Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
Cereb Cortex. 2010 Jun;20(6):1286-92. doi: 10.1093/cercor/bhp190. Epub 2009 Sep 25.
Low-frequency fluctuations (LFFs) are a major source of variation in fMRI data. This has been established in numerous experiments-particularly in the resting state. Here we investigate LFFs in a task-dependent setting. We hypothesized that LFFs may contain information about cognitive networks that are specific to the overall task domain without being time locked to stimulus onsets. We analyzed data of 6 fMRI experiments, 4 of which belonged to the language domain. After regressing out specifics of the experimental design and low-pass filtering (<0.1 Hz), we found that the 4 language experiments produced a correlational pattern that was not present in the 2 nonlanguage studies. Specifically, a region in the posterior part of the left superior temporal sulcus/gyrus was consistently correlated with both the left Brodmann's area 44 and the left frontal operculum in all 4 language studies, whereas this correlation was not found in the 2 other experiments. This finding indicates the existence of a basic network that acts as a general framework for language processing. In contrast to networks obtained by a conventional conjunction analysis of activation maps, this network is independent of experimental specifics such as stimulus onsets and exists in the low-frequency range.
低频波动（LFFs）是 fMRI 数据变化的主要来源。这在大量实验中得到了证实，尤其是在静息状态下。在这里，我们在依赖任务的环境中研究 LFFs。我们假设 LFFs 可能包含与整体任务领域相关的认知网络的信息，而无需与刺激开始时间锁定。我们分析了 6 项 fMRI 实验的数据，其中 4 项属于语言领域。在回归实验设计细节和低通滤波（<0.1 Hz）后，我们发现 4 项语言实验产生了一种在 2 项非语言研究中不存在的相关模式。具体来说，左颞上回/回后部的一个区域在所有 4 项语言研究中与左侧布罗德曼 44 区和左侧额骨外侧均呈一致相关，而在其他 2 项实验中则未发现这种相关性。这一发现表明存在一个基本的网络，作为语言处理的一般框架。与通过激活图的传统联合分析获得的网络相比，该网络独立于实验细节，如刺激开始时间，并存在于低频范围内。
