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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