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The effect of ballistic thumb contractions on the excitability of the ipsilateral motor cortex


Hinder, MR and Schmidt, M and Garry, MI and Summers, JJ, The effect of ballistic thumb contractions on the excitability of the ipsilateral motor cortex, Experimental Brain Research, 201, (2) pp. 229-238. ISSN 0014-4819 (2010) [Refereed Article]

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DOI: doi:10.1007/s00221-009-2029-5


We investigated how ballistic contractions of the left thumb affect the excitability of the ipsilateral motor cortex using transcranial magnetic stimulation (TMS). TMS was applied at the motor hotspot for the right abductor pollicis brevis (APB) muscle. In ‘self-triggered’ trials, participants made targeted, isometric, contractions of the left APB. The right APB was either relaxed or maintained a tonic contraction. TMS was administered as soon as possible after electromyographic onset in the left APB. In ‘control’ trials, the left thumb remained quiescent and TMS was triggered by the computer. In each condition, 20–24 trials were conducted. Half these trials involved a single test stimulus, TS (130% APB resting motor threshold, RMT). In the other trials, short-interval intracortical inhibition (SICI) was investigated by applying a conditioning stimulus (70% APB RMT) 3 ms prior to the TS. SICI ratios were not significantly different in self-triggered and control trials. However, when the right APB was active, significantly shorter silent periods (SPs) were observed in self-triggered trials when compared with control trials. Our results support the view that SICI and SP are mediated by different inhibitory circuits, and that ipsilateral GABAB-ergic circuits (assessed by SP), but not GABAA-ergic circuits (assessed by SICI), are affected in the period immediately following voluntary ballistic contractions.

Item Details

Item Type:Refereed Article
Keywords:SICI - Inhibition - Movement - Silent period
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:60041
Year Published:2010
Web of Science® Times Cited:20
Deposited By:Psychology
Deposited On:2010-01-07
Last Modified:2014-12-18

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