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Motor demand-dependent activation of ipsilateral motor cortex
Cathrin M Buetefisch1, Kate Pirog Revill2, Linda Shuster3
1Department. of Neurology, West Virginia University, Morgantown, West Virginia; Department of Physiology, West Virginia University, Morgantown, West Virginia; Department of Neurology, Emory University, Atlanta, Georgia; Department of Rehabilitation Medicine, Emory University, Atlanta, Georgia; and cathrin.m.buetefisch@emory.edu.
Journal of Neurophysiology
|May 23, 2014
Summary
Ipsilateral primary motor cortex (M1) is active during unilateral hand tasks. Its activity increases with greater precision demands, suggesting a role in fine motor control.
Area of Science:
- Neuroscience
- Motor Control
- Neuroimaging
Background:
- The role of the ipsilateral primary motor cortex (M1) in unilateral hand motor control is debated.
- Previous functional magnetic resonance imaging (fMRI) studies show inconsistent bilateral M1 activation.
- Task differences and lack of movement verification limit interpretations of M1's role.
Purpose of the Study:
- To investigate if ipsilateral M1 activity during a unilateral hand task is dependent on the demand for precision.
- To examine M1 contributions when motor task difficulty is systematically varied.
Main Methods:
- Used fMRI and simultaneous EMG to study 13 healthy participants performing a unilateral pointing task with varying target sizes.
- Employed a clustered acquisition technique to ensure strictly unilateral movements.
- Analyzed brain activity in relation to task accuracy and precision demands.
Main Results:
- Confirmed activation in both contralateral and ipsilateral M1, extending to somatosensory and parietal areas.
- Observed significant differences in ipsilateral M1 activation, extending to the temporal/parietal junction.
- Found that ipsilateral M1 activity increased with higher precision demands (smaller target sizes).
Conclusions:
- Ipsilateral M1 is actively involved in unilateral motor execution.
- The degree of ipsilateral M1 engagement is modulated by the precision requirements of the task.
- Findings suggest a functional role for ipsilateral M1 in skilled hand movements.
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