title: Practicing Novel, Praxis-Like Movements: Physiological Effects of Repetition.
abstract: Our primary goal was to develop and validate a task that could provide evidence about how humans learn praxis gestures, such as those involving the use of tools. To that end, we created a video-based task in which subjects view a model performing novel, meaningless one-handed actions with kinematics similar to praxis gestures. Subjects then imitated the movements with their right hand. Trials were repeated six times to examine practice effects. EEG was recorded during the task. As a control, subjects watched videos of a model performing a well-established (over learned) tool-use gesture. These gestures were also imitated six times. Demonstrating convergent validity, EEG measures of task-related cortical activation were similar in topography and frequency between the novel gesture task and the overlearned, praxis gesture task. As in studies assessing motor skill learning with simpler tasks, cortical activation during novel gesture learning decreased as the same gestures were repeated. In the control condition, repetition of overlearned tool-use gestures were also associated with reductions in activation, though to a lesser degree. Given that even overlearned, praxis gestures show constriction of EEG activity with repetition, it is possible that that attentional effects drive some of the repetition effects seen in EEG measures of activation during novel gesture repetition.
authors.affiliation: Clinical Neurophysiology Laboratory, Department of Neurology and Developmental Medicine, Kennedy Krieger InstituteBaltimore, MD, USA; Department of Neurology, Johns Hopkins University School of MedicineBaltimore, MD, USA; Department of Psychological and Brain Sciences, Johns Hopkins University Krieger School of Arts and SciencesBaltimore, MD, USA.
authors.forename: Joshua B
authors.initials: JB
authors.lastname: Ewen
authors.affiliation: Clinical Neurophysiology Laboratory, Department of Neurology and Developmental Medicine, Kennedy Krieger InstituteBaltimore, MD, USA; Department of Neurology, Johns Hopkins University School of MedicineBaltimore, MD, USA.
authors.forename: Ajay S
authors.initials: AS
authors.lastname: Pillai
authors.affiliation: Clinical Neurophysiology Laboratory, Department of Neurology and Developmental Medicine, Kennedy Krieger Institute Baltimore, MD, USA.
authors.forename: Danielle
authors.initials: D
authors.lastname: McAuliffe
authors.affiliation: Clinical Neurophysiology Laboratory, Department of Neurology and Developmental Medicine, Kennedy Krieger Institute Baltimore, MD, USA.
authors.forename: Balaji M
authors.initials: BM
authors.lastname: Lakshmanan
authors.affiliation: Center for Neurodevelopmental and Imaging Research, Kennedy Krieger Institute Baltimore, MD, USA.
authors.forename: Katarina
authors.initials: K
authors.lastname: Ament
authors.affiliation: Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health Bethesda, MD, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Hallett
authors.affiliation: Department of Neurology, Johns Hopkins University School of Medicine Baltimore, MD, USA.
authors.forename: Nathan E
authors.initials: NE
authors.lastname: Crone
authors.affiliation: Clinical Neurophysiology Laboratory, Department of Neurology and Developmental Medicine, Kennedy Krieger InstituteBaltimore, MD, USA; Department of Neurology, Johns Hopkins University School of MedicineBaltimore, MD, USA; Center for Neurodevelopmental and Imaging Research, Kennedy Krieger InstituteBaltimore, MD, USA; Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of MedicineBaltimore, MD, USA.
authors.forename: Stewart H
authors.initials: SH
authors.lastname: Mostofsky
keywords: EEG; attention; event-related desynchronization; gesture production; motor learning; praxis; repetition suppression