Open AccessEffects of anodal transcranial direct current stimulation on motor evoked potentials variability in humans
Author(s) -
Bashir Shahid,
Ahmad Shafiq,
Alatefi Moath,
Hamza Ali,
Sharaf Mohamed,
Fecteau Shirely,
Yoo Woo Kyoung
Publication year - 2019
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.14087
Subject(s) - transcranial direct current stimulation , motor cortex , stimulation , transcranial magnetic stimulation , primary motor cortex , brain stimulation , medicine , crossover study , physical medicine and rehabilitation , reproducibility , neuroscience , psychology , placebo , pathology , statistics , alternative medicine , mathematics
Motor evoked potentials ( MEP s) obtained from transcranial magnetic stimulation ( TMS ) allow corticospinal excitability ( CSE ) to be measured in the human primary motor cortex (M1). CSE responses to transcranial direct current stimulation ( tDCS ) protocols are highly variable. Here, we tested the reproducibility and reliability of individual MEP s following a common anodal tDCS protocol. In this study, 32 healthy subjects received anodal tDCS stimulation over the left M1 for three durations ( tDCS ‐T5, tDCS ‐T10, and tDCS ‐T20 min) on separate days in a crossover‐randomized order. After the resting motor threshold ( RMT ) was determined for the contralateral first dorsal interosseous muscle, 15 single pulses 4–8 sec apart at an intensity of 120% RMT were delivered to the left M1 to determine the baseline MEP amplitude at T 0 , T 5 , T 10 , T 20 , T 30 , T 40 , T 50 , and T 60 min after stimulation for each durations. During TMS delivery, 3D images of the participant's cortex and hot spot were visualized for obtaining MEP s from same position. Our findings revealed that there was a significant MEP s improvement at T 0 ( P = 0.01) after 10 min of anodal stimulation. After the 20‐min stimulation duration, MEP s differed specifically at T 0, T 5, T 30 min ( P < 0.05). This indicates that tDCS is a promising tool to improve MEP s. Our observed variability in response to the tDCS protocol is consistent with other noninvasive brain stimulation studies.