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Updated: Jul 18, 2026
An Experiment Using Functional Near-Infrared Spectroscopy and Robot-Assisted Multi-Joint Pointing Movements of the Lower Limb
Published on: June 7, 2024
Ipsilateral motor activation during unimanual and bimanual motor tasks
Georges A Ghacibeh1, Ravi Mirpuri, Valeria Drago
1University of Florida, Department of Neurology, P.O. Box 100236, Gainesville, FL 32610, USA. ghacig@neurology.ufl.edu
Objective:
To test for the presence and possible asymmetry of ipsilateral motor activation during unimanual and bimanual motor tasks.
Methods:
Twelve right-handed healthy subjects underwent motor evoked potential (MEP) measurement of one hand (target-hand) while the other hand (task-hand) performed different motor tasks. The target-hand was either at rest (first experiment) or performed a Perdue PegBoard task (second experiment). The task-hand was either at rest, performed a simultaneous pegboard task, or rotated a coin (second experiment).
Results:
In the first experiment, the motor task resulted in significant increase in MEP area in the target-hand, regardless which hand was the task-hand, with a greater increase when the left hand was the task-hand. In the second experiment, ipsilateral motor activation was not present for either hand, however, when the right hand was the task-hand, performance of continuous coin rotation by the right hand resulted in a significant decrease in the MEP area of the left hand.
Conclusions:
Hemispheric asymmetry and task-dependence of ipsilateral motor cortex activation supports the postulate that motor activity may start bilaterally with subsequent interhemispheric inhibition. Furthermore, in right-handers, the left motor cortex is either more active in ipsilateral hand movements or exerts more effective inhibitory control over the right motor cortex than vice versa.
Significance:
We suggest that hemispheric asymmetry in ipsilateral motor control is a factor in determining motor dominance in right-handed individuals.
