Mat Safri Norlaili, Murayama Nobuki, Hayashida Yuki, Igasaki Tomohiko
Department of Graduate School of Science and Technology, Kumamoto University, Kurokami 2-39-1, Kumamoto, Japan.
Brain Res. 2007 Jun 25;1155:81-92. doi: 10.1016/j.brainres.2007.04.052. Epub 2007 Apr 25.
To study the effects of external visual stimulation on motor cortex-muscle synchronization, coherence between electroencephalography (EEG) and electromyography (EMG) was measured in normal subjects under Before, Task (visual task: Ignore or Count, or arithmetic task) and After conditions. The control (Before and After) conditions required the subject to maintain first dorsal interosseous muscle contraction without visual stimulation. In the visual task, a random series of visual stimuli were displayed on a screen while the subjects maintained the muscle contraction. The subjects were asked to ignore the stimuli in the Ignore condition and to count certain stimuli in the Count condition. Also, in the arithmetic task, the subjects were asked to perform a simple subtraction. The EEG-EMG coherence found at C(3) site at 13-30 Hz (beta) was increased and sustained in magnitude during the Ignore and Count conditions, respectively. To examine the cause of the change of coherence, changes of EEG and EMG spectral power were computed for each frequency band. There was little change in the EMG spectral power in any frequency bands. While the spectral power of EEG unchanged in the beta band, it significantly increased and decreased in the range of 8-12 Hz and of 31-50 Hz, respectively, for both Ignore and Count conditions, not only at the C(3) site but at various sites as well. These results were in contrast to those obtained for the arithmetic task: the beta band EEG-EMG coherence was attenuated and the EEG spectral power at 4-7 Hz and at 31-50 Hz were significantly increased and decreased, respectively. As a conclusion, the present results are consistent with the idea that the enhanced 8-12 Hz/decreased 31-50 Hz oscillations affect strength of the beta band cortico-muscular synchronization by suppressing the visual processing.
为研究外部视觉刺激对运动皮层 - 肌肉同步性的影响，在正常受试者处于刺激前、任务（视觉任务：忽略或计数，或算术任务）和刺激后条件下，测量脑电图（EEG）与肌电图（EMG）之间的相干性。对照（刺激前和刺激后）条件要求受试者在无视觉刺激的情况下保持第一背侧骨间肌收缩。在视觉任务中，当受试者保持肌肉收缩时，一系列随机的视觉刺激会显示在屏幕上。在忽略条件下，要求受试者忽略刺激；在计数条件下，要求受试者对某些刺激进行计数。此外，在算术任务中，要求受试者进行简单减法运算。在忽略和计数条件下，分别在C(3)位点13 - 30 Hz（β频段）处发现的EEG - EMG相干性在幅度上增加并持续。为检查相干性变化的原因，计算了每个频段的EEG和EMG频谱功率变化。在任何频段，EMG频谱功率几乎没有变化。虽然EEG的频谱功率在β频段不变，但在忽略和计数条件下，不仅在C(3)位点，在各个位点8 - 12 Hz范围内频谱功率均显著增加，31 - 50 Hz范围内频谱功率均显著降低。这些结果与算术任务所获得的结果相反：β频段的EEG - EMG相干性减弱，4 - 7 Hz和31 - 50 Hz处的EEG频谱功率分别显著增加和降低。总之，目前的结果与以下观点一致，即增强的8 - 12 Hz/降低的31 - 50 Hz振荡通过抑制视觉处理来影响β频段皮质 - 肌肉同步性的强度。
