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Unilateral contractions modulate interhemispheric inhibition most strongly and most adaptively in the homologous muscle of the contralateral limb


Hinder, MR and Schmidt, M and Garry, MI and Summers, JJ, Unilateral contractions modulate interhemispheric inhibition most strongly and most adaptively in the homologous muscle of the contralateral limb, Experimental Brain Research, 205, (3) pp. 423-433. ISSN 0014-4819 (2010) [Refereed Article]

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DOI: doi:10.1007/s00221-010-2379-z


We investigated how volitional contractions affect interhemispheric inhibition (IHI) from the active to the passive hemisphere. Younger and older adults isometrically contracted their dominant thumb (abductor pollicis brevis, APB) to various force targets. In ballistic contraction trials, transcranial magnetic stimulation (TMS) was administered very shortly after the onset of APB activity. In tonic contraction trials, TMS was delivered while the target force was maintained. In control trials both thumbs remained quiescent. In all trials, a test stimulus (TS) was directed to the APB hotspot in the non-dominant hemisphere (130% left APB resting motor threshold, RMT). In half the trials, a conditioning stimulus (130% right APB RMT) was applied to the APB hotspot in the dominant hemisphere 10 ms prior to the TS. Targeted ballistic contractions of the right APB were found to modulate (increase) IHI measured in the left APB, as previously reported for tonic contractions. Furthermore, the extent of the IHI increase was found to scale with the strength of the contralateral ballistic or tonic contraction. Less pronounced, but statistically significant, IHI increases were also observed in the left abductor digiti minimi and extensor carpi radialis during right APB contraction. For these muscles, however, the extent of the IHI modulation was independent of APB contraction strength. The capacity to modulate inhibition during contractions was unaffected by advancing age. During volitional actions, the ability to modulate IHI most adaptively in the homologous muscle of the resting limb may contribute to the prevention of mirror movements.

Item Details

Item Type:Refereed Article
Keywords:Interhemispheric inhibition - Voluntary movement - Transcranial magnetic stimulation - Motor cortex - Ageing
Research Division:Psychology
Research Group:Cognitive and computational psychology
Research Field:Sensory processes, perception and performance
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in psychology
UTAS Author:Hinder, MR (Associate Professor Mark Hinder)
UTAS Author:Schmidt, M (Mr Matthew Schmidt)
UTAS Author:Garry, MI (Associate Professor Michael Garry)
UTAS Author:Summers, JJ (Professor Jeffery Summers)
ID Code:65105
Year Published:2010
Web of Science® Times Cited:54
Deposited By:Psychology
Deposited On:2010-10-04
Last Modified:2014-12-05

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