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Updated: Aug 13, 2026

Corticospinal Excitability Modulation During Action Observation
Published on: January 1, 2014
Different ipsilateral representations for distal and proximal movements in the sensorimotor cortex: activation and
A C Nirkko1, C Ozdoba, S M Redmond
1Department of Neurology, University of Berne, Inselspital, Berne, Switzerland.
The dominant hemisphere controls the ipsilateral arm, with secondary motor areas crucial for distal movements and both primary and secondary areas for proximal movements.
Area of Science:
- Neuroscience
- Motor Control
- Human Neuroimaging
Background:
- Hemispheric control of the ipsilateral arm shows dominance asymmetry.
- The specific roles of primary and secondary motor areas in ipsilateral control remain unclear.
Purpose of the Study:
- To differentiate the contributions of primary and secondary motor areas to ipsilateral arm control.
- To investigate motor control during discrete unilateral distal finger and proximal shoulder movements.
Main Methods:
- Whole-brain functional magnetic resonance imaging (fMRI) in healthy human subjects.
- Analysis of brain activation patterns during specific arm movements.
Main Results:
- Ipsilateral distal movements selectively activated secondary motor areas, sparing primary sensorimotor cortex (SM1).
- Ipsilateral proximal movements activated both SM1 and secondary motor areas.
- A distinct precentral gyrus territory showed secondary motor area activation patterns.
- Hemispheric dominance effects were linked exclusively to secondary motor areas.
Conclusions:
- Secondary motor areas play a significant role in ipsilateral arm control, particularly for distal movements.
- Primary and secondary motor areas collaborate in ipsilateral proximal arm control.
- Findings align with functional demands and existing neurophysiological data.
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