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Reduced SMA‐M1 connectivity in older than younger adults measured using dual‐site TMS

Rurak, B.K., Rodrigues, J.P., Power, B.D., Drummond, P.D.ORCID: 0000-0002-3711-8737 and Vallence, A.M.ORCID: 0000-0001-9190-6366 (2021) Reduced SMA‐M1 connectivity in older than younger adults measured using dual‐site TMS. European Journal of Neuroscience . Early View.

Link to Published Version: https://doi.org/10.1111/ejn.15438
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Abstract

With advancing age comes a decline in voluntary movement control. Growing evidence suggests that an age-related decline in effective connectivity between the supplementary motor area and primary motor cortex (SMA-M1) might play a role in an age-related decline of bilateral motor control. Dual-site transcranial magnetic stimulation (TMS) can be used to measure SMA-M1 effective connectivity. In the current study, we aimed to (1) replicate previous dual-site TMS research showing reduced SMA-M1 connectivity in older than younger adults and (2) examine whether SMA-M1 connectivity is associated with bilateral motor control in independent samples of younger (n = 30) and older adults (n = 30). SMA-M1 connectivity was measured using dual-site TMS with interstimulus intervals of 6, 7 and 8 ms, and bilateral motor control was measured using the Purdue Pegboard, Four Square Step Test and the Timed Up and Go task. Findings from this study showed that SMA-M1 connectivity was reduced in older than in younger adults, suggesting that the direct excitatory connections between SMA and M1 had reduced efficacy in older than younger adults. Furthermore, greater SMA-M1 connectivity was associated with better bimanual motor control in older adults. Thus, SMA-M1 connectivity in older adults might underpin, in part, the age-related decline in bilateral motor control. These findings contribute to our understanding of age-related declines in motor control and provide a physiological basis for the development of interventions to improve bimanual and bilateral motor control.

Item Type: Journal Article
Murdoch Affiliation(s): Psychology, Counselling, Exercise Science and Chiropractic
Centre for Healthy Ageing
Centre for Molecular Medicine and Innovative Therapeutics (CMMIT)
Health Futures Institute
Publisher: Wiley
Copyright: © 2021 Federation of European Neuroscience Societies and John Wiley & Sons Ltd
URI: http://researchrepository.murdoch.edu.au/id/eprint/62257
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