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Type: Journal article
Title: Age-related differences in corticospinal control during functional isometric contractions in left and right hands
Author: Sale, M.
Semmler, J.
Citation: Journal of Applied Physiology, 2005; 99(4):1483-1493
Publisher: Amer Physiological Soc
Issue Date: 2005
ISSN: 8750-7587
Statement of
Martin V. Sale and John G. Semmler
Abstract: The purpose of the study was to examine age-related differences in electromyographic (EMG) responses to transcranial magnetic stimulation (TMS) during functional isometric contractions in left and right hands. EMG responses were recorded from the first dorsal interosseus muscle following TMS in 10 young (26.6 +/- 1.3 yr) and 10 old (67.6 +/- 2.3 yr) right-handed subjects. Muscle evoked potentials (MEPs) and silent-period durations were obtained in the left and right hands during index finger abduction, a precision grip, a power grip, and a scissor grip, while EMG was held constant at 5% of maximum. For all tasks, MEP area was 30% (P < 0.001) lower in the left hand of old compared with young subjects, whereas there was no age difference in the right hand. The duration of the EMG silent period was 14% (P < 0.001) shorter in old (150.3 +/- 2.9 ms) compared with young (173.9 +/- 3.0 ms) subjects, and the age differences were accentuated in the left hand (19% shorter, P < 0.001). For all subjects, the largest MEP area (10-12% larger) and longest EMG silent period (8-19 ms longer) were observed for the scissor grip compared with the other three tasks, and the largest task-dependent change in these variables was observed in the right hand of older adults. These differences in corticospinal control in the left and right hands of older adults may reflect neural adaptations that occur throughout a lifetime of preferential hand use for skilled (dominant) and unskilled (nondominant) motor tasks.
Keywords: aging; transcranial magnetic stimulation; hand function; motor cortex; electromyography
Description: Copyright © 2005 by the American Physiological Society.
RMID: 0020063355
DOI: 10.1152/japplphysiol.00371.2005
Appears in Collections:Molecular and Biomedical Science publications

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