Participants
In this study, the sample size of 77 was determined using G Power software, aiming for a 95% confidence level and 85% power, according to a similar study (Ciechanski & Kirton, 2017). The participants were included in the study if they were: 1) healthy, 2) right-handed and 3) aged between 18 and 35 years. The participants who: 1) reporting any history of neurological diseases such as Parkinson’s, Alzheimer’s, schizophrenia and dyslexia, 2) having psychological diseases, 3) receiving any brain stimulation affecting the central nervous system during the last two weeks, 4) having severe perceptual or memory problems (scores of less than 21, assessed by Mini-Mental Status Examination (MMSE)), 5) reporting the use of any sedative drugs in the last two days, 6) the presence of any symptoms of movement disorders in the upper limb of the right hand, 7) the presence of any symptoms of radiculopathy, carpal tunnel syndrome in the right hand as diagnosed by the researcher, 8) having visual and hearing dysfunction, 9) reporting dizziness, 10) alcoholism and 11) having heart rate regulator users were excluded from the study. In this study, 100 right-handed young and healthy volunteers were invited to assess for eligibility based on inclusion and exclusion criteria. Based on the inclusion and exclusion criteria of the study, 20 volunteers were excluded from the study and 80 healthy individuals included in the study. The remaining participants were randomly assigned to one of the five groups by computerized random number generator: 1) M1 c-tDCS with an intensity of 1 \RL mA, 2) M1 a-tDCS with an intensity of 1 \RL mA, 3) M1 c-tDCS with an intensity of 2 \RL mA, 4) M1 a-tDCS with an intensity of 2 mA and 5) M1 sham tDCS. Finally, 77 participants completed the entire study, and the data gathered from these individuals underwent analysis.
This study was approved by the Human Ethics Committee of the XXX (IR.SEMUMS.REC.1401.284) and registered as a clinical trial on the XXX (The registration number is IRCT2022102305677N2). The current study was performed during the first half of 2023 in the Neuromuscular Rehabilitation Research Center. A written informed consent was signed by all participants before participation in the study. This study met the CONSORT checklist criteria.
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