparietal‐parahippocampal region related to motor learning, as well as language‐related regions.

The Efficacy of Transcranial Direct Current Stimulation in Enhancing Surgical Skill Acquisition: A Preliminary Meta-Analysis of Randomized Controlled Trials

“…The enhancing effect of tDCS on the targeted cortex has been found to improve participants' perception, cognitive functioning, and motor function [14]. Stimulation site over the prefrontal cortex would result in improvement in both the executive function and motor-learning function in healthy volunteer through brain function modulation [12]. Similarly, the application of tDCS enhancement over participants' primary motor cortex was found to be associated with significant improvements in balance control in stroke patients and healthy subjects [18,23].…”

“…Transcranial direct-current stimulation (tDCS) may improve both the executive function and motor-learning function in healthy volunteer through brain function modulation [12], which two functions were the key components in surgical skill acquisition/training. The potential beneficial effect on executive function might be derived from its enhancing effect on long-term potentiation and brain-derived neurotrophic factor expression in the stimulated brain regions [13].…”

Functional whole-brain mechanisms underlying effects of tDCS on athletic performance of male rowing athletes revealed by resting-state fMRI

“…The neuromodulatory effect of tDCS depends on the polarity: excitatory effect under the anodal electrode and inhibitory effect under the cathodal electrode, which is related to the shift of the resting membrane potential of the targeted neural cells ( Stagg and Nitsche, 2011 ). With tDCS, a weak electric direct current is applied to the scalp with the intention to modulate the activity of a targeted brain area, which has been proven to induce positive effects on the physical performance of athletes ( Grandperrin et al, 2020 ; Nakashima et al, 2021 ). In this study, we also observed significant improvements in the athletic performance of male rowing athletes received tDCS over the left primary motor cortex while undergoing regular training.…”

Effects of transcranial direct current stimulation on motor skills learning in healthy adults through the activation of different brain regions: A systematic review

“…The electrode size in seven studies was 25 cm 2 (Marquez et al, 2013;Cantarero et al, 2015;Zhu et al, 2015;Apolinario-Souza et al, 2016;Wessel et al, 2016;Debarnot et al, 2019;Parma et al, 2021). The electrode size in three studies was 35 cm 2 (Tecchio et al, 2010;Kantak et al, 2012;Nakashima et al, 2021) and that in one study was 24 cm 2 (Soekadar et al, 2015). The current density of 11 studies ranged from 0.03 to 0.08 mA/ cm 2 .…”