Research articleThe effect of transcranial random noise stimulation on corticospinal excitability and motor performance
Introduction
Transcranial electric stimulation (tES) is a noninvasive brain stimulation (NIBS) technique that can alter the excitability of the cerebral cortex [16] and is applied as a rehabilitation tool for patients with stroke. Numerous studies have been conducted using transcranial direct current stimulation (tDCS), a typical tES method. Anodal tDCS for 10 min was reported to increase the primary motor cortex (M1) excitability [9] and to improve the motor performance [2,8]. However, a recent study suggests that the effect of tDCS varies and a stable effect is difficult to obtain [15]. A new tES method, transcranial random noise stimulation (tRNS), is highly effective for increasing cortical excitability. tRNS employs an alternating current stimulation ranging between 0.1 Hz and 640 Hz or 100 and 640 Hz. Terney et al. (2008) reported that the corticospinal excitability increase are lasting 60 min after tRNS stimulation over the M1 region at 1.0 mA for 10 min [13]. Inukai et al. (2016) demonstrated that tRNS increases the corticospinal excitability in a more stable way than anodal tDCS [6]. In addition, Prichard et al. (2014) reported that motor performance was improved after applying tRNS during motor tasks [10]. tRNS might improve motor performance as tRNS increases cortical excitability like tDCS but this remains to be clarified. The aim of the present study is to evaluate the influence of tRNS independent intervention on the M1 region with respect to corticospinal excitability and motor performance.
Section snippets
Subjects
The study included 16 right-handed adults (12 males, 4 females; average ± standard deviation = 21.0 ± 0.35 years old) without neurological disease. All subject, after being fully informed on the study goals and assessments, provided a written consent to participate in this study. This study was conducted in accordance with the principles of the Declaration of Helsinki and was approved by the ethics committee of Niigata University of Health and Welfare.
Transcranial random noise stimulation (tRNS)
tRNS was delivered using a DC-STIMULATOR
MEP amplitude
Two-way repeated-measures ANOVA revealed a significant stimulus condition × time interaction (F(3, 29) = 8.41, p < 0.01 partial η2 = 0.359) and the main effect of the stimulus condition factor (F(1, 15) = 15.04, p < 0.01, partial η2 = 0.403). No significant difference was found the main effect of time factor (F(2, 30) = 3.27, p = 0.73, partial η2 = 0.247). In the tRNS condition, post hoc analyses showed that the MEP amplitudes at post-0 min (p < 0.05) and post-10 min (p < 0.05) were
Discussion
This study investigated whether tRNS over the M1 region does affect corticospinal excitability and motor performance. We demonstrated that the corticospinal excitability is increased starting immediately after tRNS intervention, and the motor performance is improved at 10 min after tRNS intervention. Therefore, tRNS over the M1 region shows efficacy in increasing corticospinal excitability and improving motor performance.
tRNS at 1.0 mA for 10 min increased the MEP amplitude immediately after
Conclusions
This study demonstrated that the tRNS over the M1 region in healthy subject increases the corticospinal excitability and contributes to the improvement of motor performance.
Funding sources
This work was supported by a Grant-in-Aid for Young Scientists (B) 17K13073 from the Japan Society for the Promotion of Science.
Conflicts of interest
All authors report no conflict of interest.
Acknowledgement
The authors would like to thank Enago (www.enago.jp) for the English language review.
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2021, Behavioural Brain ResearchCitation Excerpt :However, regarding the dissociation between changes in motor function and MEP amplitude observed in this study, previous studies have reported that the wider the frequency bands used for tRNS, the greater the increase in corticospinal excitability [42]. Furthermore, several previous studies investigating the effects of tRNS on corticospinal excitability reported that all-frequency band tRNS increase corticospinal excitability more than that in the sham condition [17,19,20]. These reports suggest that all-frequency band tRNS may be most effective in increasing corticospinal excitability and that the optimal frequency bands for tRNS vary for improving corticospinal excitability and motor function.