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    Similar scaling of contralateral and ipsilateral cortical responses during graded unimanual force generation

    Derosiere, Gerard and Alexandre, F. and Bourdillon, N. and Mandrick, K. and Ward, Tomas E. and Perrey, S. (2014) Similar scaling of contralateral and ipsilateral cortical responses during graded unimanual force generation. NeuroImage, 85 (1). pp. 471-477. ISSN 1053-8119

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    Hemibody movements are strongly considered as being under the control of the contralateral hemisphere of the cerebral cortex. However, some neuroimaging studies have found a bilateral activation of either the pri- mary sensori-motor (SM1) areas or the rostral prefrontal cortex (PFC), during unimanual tasks. More than just bilateral, the activation of these areas was found to be symmetrical in some studies. However, the sym- metrical response remains strongly controversial notably for handgrip force generations. We therefore aimed to examine the bilateral SM1 and rostral PFC area activations in response to graded submaximal force gener- ation during a unilateral handgrip task. Fifteen healthy subjects performed 6 levels of force (ranging from 5 to 50% of MVC) during a handgrip task. We concomitantly measured the activation of bilateral SM1 and rostral PFC areas through near-infrared spectroscopy (NIRS) and the electromyographic (EMG) activity of the bilat- eral fl exor digitorum super fi cialis (FDS) muscles. Symmetrical activation was found over the SM1 areas for all the investigated levels of force. At the highest level of force (i.e., 50% of MVC), the EMG of the passive FDS increased signi fi cantly and the ipsilateral rostral PFC activation was found more intense than the correspond- ing contralateral rostral PFC activation. We suggest that the visuo-guided control of force levels during a handgrip task requires the cross-talk from ipsi- to contralateral SM1 to cope for the relative complexity of the task, similar to that which occurs during complex sequential fi nger movement. We also propose alterna- tive explanations for the observed symmetrical SM1 activation including (i) the ipsilateral corticospinal tract and (ii) interhemispheric inhibition (IHI) mechanism. The increase in EMG activity over the passive FDS could be associated with a release of IHI at 50% of MVC. Finally, our results suggest that the greater ipsilateral (right) rostral PFC activation may re fl ect the greater demand of attention required to control the motor out- put at high levels of force

    Item Type: Article
    Keywords: NIRS; Cortical activation; Muscle force; Ipsilateral; Handgrip; Unimanual task;
    Academic Unit: Faculty of Science and Engineering > Electronic Engineering
    Item ID: 9268
    Identification Number:
    Depositing User: Dr Tomas Ward
    Date Deposited: 20 Feb 2018 17:27
    Journal or Publication Title: NeuroImage
    Publisher: Elsevier
    Refereed: Yes
    Use Licence: This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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