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Corticospinal Excitability Modulation During Action Observation
Published on: December 31, 2013
Expectancy induces dynamic modulation of corticospinal excitability.
Gijs van Elswijk1, Bert U Kleine, Sebastiaan Overeem
1Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. gijs@vanelswijk.net
Journal of Cognitive Neuroscience
|January 12, 2007
Summary
Increased expectancy of a response signal shortens reaction times (RTs) and modulates corticospinal excitability. This suggests expectancy influences motor preparation through direct changes in the corticospinal system, not just interneurons.
Area of Science:
- Neuroscience
- Motor Control
- Human Motor Performance
Background:
- Behavioral studies show expectancy shortens reaction times (RTs).
- Neurophysiological data suggest expectancy modulates motor structure activity.
- The direct impact of expectancy on corticospinal excitability remains unclear.
Purpose of the Study:
- To investigate if response signal expectancy modulates corticospinal system excitability.
- To determine the relationship between expectancy, RT, and corticospinal excitability.
Main Methods:
- Combined single- and paired-pulse transcranial magnetic stimulation (TMS) over the primary motor cortex.
- Utilized a simple reaction time task with variable preparatory delays.
- Measured changes in corticospinal excitability in relation to response signal expectancy.
Main Results:
- RTs decreased as response signal expectancy increased.
- Corticospinal excitability was modulated by response signal expectancy.
- Excitability increased over preparatory delays and transiently when a signal was expected.
- Paired-pulse TMS indicated modulation is unlikely due to M1 interneurons.
Conclusions:
- Response signal expectancy directly modulates corticospinal excitability.
- This modulation occurs independently of changes in primary motor cortex interneuronal networks.
- Mechanisms like corticospinal synchronization or spinal circuit changes may mediate this effect.
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