Remote effects on corticospinal excitability during motor execution and motor imagery.

We investigated the remote effect on corticospinal excitability of resting left and right hand muscles during motor execution and motor imagery when performing left or right foot plantar flexion. Fifteen right-handed subjects performed two conditions with three tasks: Condition (Motor Execution (ME) vs. Motor Imagery (MI)): Task (Control, Ipsilateral, and Contralateral). From the left and right first dorsal interosseous, motor evoked potentials (MEPs) elicited by a single-pulse transcranial magnetic stimulation (TMS) to the left or right primary motor cortices (M1) were recorded under all six trials. MEP amplitudes were significantly larger under the ME than MI condition, irrespective of hands and tasks. MEP amplitudes were also the largest during the Contralateral tasks, irrespective of the condition and hands. The correlation analysis showed that MEP amplitudes were significantly correlated between ME and MI conditions with both left and right hands. Our results indicate that the magnitude of the remote effect on corticospinal excitability of hand muscles differs between motor execution and motor imagery, and between ipsi- and contralateral limbs, when performing foot plantar flexion.
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