Anke Ninija Karabanov1,2, Keiichiro Shindo1,3, Yuko Shindo1,3, Estelle Raffin1,4, Hartwig Roman Siebner1,5,6. 1. Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark. 2. Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark. 3. Department of Rehabilitation Medicine, Keio University School of Medicine, Shinjyuku-ku, Japan. 4. Center for Neuroprosthetics and Brain Mind Institute, Swiss Federal Institute of Technology, Geneva, Switzerland. 5. Institute for Clinical Medicine, University of Copenhagen, Copenhagen, Denmark. 6. Department of Neurology, Copenhagen University Hospital Bispebjerg, Copenhagen, Denmark.
Abstract
BACKGROUND: Transcranial direct current stimulation (TDCS) targeting the primary motor hand area (M1-HAND) may induce lasting shifts in corticospinal excitability, but after-effects show substantial inter-individual variability. Functional magnetic resonance imaging (fMRI) can probe after-effects of TDCS on regional neural activity on a whole-brain level. OBJECTIVE: Using a double-blinded cross-over design, we investigated whether the individual change in corticospinal excitability after TDCS of M1-HAND is associated with changes in task-related regional activity in cortical motor areas. METHODS: Seventeen healthy volunteers (10 women) received 20 min of real (0.75 mA) or sham TDCS on separate days in randomized order. Real and sham TDCS used the classic bipolar set-up with the anode placed over right M1-HAND. Before and after each TDCS session, we recorded motor evoked potentials (MEP) from the relaxed left first dorsal interosseus muscle after single-pulse transcranial magnetic stimulation(TMS) of left M1-HAND and performed whole-brain fMRI at 3 Tesla while participants completed a visuomotor tracking task with their left hand. We also assessed the difference in MEP latency when applying anterior-posterior and latero-medial TMS pulses to the precentral hand knob (AP-LM MEP latency). RESULTS: Real TDCS had no consistent aftereffects on mean MEP amplitude, task-related activity or motor performance. Individual changes in MEP amplitude, measured directly after real TDCS showed a positive linear relationship with individual changes in task-related activity in the supplementary motor area and AP-LM MEP latency. CONCLUSION: Functional aftereffects of classical bipolar anodal TDCS of M1-HAND on the motor system vary substantially across individuals. Physiological features upstream from the primary motor cortex may determine how anodal TDCS changes corticospinal excitability.
BACKGROUND: Transcranial direct current stimulation (TDCS) targeting the primary motor hand area (M1-HAND) may induce lasting shifts in corticospinal excitability, but after-effects show substantial inter-individual variability. Functional magnetic resonance imaging (fMRI) can probe after-effects of TDCS on regional neural activity on a whole-brain level. OBJECTIVE: Using a double-blinded cross-over design, we investigated whether the individual change in corticospinal excitability after TDCS of M1-HAND is associated with changes in task-related regional activity in cortical motor areas. METHODS: Seventeen healthy volunteers (10 women) received 20 min of real (0.75 mA) or sham TDCS on separate days in randomized order. Real and sham TDCS used the classic bipolar set-up with the anode placed over right M1-HAND. Before and after each TDCS session, we recorded motor evoked potentials (MEP) from the relaxed left first dorsal interosseus muscle after single-pulse transcranial magnetic stimulation(TMS) of left M1-HAND and performed whole-brain fMRI at 3 Tesla while participants completed a visuomotor tracking task with their left hand. We also assessed the difference in MEP latency when applying anterior-posterior and latero-medial TMS pulses to the precentral hand knob (AP-LM MEP latency). RESULTS: Real TDCS had no consistent aftereffects on mean MEP amplitude, task-related activity or motor performance. Individual changes in MEP amplitude, measured directly after real TDCS showed a positive linear relationship with individual changes in task-related activity in the supplementary motor area and AP-LM MEP latency. CONCLUSION: Functional aftereffects of classical bipolar anodal TDCS of M1-HAND on the motor system vary substantially across individuals. Physiological features upstream from the primary motor cortex may determine how anodal TDCS changes corticospinal excitability.
Keywords:
functional magnetic resonance imaging (fMRI); inter-individual variability; motor evoked potentials; non-invasive brain stimulation; primary motor cortex (M1); supplementary motor area (SMA); transcrancial magnetic stimulation (TMS); transcranial direct current stimulation (tDCS)
Authors: Sung Ho Jang; Sang Ho Ahn; Woo Mok Byun; Chung Sun Kim; Mi Young Lee; Yong Hyun Kwon Journal: Neurosci Lett Date: 2009-05-18 Impact factor: 3.046
Authors: Jessica Grundey; Nivethida Thirugnanasambandam; Kim Kaminsky; Anne Drees; Angela C Skwirba; Nicolas Lang; Walter Paulus; Michael A Nitsche Journal: J Neurosci Date: 2012-03-21 Impact factor: 6.167