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Corticospinal Excitability Modulation During Action Observation
Published on: December 31, 2013
Enhanced corticospinal excitability with physiologically heightened sympathetic nerve activity
Vasiliy E Buharin1, Andrew J Butler, Justin K Rajendra
1School of Applied Physiology, The Georgia Institute of Technology, Atlanta, Georgia 30332-0356, USA.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|December 15, 2012
Summary
Heightened sympathetic nerve activity, induced by lower body negative pressure (LBNP), enhances corticospinal excitability in humans. This finding reveals a direct link between sympathetic responses and motor control pathways.
Area of Science:
- Neuroscience
- Human Physiology
- Motor Control
Background:
- Norepinephrine and dopamine agonists differentially modulate corticospinal excitability.
- Both monoamines are released during heightened sympathetic nerve activity.
Purpose of the Study:
- To investigate the effect of physiologically heightened sympathetic nerve activity on corticospinal excitability in healthy humans.
Main Methods:
- Participants underwent two transcranial magnetic stimulation (TMS) trials measuring motor-evoked potentials (MEPs) from the first dorsal interosseous muscle.
- The experimental group experienced heightened sympathetic nerve activity via lower body negative pressure (LBNP) during the second trial.
- The control group had no alteration in sympathetic nerve activity between trials.
Main Results:
- MEP peak-to-peak amplitude significantly increased from trial 1 to trial 2 in the experimental group only.
- This enhancement in corticospinal excitability was observed at TMS intensities of 130% resting motor threshold and higher.
Conclusions:
- Physiological heightening of sympathetic nerve activity using LBNP enhances corticospinal excitability.
- This suggests a direct modulatory role of sympathetic outflow on the human motor cortex.
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