Stinear Cathy M, Fleming Melanie K, Byblow Winston D
Human Motor Control Laboratory, Dept Sport and Exercise Science, University of Auckland, Auckland, New Zealand, Private Bag 92019, Auckland, New Zealand.
Brain Res. 2006 Jun 20;1095(1):139-47. doi: 10.1016/j.brainres.2006.04.008. Epub 2006 May 19.
Most studies of motor imagery have examined motor cortex function during imagery of dominant hand movement. The aim of this study was to examine the modulation of excitability in the dominant and non-dominant corticomotor pathways during kinesthetic motor imagery of unimanual and bimanual movement. Transcranial magnetic stimulation (TMS) was applied over the contralateral motor cortex (M1) to elicit motor-evoked potentials (MEPs) in the abductor pollicis brevis (APB) and abductor digiti minimi (ADM) muscles of each hand, in two separate sessions. Transcutaneous electrical stimuli were also delivered to the median nerve at each wrist, to elicit F-waves from APB. Fifteen right-handed volunteers imagined unimanual and bimanual phasic thumb movements, paced with a 1-Hz auditory metronome. Stimuli were delivered at rest, and either 50 ms before (ON phase), or 450 ms after (OFF phase), the metronome beeps. Significant MEP amplitude facilitation occurred only in right APB, during the ON phase of motor imagery of the right hand and both hands. Significant temporal modulation of right APB MEP amplitude was observed during motor imagery of right, left and bimanual performance. F-wave persistence and amplitude were unaffected by imagery. These results demonstrate that the motor imagery is lateralized to the left (dominant) hemisphere, which is engaged by imagery of each hand separately, and bimanual imagery. This finding has implications for the use of motor imagery in rehabilitation.
大多数运动想象研究都考察了优势手运动想象过程中的运动皮层功能。本研究的目的是在单手动和双手运动的动觉运动想象过程中，检测优势和非优势皮质运动通路兴奋性的调节情况。在两个独立的实验环节中，通过经颅磁刺激（TMS）作用于对侧运动皮层（M1），以诱发每只手的拇短展肌（APB）和小指展肌（ADM）的运动诱发电位（MEP）。还对每个手腕的正中神经施加经皮电刺激，以引出APB的F波。15名右利手志愿者想象单手动和双手的拇指阶段性运动，并与1赫兹的听觉节拍器同步。在静息状态下以及在节拍器发出哔哔声前50毫秒（开启阶段）或后450毫秒（关闭阶段）施加刺激。仅在右手和双手运动想象的开启阶段，右APB中出现了显著的MEP波幅易化。在右手、左手和双手运动表现的运动想象过程中，观察到右APB的MEP波幅存在显著的时间调制。F波的持续性和波幅不受想象的影响。这些结果表明，运动想象定位于左侧（优势）半球，该半球分别参与每只手以及双手的运动想象。这一发现对运动想象在康复中的应用具有启示意义。
