Stinear Cathy M, Byblow Winston D, Steyvers Maarten, Levin Oron, Swinnen Stephan P
Human Motor Control Laboratory, Department Sport & Exercise Science, University of Auckland, Private Bag 92019, Auckland, New Zealand.
Exp Brain Res. 2006 Jan;168(1-2):157-64. doi: 10.1007/s00221-005-0078-y. Epub 2005 Aug 3.
The hypothesis that motor imagery and actual movement involve overlapping neural structures in the central nervous system is supported by multiple lines of evidence. The aim of this study was to examine the modulation of corticomotor excitability during two types of strategies for motor imagery: Kinesthetic Motor Imagery (KMI) and Visual Motor Imagery (VMI) in a phasic thumb movement task. Transcranial magnetic stimulation (TMS) was applied over the contralateral motor cortex (M1) to elicit motor evoked potentials (MEPs) in the dominant abductor pollicis brevis (APB) and abductor digiti minimi (ADM). In a separate experiment, transcutaneous electrical stimuli were delivered to the median nerve at the dominant wrist, to elicit F-waves from APB. Imagined task performance was paced with a 1 Hz auditory metronome, and stimuli were delivered either 50 ms before (ON phase), or 450 ms after (OFF phase), the metronome beeps. Recordings were also made during two control conditions: Rest, and a Visual Static Imagery (VSI) condition. Significant MEP amplitude facilitation occurred only in APB, and only during the ON phase of KMI. F-wave persistence and amplitude were unaffected by imagery. These results demonstrate that kinesthetic, but not visual, motor imagery modulates corticomotor excitability, primarily at the supraspinal level. These findings have implications for the definition of motor imagery, and for its therapeutic applications.
运动想象和实际运动在中枢神经系统中涉及重叠神经结构这一假说得到了多方面证据的支持。本研究的目的是在一个阶段性拇指运动任务中，考察运动想象的两种策略：动觉运动想象（KMI）和视觉运动想象（VMI）过程中皮质运动兴奋性的调节情况。经颅磁刺激（TMS）作用于对侧运动皮层（M1），以引出优势侧拇短展肌（APB）和小指展肌（ADM）的运动诱发电位（MEP）。在另一个实验中，经皮电刺激施加于优势侧手腕的正中神经，以引出APB的F波。想象任务表现由1Hz的听觉节拍器控制，刺激在节拍器发出哔哔声之前50ms（开启阶段）或之后450ms（关闭阶段）施加。在两种对照条件下也进行了记录：静息状态和视觉静态想象（VSI）状态。显著的MEP波幅易化仅在APB中出现，且仅在KMI的开启阶段出现。F波的持续性和波幅不受想象的影响。这些结果表明，动觉而非视觉运动想象主要在脊髓上水平调节皮质运动兴奋性。这些发现对运动想象的定义及其治疗应用具有启示意义。
