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Updated: Aug 9, 2026

Corticospinal Excitability Modulation During Action Observation
Published on: December 31, 2013
Motor cortex excitability during ballistic forearm and finger movements
1Clinical Neurophysiology Unit, University Department of Clinical Neurology, The Radcliffe Infirmary, Oxford, United Kingdom.
Ballistic movements like forearm flexion and finger abduction show different electromyogram (EMG) patterns. However, cortical excitability suggests a similar underlying motor program for both actions.
Area of Science:
- Neuroscience
- Motor Control
- Human Movement Science
Background:
- Electromyogram (EMG) patterns differ significantly between ballistic forearm flexion (triphasic biceps, single triceps bursts) and rapid index finger abduction (single agonist burst).
- Understanding the neural control mechanisms underlying these distinct movement patterns is crucial for motor control research.
Purpose of the Study:
- To investigate and compare cortical and spinal cord excitability during self-paced ballistic forearm and index finger movements.
- To explore potential similarities in the central motor programs despite differing EMG patterns.
Main Methods:
- Utilized transcranial magnetic and electrical stimulation triggered at the onset of EMG bursts.
- Probed motor cortical and spinal cord excitability during ballistic forearm flexion and index finger abduction.
- Analyzed electromyogram (EMG) patterns and evoked cortical responses.
Main Results:
- A triphasic EMG pattern was observed in forearm flexion (biceps/triceps), contrasting with a single agonist burst for finger abduction.
- Cortical excitability showed distinct phases related to EMG bursts in both movements.
- Notably, increased motor cortical excitability during finger abduction was not directly correlated with any concurrent EMG activity.
Conclusions:
- Despite divergent EMG patterns, the underlying central motor program for ballistic forearm flexion and index finger abduction may share similarities.
- Motor cortical excitability dynamics provide insights into the neural control of voluntary movements, even when not directly coupled to muscle activity.
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