Decreased input to the motor cortex increases motor cortical excitability

被引:17
作者
Todd, Gabrielle
Butler, Jane E.
Gandevia, S. C. [1 ]
Taylor, Janet L.
机构
[1] Prince Wales Med Res Inst, Sydney, NSW 2031, Australia
[2] Univ New S Wales, Sydney, NSW 2031, Australia
[3] Univ Adelaide, Sch Mol & Biomed Sci, Discipline Physiol, Adelaide, SA 5005, Australia
基金
英国医学研究理事会;
关键词
afferents; motor evoked potential; transcranial magnetic stimulation; motor cortex; plasticity;
D O I
10.1016/j.clinph.2006.07.303
中图分类号
R74 [神经病学与精神病学];
学科分类号
摘要
Objective: To investigate whether a short-duration reduction of input to the motor cortex affects excitability in the hand region of the motor cortex. Methods: Subjects (n = 10) received sets of transcranial magnetic stimulation of the motor cortex (TMS) and peripheral ulnar nerve stimulation. Stimuli were delivered before and after 20 min of inactivity of the test hand. The evoked compound muscle action potentials were recorded in two relaxed intrinsic hand muscles using surface EMG. Results: Motor evoked potential size (MEP; expressed relative to the maximal M-wave) increased by similar to 30-40% in both hand muscles (P = 0.012) following inactivity. The enlarged MEP was not associated with changes in F-wave size, a marker of motoneurone excitability, or changes in intracortical inhibition and facilitation measured with paired-pulse TMS. Conclusions: MEP growth most likely reflects an increase in motor cortical excitability. The increased excitability appears to be more associated with reduced voluntary drive to and from the motor cortex rather than reduced afferent input from the periphery. Significance: These results have important implications for any investigation of motor cortical excitability in relaxed subjects. The outcome of an experimental intervention is the net result of the intervention itself and alterations in cortical excitability produced by the subjects' inactivity. (c) 2006 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.
引用
收藏
页码:2496 / 2503
页数:8
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