Brain Research Unit, Low Temperature Laboratory, Aalto University, Finland.
Neuroimage. 2012 Mar;60(1):29-36. doi: 10.1016/j.neuroimage.2011.11.087. Epub 2011 Dec 7.
Phase-locked evoked responses and event-related modulations of spontaneous rhythmic activity are the two main approaches used to quantify stimulus- or task-related changes in electrophysiological measures. The relationship between the two has been widely theorized upon but empirical research has been limited to the primary visual and sensorimotor cortex. However, both evoked responses and rhythms have been used as markers of neural activity in paradigms ranging from simple sensory to complex cognitive tasks. While some spatial agreement between the two phenomena has been observed, typically only one of the measures has been used in any given study, thus disallowing a direct evaluation of their exact spatiotemporal relationship. In this study, we sought to systematically clarify the connection between evoked responses and rhythmic activity. Using both measures, we identified the spatiotemporal patterns of task effects in three magnetoencephalography (MEG) data sets, all variants of a picture naming task. Evoked responses and rhythmic modulation yielded largely separate networks, with spatial overlap mainly in the sensorimotor and primary visual areas. Moreover, in the cortical regions that were identified with both measures the experimental effects they conveyed differed in terms of timing and function. Our results suggest that the two phenomena are largely detached and that both measures are needed for an accurate portrayal of brain activity.
锁相诱发响应和事件相关调制的自发节律活动是用于量化电生理测量中刺激或任务相关变化的两种主要方法。这两种方法之间的关系已经被广泛理论化，但实证研究仅限于主要的视觉和感觉运动皮层。然而，诱发响应和节律都被用作从简单感觉到复杂认知任务等范式中神经活动的标记物。虽然已经观察到这两种现象之间存在一些空间一致性，但通常在任何给定的研究中只使用其中一种测量方法，因此无法直接评估它们的确切时空关系。在这项研究中，我们试图系统地阐明诱发响应和节律活动之间的联系。使用这两种方法，我们在三个脑磁图（MEG）数据集（都是图片命名任务的变体）中确定了任务效应的时空模式。诱发响应和节律调制产生了很大程度上分离的网络，空间重叠主要在感觉运动和初级视觉区域。此外，在被这两种方法都识别出来的皮质区域中，它们所传递的实验效应在时间和功能上有所不同。我们的结果表明，这两种现象在很大程度上是分离的，两种方法都需要准确描述大脑活动。
