TY - JOUR
T1 - The effects of bi-hemispheric M1-M1 transcranial direct current stimulation on primary motor cortex neurophysiology and metabolite concentration
AU - Tremblay, Sara
AU - Lafleur, Louis Philippe
AU - Proulx, Sébastien
AU - Beaulé, Vincent
AU - Latulipe-Loiselle, Alex
AU - Doyon, Julien
AU - Marjaska, Magorzata
AU - Théoret, Hugo
N1 - Publisher Copyright:
© 2016 - IOS Press and the authors.
PY - 2016/8/13
Y1 - 2016/8/13
N2 - Purpose: The aim of the present study was to assess, in healthy individuals, the impact of M1-M1 tDCS on primary motor cortex excitability using transcranial magnetic stimulation and sensorimotor metabolite concentration using 1H-MRS. Methods: For both experiments, each participant received the three following interventions (20 min tDCS, 1 mA): left-anodal/right-cathodal, left-cathodal/right-anodal, sham. The effects of tDCS were assessed via motor evoked potentials (experiment 1) and metabolite concentrations (experiment 2) immediately after and 12 minutes following the end of stimulation and compared to baseline measurement. Results: No effect of M1-M1 tDCS on corticospinal excitability was found. Similarly, M1-M1 tDCS did not significantly modulate metabolite concentrations. High inter-subject variability was noted. Response rate analysis showed a tendency towards inhibition following left-anodal/right-cathodal tDCS in 50 of participants and increased GABA levels in 45 of participants. Conclusion: In line with recent studies showing important inter-subject variability following M1-supraorbital tDCS, the present data show that M1-M1 stimulation is also associated with large response variability. The absence of significant effects suggests that current measures may lack sensitivity to assess changes in M1 neurophysiology and metabolism associated with M1-M1 tDCS.
AB - Purpose: The aim of the present study was to assess, in healthy individuals, the impact of M1-M1 tDCS on primary motor cortex excitability using transcranial magnetic stimulation and sensorimotor metabolite concentration using 1H-MRS. Methods: For both experiments, each participant received the three following interventions (20 min tDCS, 1 mA): left-anodal/right-cathodal, left-cathodal/right-anodal, sham. The effects of tDCS were assessed via motor evoked potentials (experiment 1) and metabolite concentrations (experiment 2) immediately after and 12 minutes following the end of stimulation and compared to baseline measurement. Results: No effect of M1-M1 tDCS on corticospinal excitability was found. Similarly, M1-M1 tDCS did not significantly modulate metabolite concentrations. High inter-subject variability was noted. Response rate analysis showed a tendency towards inhibition following left-anodal/right-cathodal tDCS in 50 of participants and increased GABA levels in 45 of participants. Conclusion: In line with recent studies showing important inter-subject variability following M1-supraorbital tDCS, the present data show that M1-M1 stimulation is also associated with large response variability. The absence of significant effects suggests that current measures may lack sensitivity to assess changes in M1 neurophysiology and metabolism associated with M1-M1 tDCS.
KW - GABA
KW - Magnetic resonance spectroscopy
KW - glutamate
KW - motor cortex
KW - transcranial direct current stimulation
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U2 - 10.3233/RNN-150569
DO - 10.3233/RNN-150569
M3 - Article
C2 - 27232951
AN - SCOPUS:84983354586
SN - 0922-6028
VL - 34
SP - 587
EP - 602
JO - Restorative Neurology and Neuroscience
JF - Restorative Neurology and Neuroscience
IS - 4
ER -