Kilner J M, Baker S N, Salenius S, Hari R, Lemon R N
Sobell Department of Neurophysiology, Institute of Neurology, Queen Square, London WC1N 3BG, United Kingdom.
J Neurosci. 2000 Dec 1;20(23):8838-45. doi: 10.1523/JNEUROSCI.20-23-08838.2000.
Cortical oscillations have been the target of many recent investigations, because it has been proposed that they could function to solve the "binding" problem. In the motor cortex, oscillatory activity has been reported at a variety of frequencies between approximately 4 and approximately 60 Hz. Previous research has shown that 15-30 Hz oscillatory activity in the primary motor cortex is coherent or phase locked to activity in contralateral hand and forearm muscles during isometric contractions. However, the function of this oscillatory activity remains unclear. Is it simply an epiphenomenon or is it related to specific motor parameters? In this study, we investigated task-dependent modulation in coherence between motor cortex and hand muscles during precision grip tasks. Twelve right-handed subjects used index finger and thumb to grip two levers that were under robotic control. Each lever was fitted with a sensitive force gauge. Subjects received visual feedback of lever force levels and were instructed to keep them within target boxes throughout each trial. Surface EMGs were recorded from four hand and forearm muscles, and magnetoencephalography (MEG) was recorded using a 306 channel neuromagnetometer. All subjects showed significant levels of coherence (0.086-0.599) between MEG and muscle in the 15-30 Hz range. Coherence was significantly smaller when the task was performed under an isometric condition (levers fixed) compared with a compliant condition in which subjects moved the levers against a spring-like load. Furthermore, there was a positive, significant relationship between the level of coherence and the degree of lever compliance. These results argue in favor of coherence between cortex and muscle being related to specific parameters of hand motor function.
皮层振荡已成为近期许多研究的目标，因为有人提出它们可能起到解决“绑定”问题的作用。在运动皮层中，已报道在大约4赫兹至大约60赫兹的各种频率下存在振荡活动。先前的研究表明，在等长收缩期间，初级运动皮层中15 - 30赫兹的振荡活动与对侧手部和前臂肌肉的活动是相干的或锁相的。然而，这种振荡活动的功能仍不清楚。它仅仅是一种附带现象，还是与特定的运动参数有关？在本研究中，我们调查了在精确抓握任务期间运动皮层与手部肌肉之间相干性的任务依赖性调制。12名右利手受试者用食指和拇指抓握两个由机器人控制的杠杆。每个杠杆都装有一个灵敏的测力计。受试者会收到杠杆力水平的视觉反馈，并被指示在每个试验过程中保持在目标框内。从四块手部和前臂肌肉记录表面肌电图，并用306通道神经磁强计记录脑磁图（MEG）。所有受试者在15 - 30赫兹范围内的MEG与肌肉之间均表现出显著水平的相干性（0.086 - 0.599）。与受试者在类似弹簧负载下移动杠杆的顺应性条件相比，在等长条件（杠杆固定）下执行任务时，相干性显著更小。此外，相干性水平与杠杆顺应程度之间存在正的显著关系。这些结果支持皮层与肌肉之间的相干性与手部运动功能的特定参数有关的观点。
