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Role of the Ipsilateral Primary Motor Cortex in Controlling the Timing of Hand Muscle Recruitment

Role of the Ipsilateral Primary Motor Cortex in Controlling the Timing of Hand Muscle Recruitment The precise contribution of the ipsilateral primary motor cortex (iM1) to hand movements remains controversial. To address this issue, we elicited transient virtual lesions of iM1 by means of transcranial magnetic stimulation (TMS) in healthy subjects performing either a grip-lift task or a step-tracking task with their right dominant hand. We found that, irrespective of the task, a virtual lesion of iM1 altered the timing of the muscle recruitment. In the grip-lift task, this led to a less coordinated sequence of grip and lift movements and in the step-tracking task, to a perturbation of the movement trajectory. In the step-tracking task, we have demonstrated that disrupting iM1 activity may, depending on the TMS delay, either advance or delay the muscle recruitment. The present study suggests that iM1 plays a critical role in hand movements by contributing to the setting of the muscle recruitment timing, most likely through either inhibitory or facilitatory transcallosal influences onto the contralateral M1 (cM1). iM1 would therefore contribute to shape precisely the muscular command originating from cM1. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Cerebral Cortex Oxford University Press

Role of the Ipsilateral Primary Motor Cortex in Controlling the Timing of Hand Muscle Recruitment

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References (78)

Publisher
Oxford University Press
Copyright
The Author 2006. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: [email protected]
ISSN
1047-3211
eISSN
1460-2199
DOI
10.1093/cercor/bhj152
pmid
16525129
Publisher site
See Article on Publisher Site

Abstract

The precise contribution of the ipsilateral primary motor cortex (iM1) to hand movements remains controversial. To address this issue, we elicited transient virtual lesions of iM1 by means of transcranial magnetic stimulation (TMS) in healthy subjects performing either a grip-lift task or a step-tracking task with their right dominant hand. We found that, irrespective of the task, a virtual lesion of iM1 altered the timing of the muscle recruitment. In the grip-lift task, this led to a less coordinated sequence of grip and lift movements and in the step-tracking task, to a perturbation of the movement trajectory. In the step-tracking task, we have demonstrated that disrupting iM1 activity may, depending on the TMS delay, either advance or delay the muscle recruitment. The present study suggests that iM1 plays a critical role in hand movements by contributing to the setting of the muscle recruitment timing, most likely through either inhibitory or facilitatory transcallosal influences onto the contralateral M1 (cM1). iM1 would therefore contribute to shape precisely the muscular command originating from cM1.

Journal

Cerebral Cortex – Oxford University Press

Published: Mar 8, 2006

Keywords: agonist–antagonist muscles corpus callosum interhemispheric inhibition motor cortex TMS

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