title: Disruption of primary motor cortex before learning impairs memory of movement dynamics.
abstract: Although multiple lines of evidence implicate the primary motor cortex (M1) in motor learning, the precise role of M1 in the adaptation to novel movement dynamics and in the subsequent consolidation of a memory of those dynamics remains unclear. Here we used repetitive transcranial magnetic stimulation (rTMS) to dissociate the contribution of M1 to these distinct aspects of motor learning. Subjects performed reaching movements in velocity-dependent force fields over three epochs: a null-field baseline epoch, a clockwise-field learning epoch (15 min after the baseline epoch), and a clockwise-field retest epoch (24 h after the learning epoch). Half of the subjects received 15 min of 1 Hz rTMS to M1 between the baseline and learning epochs. Subjects given rTMS performed identically to control subjects during the learning epoch. However, control subjects performed with significantly less error than rTMS subjects in the retest epoch on the following day. These results suggest that M1 is not critical to the network supporting motor adaptation per se but that, within this network, M1 may be important for initiating the development of long-term motor memories.
authors.affiliation: Division of Health Sciences and Technology, Massachusetts Institute of Technology and Harvard Medical School, Cambridge, Massachusetts 02142, USA.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Richardson
authors.forename: Simon A
authors.initials: SA
authors.lastname: Overduin
authors.forename: Antoni
authors.initials: A
authors.lastname: Valero-Cabré
authors.forename: Camillo
authors.initials: C
authors.lastname: Padoa-Schioppa
authors.forename: Alvaro
authors.initials: A
authors.lastname: Pascual-Leone
authors.forename: Emilio
authors.initials: E
authors.lastname: Bizzi
authors.forename: Daniel Z
authors.initials: DZ
authors.lastname: Press
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006801:Humans; D007858:Learning / Q000502:physiology*; D008297:Male; D008568:Memory / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*