Citation

Hinder MR, Carroll TJ, Summers JJ. J. Neurophysiol. 2013; 109(12): 2963-2971.

Affiliation

1University of Tasmania.

Copyright

(Copyright © 2013, American Physiological Society)

DOI

10.1152/jn.00535.2012

PMID

23536709

Abstract

Bilateral movement rehabilitation is gaining popularity as an approach not only to improve the recovery of bimanual function, but also of unilateral motor tasks. While the neural mechanisms mediating the transfer of bilateral training gains into unimanual contexts are not fully understood, converging evidence from behavioural, neurophysiological and imaging studies suggests that bimanual movements are not simply the superposition of unimanual tasks undertaken with both (upper) limbs. Here we investigated the neural responses in both hemispheres to bilateral ballistic motor training, and the extent to which performance improvements transferred to a unimanual task. Since aging influences interhemispheric interactions during movement production, both young (n=9; mean age 19.4 years; 6 female) and older (n=9; 66.3 years; 7 female) adults practiced a bilateral motor task requiring simultaneous 'fast-as-possible' abductions of their left and right index fingers. Changes in bilateral and unilateral performance, and in corticospinal excitability and intracortical inhibition, were assessed. Strong transfer was observed between bimanual and unimanual contexts for both age groups. However, in contrast to previous reports of substantial bilateral cortical adaptations following unilateral training, increases in corticospinal excitability following bilateral training were not statistically reliable, and a release of intracortical inhibition was only observed for older adults. The results indicate that the neural mechanisms of motor learning for bilateral ballistic tasks differ from those that underlie unimanual ballistic performance improvement, but that ageing results in a greater overlap of the neural mechanisms mediating bilateral and unilateral ballistic motor performance.

Language: en