title: Enhancing encoding of a motor memory in the primary motor cortex by cortical stimulation.
abstract: Motor training results in encoding of motor memories, a form of use-dependent plasticity. Here we tested the hypothesis that transcranial magnetic stimulation (TMS) synchronously applied to a motor cortex engaged in a motor training task could enhance this plastic process. Healthy volunteers were studied in four sessions: training consisting of performance of directionally specific voluntary thumb movements (Train alone), training with TMS delivered during the execution of the training movement in a strictly temporal relationship to the motor cortex contralateral (Train+TMS synchronous(contra)) and ipsilateral (Train+TMS synchronous(ipsi)) to the training hand, and training with TMS delivered asynchronous to the training movement to the motor cortex contralateral to the training hand (Train+TMS asynchronous(contra)). Train alone, Train+TMS synchronous(contra), and Train+TMS asynchronous(contra) but not Train+TMS synchronous(ipsi) elicited a clear motor memory. The longevity of the encoded memory was significantly enhanced by Train+TMS synchronous(contra) when compared with Train alone and Train+TMS asynchronous(contra). Therefore use-dependent encoding of a motor memory can be enhanced by synchronous Hebbian stimulation of the motor cortex that drives the training task and reduced by stimulation of the homologous ipsilateral motor cortex, a result relevant for studies of cognitive and physical rehabilitation.
authors.affiliation: Human Cortical Physiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-1428, USA. cathrin.buetefisch@uni-duesseldorf.de
authors.forename: Cathrin M
authors.initials: CM
authors.lastname: Bütefisch
authors.forename: Vikram
authors.initials: V
authors.lastname: Khurana
authors.forename: Leonid
authors.initials: L
authors.lastname: Kopylev
authors.forename: Leonardo G
authors.initials: LG
authors.lastname: Cohen
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D002540:Cerebral Cortex / Q000502:physiology*; D004574:Electromagnetic Fields; D004576:Electromyography; D004594:Electrophysiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007858:Learning / Q000502:physiology*; D008297:Male; D008568:Memory / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D009048:Motor Skills / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D013933:Thumb / Q000294:innervation / Q000502:physiology