The Mind Research Network, Albuquerque, New Mexico 87131, USA.
Neuroimage. 2010 Oct 1;52(4):1252-60. doi: 10.1016/j.neuroimage.2010.05.053. Epub 2010 May 25.
Concurrent EEG-fMRI studies have provided increasing details of the dynamics of intrinsic brain activity during the resting state. Here, we investigate a prominent effect in EEG during relaxed resting, i.e. the increase of the alpha power when the eyes are closed compared to when the eyes are open. This phenomenon is related to changes in thalamo-cortical and cortico-cortical synchronization. In order to investigate possible changes to EEG-fMRI coupling and fMRI functional connectivity during the two states we adopted a data-driven approach that fuses the multimodal data on the basis of parallel ICA decompositions of the fMRI data in the spatial domain and of the EEG data in the spectral domain. The power variation of a posterior alpha component was used as a reference function to deconvolve the hemodynamic responses from occipital, frontal, temporal, and subcortical fMRI components. Additionally, we computed the functional connectivity between these components. The results showed widespread alpha hemodynamic responses and high functional connectivity during eyes-closed (EC) rest, while eyes open (EO) resting abolished many of the hemodynamic responses and markedly decreased functional connectivity. These data suggest that generation of local hemodynamic responses is highly sensitive to state changes that do not involve changes of mental effort or awareness. They also indicate the localized power differences in posterior alpha between EO and EC in resting state data are accompanied by spatially widespread amplitude changes in hemodynamic responses and inter-regional functional connectivity, i.e. low frequency hemodynamic signals display an equivalent of alpha reactivity.
同时进行的 EEG-fMRI 研究为静息状态下内在大脑活动的动力学提供了越来越多的细节。在这里，我们研究了 EEG 在放松休息时的一个突出效应，即与睁眼相比，闭眼时的 alpha 功率增加。这种现象与丘脑-皮质和皮质-皮质同步的变化有关。为了研究两种状态下 EEG-fMRI 耦合和 fMRI 功能连接可能发生的变化，我们采用了一种数据驱动的方法，该方法基于 fMRI 数据在空间域和 EEG 数据在光谱域的并行 ICA 分解，融合多模态数据。后 alpha 分量的功率变化被用作参考函数，从枕部、额部、颞部和皮质下 fMRI 分量中解卷积血流动力学反应。此外，我们计算了这些分量之间的功能连接。结果表明，在闭眼（EC）休息时，广泛存在 alpha 血流动力学反应和高功能连接，而睁眼（EO）休息时，许多血流动力学反应被消除，功能连接明显减少。这些数据表明，局部血流动力学反应的产生对不涉及精神努力或意识变化的状态变化非常敏感。它们还表明，静息状态数据中 EO 和 EC 之间后 alpha 局部功率差异伴随着血流动力学反应和区域间功能连接的广泛空间变化，即低频血流动力学信号显示出与 alpha 反应性等效的信号。
