title: One hertz repetitive transcranial magnetic stimulation over dorsal premotor cortex enhances offline motor memory consolidation for sequence-specific implicit learning.
abstract: Consolidation of motor memories associated with skilled practice can occur both online, concurrent with practice, and offline, after practice has ended. The current study investigated the role of dorsal premotor cortex (PMd) in early offline motor memory consolidation of implicit sequence-specific learning. Thirty-three participants were assigned to one of three groups of repetitive transcranial magnetic stimulation (rTMS) over left PMd (5 Hz, 1 Hz or control) immediately following practice of a novel continuous tracking task. There was no additional practice following rTMS. This procedure was repeated for 4 days. The continuous tracking task contained a repeated sequence that could be learned implicitly and random sequences that could not. On a separate fifth day, a retention test was performed to assess implicit sequence-specific motor learning of the task. Tracking error was decreased for the group who received 1 Hz rTMS over the PMd during the early consolidation period immediately following practice compared with control or 5 Hz rTMS. Enhanced sequence-specific learning with 1 Hz rTMS following practice was due to greater offline consolidation, not differences in online learning between the groups within practice days. A follow-up experiment revealed that stimulation of PMd following practice did not differentially change motor cortical excitability, suggesting that changes in offline consolidation can be largely attributed to stimulation-induced changes in PMd. These findings support a differential role for the PMd in support of online and offline sequence-specific learning of a visuomotor task and offer converging evidence for competing memory systems.
authors.affiliation: School of Kinesiology, University of Michigan, Ann Arbor, MI, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Meehan
authors.affiliation: Department of Physical Therapy, University of British Columbia, Vancouver, BC, Canada.
authors.forename: J R
authors.initials: JR
authors.lastname: Zabukovec
authors.affiliation: Department of Physical Therapy, University of British Columbia, Vancouver, BC, Canada.
authors.forename: E
authors.initials: E
authors.lastname: Dao
authors.affiliation: Department of Physical Therapy, University of British Columbia, Vancouver, BC, Canada.
authors.forename: K L
authors.initials: KL
authors.lastname: Cheung
authors.affiliation: Department of Physical Therapy, University of British Columbia, Vancouver, BC, Canada.
authors.forename: M A
authors.initials: MA
authors.lastname: Linsdell
authors.affiliation: Department of Physical Therapy, University of British Columbia, Vancouver, BC, Canada.|Brain Research Centre, University of British Columbia, 212-2177 Wesbrook Mall, Vancouver, BC, V6T 2B5, Canada.
authors.forename: L A
authors.initials: LA
authors.lastname: Boyd
mesh_terms: D000328:Adult; D001364:Awareness; D005260:Female; D006225:Hand; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D009048:Motor Skills / Q000502:physiology*; D012691:Serial Learning / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D055815:Young Adult
keywords: dorsal premotor cortex; implicit motor learning; offline motor learning; online motor learning; repetitive transcranial magnetic stimulation