The effect of coordination mode on use-dependent plasticity.
OBJECTIVE
To evaluate the role of coordination mode on the generation of use-dependent plasticity (UDP) within the primary motor cortex (M1).


METHODS
Ten healthy volunteers performed brisk repetitive thumb movements for 30 min in the opposite direction to those evoked by transcranial magnetic stimulation (TMS) prior to training. This practice was synchronized or syncopated with a 1 Hz auditory metronome in two separate sessions. Motor evoked potentials (MEPs) were recorded from 3 intrinsic thumb muscles, to assess changes in corticomotor excitability.


RESULTS
Both synchronized and syncopated motor practice induced changes in the direction of TMS-evoked thumb movements, away from the baseline direction toward the trained direction. MEP amplitude increased following synchronized, but not syncopated, motor practice. Changes in movement direction and corticomotor excitability lasted for at least 30 minutes.


CONCLUSIONS
UDP can be elicited in the presence or absence of changes in corticomotor excitability.


CONCLUSIONS
Motor practice that is synchronized with external pacing may promote UDP and facilitate corticomotor excitability in patient populations with reduced corticomotor output, such as stroke. Training that is syncopated with external pacing may promote UDP without increasing corticomotor excitability. This could be relevant for individuals with disorders characterized by maladaptive plasticity.
Ackerley
Suzanne J
SJ
Movement Neuroscience Laboratory, Department of Sport and Exercise Science, University of Auckland, Private Bag 92019, Auckland, New Zealand.
Stinear
Cathy M
CM
Byblow
Winston D
WD
D000161:Acoustic Stimulation; D000328:Adult; D004056:Differential Threshold; D004576:Electromyography; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D013933:Thumb; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation