Motor learning and cross-limb transfer rely upon distinct neural adaptation processes

Stoeckel, Tino, Carroll, Timothy J., Summers, Jeffery J. and Hinder, Mark R. (2016) Motor learning and cross-limb transfer rely upon distinct neural adaptation processes. Journal of Neurophysiology, 116 2: 575-586. doi:10.1152/jn.00225.2016

Author Stoeckel, Tino
Carroll, Timothy J.
Summers, Jeffery J.
Hinder, Mark R.
Title Motor learning and cross-limb transfer rely upon distinct neural adaptation processes
Journal name Journal of Neurophysiology   Check publisher's open access policy
ISSN 1522-1598
Publication date 2016-08-01
Year available 2016
Sub-type Article (original research)
DOI 10.1152/jn.00225.2016
Open Access Status Not yet assessed
Volume 116
Issue 2
Start page 575
End page 586
Total pages 12
Place of publication Bethesda, MD United States
Publisher American Physiological Society
Language eng
Subject 2800 Neuroscience
1314 Physiology
Abstract Performance benefits conferred in the untrained limb after unilateral motor practice are termed cross-limb transfer. Although the effect is robust, the neural mechanisms remain incompletely understood. In this study we used noninvasive brain stimulation to reveal that the neural adaptations that mediate motor learning in the trained limb are distinct from those that underlie cross-limb transfer to the opposite limb. Thirty-six participants practiced a ballistic motor task with their right index finger (150 trials), followed by intermittent theta-burst stimulation (iTBS) applied to the trained (contralateral) primary motor cortex (cM1 group), the untrained (ipsilateral) M1 (iM1 group), or the vertex (sham group). After stimulation, another 150 training trials were undertaken. Motor performance and corticospinal excitability were assessed before motor training, pre- and post-iTBS, and after the second training bout. For all groups, training significantly increased performance and excitability of the trained hand, and performance, but not excitability, of the untrained hand, indicating transfer at the level of task performance. The typical facilitatory effect of iTBS on MEPs was reversed for cM1, suggesting homeostatic metaplasticity, and prior performance gains in the trained hand were degraded, suggesting that iTBS interfered with learning. In stark contrast, iM1 iTBS facilitated both performance and excitability for the untrained hand. Importantly, the effects of cM1 and iM1 iTBS on behavior were exclusive to the hand contralateral to stimulation, suggesting that adaptations within the untrained M1 contribute to cross-limb transfer. However, the neural processes that mediate learning in the trained hemisphere vs. transfer in the untrained hemisphere appear distinct.
Keyword Ballistic motor learning
Interlimb transfer
Noninvasive brain stimulation
Corticospinal excitability
Motor performance
Q-Index Code C1
Q-Index Status Provisional Code
Grant ID APP1050261
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
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