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Age-related differences in corticospinal excitability and inhibition during coordination of upper and lower limbs

journal contribution
posted on 2023-05-17, 10:23 authored by Fujiyama, H, Mark HinderMark Hinder, Matthew SchmidtMatthew Schmidt, Michael GarryMichael Garry, Jeffery SummersJeffery Summers
The ability to coordinate upper and lower limbs—a prerequisite for many everyday activities—is known to decline with age. Here we report 2 experiments in which transcranial magnetic stimulation (TMS) was used to assess corticospinal excitatory and inhibitory processes in younger and older adults during cyclical hand-foot movements. In experiment 1, motor evoked potentials (MEP) and silent period (SP) durations were measured from the active right extensor carpi radialis (ECR) muscle while it executed rhythmic oscillations in conjunction with the right or left foot. Younger adults exhibited increased SP with ipsilateral limb combinations and decreased SP with contralateral limb combinations, relative to a baseline hand only condition. Strikingly, older adults exhibited a reduced SP when ipsilateral limbs moved in opposite directions. This effect was found to be most pronounced in those older adults who exhibited poor coordination performance, suggesting that the inability to regulate inhibitory processes may underlie age-related degradation of task performance. Experiment 2 examined motor evoked potentials and SP duration in the left extensor carpi radialis which maintained a tonic contraction while the coordination task was undertaken by the right arm and right or left foot. For younger adults, coordination of ipsilateral limbs was accompanied by increased inhibition in the ipsilateral motor cortex than during the coordination of contralateral limbs. No differences in SP between conditions were noted for the older adults. In summary, older adults’ reduced ability to coordinate upper and lower limbs may be related to the capacity to regulate inhibitory function in both hemispheres. This study suggests for the first time a direct link between age-related differences in interlimb coordination and the control of corticospinal inhibitory processes.

History

Publication title

Neurobiology of Aging

Volume

33

Issue

7

Pagination

1484.e1-1484.e14

ISSN

0197-4580

Department/School

School of Psychological Sciences

Publisher

Elsevier Inc

Place of publication

1600 John F Kennedy Blvd, Philadelphia 19103, USA

Rights statement

Copyright 2012 Elsevier Inc

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in psychology

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