Competition for limited neural resources in older adults leads to greater asymmetry of bilateral movements than in young adults

Elizabeth J Woytowicz, Robert L Sainburg, Kelly P Westlake, Jill Whitall

Research output: Contribution to journalArticle

Abstract

We previously demonstrated that lateralization in the neural control of predictive and impedance mechanisms is reflected by interlimb differences in control of bilateral tasks. Aging has been shown to reduce lateralization during unilateral performance, presumably due to greater recruitment of the ipsilateral hemisphere. We now hypothesize that aging-related reduction in neural resources should produce greater behavioral asymmetry during bilateral actions that require hemispheric specialization for each arm. This is because simultaneous control of dominant and non-dominant arm function should induce competition for hemisphere-specific resources. To test this hypothesis, we now examine the effect of aging (young, N=20; old, N=20) on performance of a mechanically coupled task, in which one arm reaches toward targets while the other arm stabilizes against a spring that connects the two arms. Results indicate better dominant arm reaching performance and better non-dominant arm stabilizing performance for both groups. Most notably, limb and joint compliance was lower in the dominant arm, leading to dominant arm deficits in stabilizing performance. Group analysis indicated that older adults showed substantially greater asymmetry in stabilizing against the spring load than did the younger adults. We propose that competition for limited neural resources in older adults is associated with reduced contributions of right hemisphere mechanisms to right-dominant arm stabilizing performance, and thus to greater asymmetry of performance.

Original languageEnglish (US)
JournalJournal of neurophysiology
DOIs
StateE-pub ahead of print - Jan 8 2020
Externally publishedYes

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