Contributions of the motor cortex to adaptive control of reaching depend on the perturbation schedule

Jean Jacques Orban De Xivry, Sarah E. Criscimagna-Hemminger, Reza Shadmehr

Research output: Contribution to journalArticlepeer-review


During adaptation, motor commands tend to repeat as performance plateaus. It has been hypothesized that this repetition produces plasticity in the motor cortex (M1). Here, we considered a force field reaching paradigm, varied the perturbation schedule to potentially alter the amount of repetition, and quantified the interaction between disruption of M1 using transcranial magnetic stimulation (TMS) and the schedule of perturbations. In the abrupt condition (introduction of the perturbation on a single trial followed by constant perturbation), motor output adapted rapidly and was then followed by significant repetition as performance plateaued. TMS of M1 had no effect on the rapid adaptation phase but reduced adaptation at the plateau. In the intermediate condition (introduction of the perturbation over 45 trials), disruption of M1 had no effect on the phase in which motor output changed but again impaired adaptation when performance had plateaued. Finally, when the perturbation was imposed gradually (over 240 trials), the motor commands continuously changed during adaptation and never repeated, and disruption of M1 had no effect on performance. Therefore, TMS of M1 appeared to reduce adaptation of motor commands during a specific phase of learning: when motor commands tended to repeat.

Original languageEnglish (US)
Pages (from-to)1475-1484
Number of pages10
JournalCerebral Cortex
Issue number7
StatePublished - Jul 2011


  • force-field adaptation
  • motor control
  • primary motor cortex
  • repetition-dependent plasticity
  • transcranial magnetic stimulation

ASJC Scopus subject areas

  • Cognitive Neuroscience
  • Cellular and Molecular Neuroscience

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