TY - JOUR
T1 - Contributions of the motor cortex to adaptive control of reaching depend on the perturbation schedule
AU - Orban De Xivry, Jean Jacques
AU - Criscimagna-Hemminger, Sarah E.
AU - Shadmehr, Reza
N1 - Funding Information:
National Institutes of Health (NIH, NS37422); Belgian American Educational Foundation, internal research grant (Fonds Spéciaux de Recherche) of the Université catholique de Louvain (Belgium), Fondation pour la Vocation (Belgium) to J.J.O.d.X.; predoctoral fellowship from the NIH (NS062647 to S.E.C.-H.).
PY - 2011/7
Y1 - 2011/7
N2 - 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.
AB - 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.
KW - force-field adaptation
KW - motor control
KW - primary motor cortex
KW - repetition-dependent plasticity
KW - transcranial magnetic stimulation
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U2 - 10.1093/cercor/bhq192
DO - 10.1093/cercor/bhq192
M3 - Article
C2 - 21131448
AN - SCOPUS:79956192690
SN - 1047-3211
VL - 21
SP - 1475
EP - 1484
JO - Cerebral Cortex
JF - Cerebral Cortex
IS - 7
ER -