Brovelli Andrea, Ding Mingzhou, Ledberg Anders, Chen Yonghong, Nakamura Richard, Bressler Steven L
Center for Complex Systems and Brain Sciences, Florida Atlantic University, Boca Raton, FL 33431, USA.
Proc Natl Acad Sci U S A. 2004 Jun 29;101(26):9849-54. doi: 10.1073/pnas.0308538101. Epub 2004 Jun 21.
Previous studies have shown that synchronized beta frequency (14-30 Hz) oscillations in the primary motor cortex are involved in maintaining steady contractions of contralateral arm and hand muscles. However, little is known about the role of postcentral cortical areas in motor maintenance and their patterns of interaction with motor cortex. We investigated the functional relations of beta-synchronized neuronal assemblies in pre- and postcentral areas of two monkeys as they pressed a hand lever during the wait period of a visual discrimination task. By using power and coherence spectral analysis, we identified a beta-synchronized large-scale network linking pre- and postcentral areas. We then used Granger causality spectra to measure directional influences among recording sites. In both monkeys, strong Granger causal influences were observed from primary somatosensory cortex to both motor cortex and inferior posterior parietal cortex, with the latter area also exerting Granger causal influences on motor cortex. Granger causal influences from motor cortex to postcentral sites, however, were weak in one monkey and not observed in the other. These results are the first, to our knowledge, to demonstrate in awake monkeys that synchronized beta oscillations bind multiple sensorimotor areas into a large-scale network during motor maintenance behavior and carry Granger causal influences from primary somatosensory and inferior posterior parietal cortices to motor cortex.
先前的研究表明，初级运动皮层中的同步β频率（14 - 30赫兹）振荡参与维持对侧手臂和手部肌肉的稳定收缩。然而，关于中央后回皮质区域在运动维持中的作用及其与运动皮层的相互作用模式，我们所知甚少。我们研究了两只猴子在视觉辨别任务的等待期按压手柄时，中央前回和中央后回区域中β同步神经元集群的功能关系。通过使用功率谱和相干谱分析，我们确定了一个连接中央前回和中央后回区域的β同步大规模网络。然后，我们使用格兰杰因果谱来测量记录位点之间的定向影响。在两只猴子中，均观察到从初级体感皮层到运动皮层和下顶叶后部皮层都有很强的格兰杰因果影响，而后一个区域对运动皮层也有格兰杰因果影响。然而，在一只猴子中，从运动皮层到中央后回位点的格兰杰因果影响较弱，而在另一只猴子中未观察到这种影响。据我们所知，这些结果首次在清醒猴子中证明，在运动维持行为期间，同步β振荡将多个感觉运动区域绑定成一个大规模网络，并携带从初级体感皮层和下顶叶后部皮层到运动皮层的格兰杰因果影响。
