The role of synchrony and oscillations in the motor output
The role of synchrony and oscillations in the motor output
复制标题
DOI：
10.1007/s002210050825
复制
发表时间：
1999-09-01
影响因子：
2
通讯作者：
Lemon, RN
中科院分区：
文献类型：
--
作者：
Baker, SN;Kilner, JM;Lemon, RN
目前，人们对神经放电的同步性及其在神经系统信息编码中可能发挥的潜在作用非常感兴趣。我们描述了一些最近的结果，从同步的运动系统内的调查。本研究记录了猴子进行精确握力训练时初级运动皮层的局部场电位（lfp）和已识别的锥体束神经元（ptn）。lfp在20 ~ 30 Hz范围内出现振荡活动，与对侧手和前臂肌肉的整流肌电图一致。这种振荡同步表现出高度的特定任务依赖性，只出现在动物保持稳定握力的部分任务中，而不是在之前或之后的运动阶段。ptn与LFP振荡相锁，这意味着皮层活动和肌电图之间至少部分的一致性是由皮质脊髓纤维介导的。PTN对LFP振荡的相位锁定在PTN对之间产生了任务依赖的振荡同步，通过单单元互相关直方图进行了评估。正常的人类受试者也进行了类似于猴子录音的精确抓握的录音。从手部和前臂固有肌肉记录的成对肌电图显示20-30赫兹的相干性，在任务执行过程中被调制，仅在稳定收缩期间出现。我们认为肌电-肌电同步的这些变化反映了皮质脊髓系统同步驱动水平的变化。根据局部皮层电路模型的结果，讨论了皮层振荡的产生。其他的建模工作表明，皮质脊髓输入的同步可以更有效地招募运动神经元，从肌肉中产生更多的输出力，而不是以相同的平均速率发射的异步输入。对同步振荡在电机系统中的作用提出了一个推测性的假设，这与迄今为止的实验观察结果是一致的。
There is currently much interest in the synchronisation of neural discharge and the potential role it may play in information coding within the nervous system. We describe some recent results from investigations of synchronisation within the motor system. Local field potentials (LFPs) and identified pyramidal tract neurones (PTNs) were recorded from the primary motor cortex of monkeys trained to perform a precision grip task. The LFPs showed bursts of oscillatory activity at 20-30 Hz, which were coherent with the rectified electromyographs (EMG) of contralateral hand and forearm muscles. This oscillatory synchronisation showed a high ly specific task dependence, being present only during the part of the task when the animal maintained a steady grip and not during the movement phases before or after it. PTNs were phase-locked to LFP oscillations, implying that at least part of the coherence between cortical activity and EMG was mediated by corticospinal fibres. The phase locking of the PTNs to LFP oscillations produced task-dependent oscillatory synchronisation between PTN pairs, as assessed by the single-unit crosscorrelation histogram. Recordings were also made from normal human subjects performing a precision grip similar to that used in the monkey recordings. Pairs of EMGs recorded from intrinsic hand and forearm muscles showed 20-30 Hz coherence, which modulated during task performance, being present only during periods of steady contraction. We suggest that these changes in EMG-EMG synchronisation reflect changing levels of synchronous drive from the corticospinal system. The generation of oscillations in the cortex is discussed in the light of results from a model of local cortical circuits. Other modelling work has shown that synchrony in the corticospinal inputs could act to recruit motoneurones more efficiently, producing more output force from a muscle than asynchronous inputs firing at the same mean rate. A speculative hypothesis is presented on the role of synchronous oscillations in the motor system, which is consistent with experimental observations to date.