title: Monitoring transcranial direct current stimulation induced changes in cortical excitability during the serial reaction time task.
abstract: The measurement of the motor evoked potential (MEP) amplitudes using single pulse transcranial magnetic stimulation (TMS) is a common method to observe changes in motor cortical excitability. The level of cortical excitability has been shown to change during motor learning. Conversely, motor learning can be improved by using anodal transcranial direct current stimulation (tDCS). In the present study, we aimed to monitor cortical excitability changes during an implicit motor learning paradigm, a version of the serial reaction time task (SRTT). Responses from the first dorsal interosseous (FDI) and forearm flexor (FLEX) muscles were recorded before, during and after the performance of the SRTT. Online measurements were combined with anodal, cathodal or sham tDCS for the duration of the SRTT. Negative correlations between the amplitude of online FDI MEPs and SRTT reaction times (RTs) were observed across the learning blocks in the cathodal condition (higher average MEP amplitudes associated with lower RTs) but no significant differences in the anodal and sham conditions. tDCS did not have an impact on SRTT performance, as would be predicted based on previous studies. The offline before-after SRTT MEP amplitudes showed an increase after anodal and a tendency to decrease after cathodal stimulation, but these changes were not significant. The combination of different interventions during tDCS might result in reduced efficacy of the stimulation that in future studies need further attention.
authors.affiliation: Department of Clinical Neurophysiology, University Medical Center, Georg-August University, Göttingen, Germany; Institute of Medical Psychology and Medical Sociology, University Medical Center,Georg-August University, Göttingen, Germany; Institute of Psychology, Friedrich Schiller University of Jena, Jena, Germany. Electronic address: g.ambrus@gmail.com.
authors.forename: Géza Gergely
authors.initials: GG
authors.lastname: Ambrus
authors.affiliation: Department of Clinical Neurophysiology, University Medical Center, Georg-August University, Göttingen, Germany; Department of Epileptology, University of Bonn, Bonn, Germany.
authors.forename: Leila
authors.initials: L
authors.lastname: Chaieb
authors.affiliation: Department of Clinical Neurophysiology, University Medical Center, Georg-August University, Göttingen, Germany; Laboratory for Neurogastroentorology, Alimentary Pharmabiotic Centre (APC), University College Cork, Cork, Ireland.
authors.forename: Roman
authors.initials: R
authors.lastname: Stilling
authors.affiliation: Department of Clinical Neurophysiology, University Medical Center, Georg-August University, Göttingen, Germany; Department of Psychiatry, Imland Clinic Rendsburg, 24768, Rendsburg, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Rothkegel
authors.affiliation: Department of Clinical Neurophysiology, University Medical Center, Georg-August University, Göttingen, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Antal
authors.affiliation: Department of Clinical Neurophysiology, University Medical Center, Georg-August University, Göttingen, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Paulus
mesh_terms: D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology*; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D007858:Learning; D008297:Male; D009044:Motor Cortex / Q000502:physiology; D009048:Motor Skills; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D010775:Photic Stimulation; D011597:Psychomotor Performance; D011930:Reaction Time; D065908:Transcranial Direct Current Stimulation; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: Motor cortex (M1); Serial reaction time task (SRTT); Transcranial direct current stimulation (tDCS); Transcranial magnetic stimulation (TMS)