title: Contributions of the cerebellum and the motor cortex to acquisition and retention of motor memories.
abstract: We investigated the contributions of the cerebellum and the motor cortex (M1) to acquisition and retention of human motor memories in a force field reaching task. We found that anodal transcranial direct current stimulation (tDCS) of the cerebellum, a technique that is thought to increase neuronal excitability, increased the ability to learn from error and form an internal model of the field, while cathodal cerebellar stimulation reduced this error-dependent learning. In addition, cathodal cerebellar stimulation disrupted the ability to respond to error within a reaching movement, reducing the gain of the sensory-motor feedback loop. By contrast, anodal M1 stimulation had no significant effects on these variables. During sham stimulation, early in training the acquired motor memory exhibited rapid decay in error-clamp trials. With further training the rate of decay decreased, suggesting that with training the motor memory was transformed from a labile to a more stable state. Surprisingly, neither cerebellar nor M1 stimulation altered these decay patterns. Participants returned 24hours later and were re-tested in error-clamp trials without stimulation. The cerebellar group that had learned the task with cathodal stimulation exhibited significantly impaired retention, and retention was not improved by M1 anodal stimulation. In summary, non-invasive cerebellar stimulation resulted in polarity-dependent up- or down-regulation of error-dependent motor learning. In addition, cathodal cerebellar stimulation during acquisition impaired the ability to retain the motor memory overnight. Thus, in the force field task we found a critical role for the cerebellum in both formation of motor memory and its retention.
authors.affiliation: Laboratory for Computational Motor Control, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Herzfeld
authors.affiliation: Laboratory for Computational Motor Control, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Lyon Research Center of Neuroscience, ImpAct team, INSERM U1028, CNRS UMR5292, Lyon 1 University, 69676 Bron, France; Plate-forme Mouvement et Handicap, Hospices Civils de Lyon, Centre de Recherche en Neurosciences de Lyon, 69230, Saint-Genis Laval, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Pastor
authors.affiliation: Laboratory for Computational Motor Control, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Adrian M
authors.initials: AM
authors.lastname: Haith
authors.affiliation: Lyon Research Center of Neuroscience, ImpAct team, INSERM U1028, CNRS UMR5292, Lyon 1 University, 69676 Bron, France; Plate-forme Mouvement et Handicap, Hospices Civils de Lyon, Centre de Recherche en Neurosciences de Lyon, 69230, Saint-Genis Laval, France.
authors.forename: Yves
authors.initials: Y
authors.lastname: Rossetti
authors.affiliation: Laboratory for Computational Motor Control, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Reza
authors.initials: R
authors.lastname: Shadmehr
authors.affiliation: Lyon Research Center of Neuroscience, ImpAct team, INSERM U1028, CNRS UMR5292, Lyon 1 University, 69676 Bron, France; Plate-forme Mouvement et Handicap, Hospices Civils de Lyon, Centre de Recherche en Neurosciences de Lyon, 69230, Saint-Genis Laval, France; FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, UK.
authors.forename: Jacinta
authors.initials: J
authors.lastname: O'Shea
mesh_terms: D000293:Adolescent; D000328:Adult; D002531:Cerebellum / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D012153:Retention, Psychology / Q000502:physiology; D065908:Transcranial Direct Current Stimulation; D055815:Young Adult
keywords: Adaptation; Consolidation; Force field; Generalization; Motor control; Reaching; Retention; tDCS