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Corticomotor excitability during a choice-hand reaction time task.
Steven McMillan1, Richard B Ivry, Winston D Byblow
1Human Motor Control Laboratory, Department of Sport and Exercise Science, University of Auckland, Tamaki Campus, Auckland, New Zealand.
Experimental Brain Research
|January 21, 2006
Summary
Cortico-motor excitability preparation for hand movements is influenced by both the specific muscle (flexion/extension) and the responding hand. The left hemisphere shows goal-based preparation for directional hand movements.
Area of Science:
- Neuroscience
- Motor Control
- Cognitive Neuroscience
Background:
- Motor preparation involves complex neural processes.
- Transcranial magnetic stimulation (TMS) is a tool to probe cortico-motor excitability.
Purpose of the Study:
- To investigate how directional cues and hand choice influence motor preparation.
- To examine cortico-motor excitability changes during a reaction time task.
Main Methods:
- Healthy subjects performed a choice-hand reaction time task with wrist flexion/extension.
- Focal TMS was applied over hand motor areas during foreperiod and reaction time intervals.
- Corticomotor excitability was measured via electromyography.
Main Results:
- Increased cortico-motor excitability was observed in the agonist of the responding hand.
- Directional cues modulated excitability, with a direction-specific effect in the left hemisphere for left-hand movements.
- Homologous muscle activation and directional constraints influenced non-responding hand excitability.
Conclusions:
- Motor preparation involves both homologous muscle activation and directional goal-based processes.
- The left hemisphere exhibits unique directional preparation independent of the responding hand.
- These findings enhance understanding of neural mechanisms underlying motor control.