title: Enhancing Hebbian Learning to Control Brain Oscillatory Activity.
abstract: Sensorimotor rhythms (SMR, 8-15 Hz) are brain oscillations associated with successful motor performance, imagery, and imitation. Voluntary modulation of SMR can be used to control brain-machine interfaces (BMI) in the absence of any physical movements. The mechanisms underlying acquisition of such skill are unknown. Here, we provide evidence for a causal link between function of the primary motor cortex (M1), active during motor skill learning and retention, and successful acquisition of abstract skills such as control over SMR. Thirty healthy participants were trained on 5 consecutive days to control SMR oscillations. Each participant was randomly assigned to one of 3 groups that received either 20 min of anodal, cathodal, or sham transcranial direct current stimulation (tDCS) over M1. Learning SMR control across training days was superior in the anodal tDCS group relative to the other 2. Cathodal tDCS blocked the beneficial effects of training, as evidenced with sham tDCS. One month later, the newly acquired skill remained superior in the anodal tDCS group. Thus, application of weak electric currents of opposite polarities over M1 differentially modulates learning SMR control, pointing to this primary cortical region as a common substrate for acquisition of physical motor skills and learning to control brain oscillatory activity.
authors.affiliation: Human Cortical Physiology and Stroke Neurorehabilitation Section, National Institute of Neurological Disorders and Stroke, NIH, USA Applied Neurotechnology Lab, Department of Psychiatry and Psychotherapy, University Hospital of Tübingen, Tübingen, Germany Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany.
authors.forename: Surjo R
authors.initials: SR
authors.lastname: Soekadar
authors.affiliation: Human Cortical Physiology and Stroke Neurorehabilitation Section, National Institute of Neurological Disorders and Stroke, NIH, USA Applied Neurotechnology Lab, Department of Psychiatry and Psychotherapy, University Hospital of Tübingen, Tübingen, Germany Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Witkowski
authors.affiliation: Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany Ospedale San Camillo, IRCCS, Venezia, Italy.
authors.forename: Niels
authors.initials: N
authors.lastname: Birbaumer
authors.affiliation: Human Cortical Physiology and Stroke Neurorehabilitation Section, National Institute of Neurological Disorders and Stroke, NIH, USA.
authors.forename: Leonardo G
authors.initials: LG
authors.lastname: Cohen
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007858:Learning / Q000502:physiology*; D015225:Magnetoencephalography; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009048:Motor Skills / Q000502:physiology*; D009068:Movement / Q000502:physiology; D010507:Periodicity; D011897:Random Allocation; D012153:Retention, Psychology; D013997:Time Factors; D065908:Transcranial Direct Current Stimulation; D055815:Young Adult
keywords: Hebbian learning; brain stimulation; motor cortex; sensorimotor rhythms