Max-Planck Institute for Biological Cybernetics, Tübingen, Germany.
Neuroimage. 2011 May 15;56(2):837-42. doi: 10.1016/j.neuroimage.2010.04.265. Epub 2010 May 6.
Gamma oscillations of the electromagnetic field of the brain are known to be involved in a variety of cognitive processes, and are believed to be fundamental for information processing within the brain. While gamma oscillations have been shown to be correlated with brain rhythms at different frequencies, to date no empirical evidence has been presented that supports a causal influence of gamma oscillations on other brain rhythms. In this work, we study the relation of gamma oscillations and the sensorimotor rhythm (SMR) in healthy human subjects using electroencephalography. We first demonstrate that modulation of the SMR, induced by motor imagery of either the left or right hand, is positively correlated with the power of frontal and occipital gamma oscillations, and negatively correlated with the power of centro-parietal gamma oscillations. We then demonstrate that the most simple causal structure, capable of explaining the observed correlation of gamma oscillations and the SMR, entails a causal influence of gamma oscillations on the SMR. This finding supports the fundamental role attributed to gamma oscillations for information processing within the brain, and is of particular importance for brain-computer interfaces (BCIs). As modulation of the SMR is typically used in BCIs to infer a subject's intention, our findings entail that gamma oscillations have a causal influence on a subject's capability to utilize a BCI for means of communication.
脑电磁场的伽马振荡已知参与各种认知过程，被认为是大脑内信息处理的基础。虽然已经证明伽马振荡与不同频率的脑节律相关，但迄今为止没有实证证据表明伽马振荡对其他脑节律有因果影响。在这项工作中，我们使用脑电图研究了健康人类受试者中的伽马振荡与感觉运动节律（SMR）之间的关系。我们首先证明，通过左手或右手的运动想象诱导的 SMR 调制与额部和枕部伽马振荡的功率呈正相关，与中央顶叶伽马振荡的功率呈负相关。然后我们证明，最基本的因果结构，能够解释观察到的伽马振荡和 SMR 的相关性，需要伽马振荡对 SMR 的因果影响。这一发现支持了归因于伽马振荡在大脑内信息处理中的基本作用，对于脑机接口（BCI）尤其重要。由于 SMR 的调制通常用于 BCI 来推断受试者的意图，我们的发现意味着伽马振荡对受试者利用 BCI 进行通信的能力有因果影响。
