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Hemispheric differences in the relationship between corticomotor excitability changes following a fine-motor task and motor learning

journal contribution
posted on 2023-05-16, 16:46 authored by Michael GarryMichael Garry, Kamen, G, Nordstrom, MA
Motor performance induces a postexercise increase in corticomotor excitability that may be associated with motor learning. We investigated whether there are hemispheric differences in the extent and/or time course of changes in corticomotor excitability following a manipulation task (Purdue pegboard) and their relationship with motor performance. Single- and paired-pulse (3 ms) transcranial magnetic stimulation (TMS) was used to assess task-induced facilitation of the muscle evoked potential (MEP) and intracortical inhibition (ICI) for three intrinsic hand muscles acting on digits 1, 2, and 5. Fifteen right-handed subjects performed three 30-s pegboard trials with left or right hand in separate sessions. TMS was applied to contralateral motor cortex before and after performance. Number of pegs placed was higher with the right hand, and performance improved (motor learning) with both hands over the three trials. MEP facilitation following performance was short-lasting (<15 min), selective for muscles engaged in gripping the pegs, and of similar magnitude in left and right hands, ICI was reduced immediately following performance with the right hand, but not the left. The extent of MEP facilitation was positively correlated with motor learning for the right hand only. We conclude that the pegboard task induces a selective, short-lasting change in excitability of corticospinal neurons controlling intrinsic hand muscles engaged in the task. Only left hemisphere changes were related to motor learning. This asymmetry may reflect different behavioral strategies for performance improvement with left and right upper limb in this task or hemispheric differences in the control of skilled hand movements.

History

Publication title

Journal of Neurophysiology

Volume

91

Issue

4

Pagination

1570-1578

ISSN

0022-3077

Department/School

School of Psychological Sciences

Publisher

American Physiological Society

Place of publication

USA

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in philosophy and religious studies

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