de Munck J C, Gonçalves S I, Huijboom L, Kuijer J P A, Pouwels P J W, Heethaar R M, Lopes da Silva F H
Department PMT, VU Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands.
Neuroimage. 2007 Apr 15;35(3):1142-51. doi: 10.1016/j.neuroimage.2007.01.022. Epub 2007 Feb 4.
EEG was recorded during fMRI scanning of 16 normal controls in resting condition with eyes closed. Time variations of the occipital alpha band amplitudes were correlated to the fMRI signal variations to obtain insight into the hemodynamic correlates of the EEG alpha activity. Contrary to earlier studies, no a priori assumptions were made on the expected shape of the alpha band response function (ARF). The ARF of different brain regions and subjects were explored and compared. It was found that: (1) the ARF of the thalamus is mainly positive. (2) The ARFs at the occipital and left and right parietal points are similar in amplitude and timing. (3) The peak time of the thalamus is a few seconds earlier than that of occipital and parietal cortex. (4) No systematic BOLD activity was found preceding the alpha band activity, although in the two subjects with the strongest alpha band power such correlation was present. (5) There is a strong and immediate positive correlation at the eyeball, and a strong negative correlation at the back of the eye. Furthermore, it was found that in one subject the cortical ARF was positive, contrary to the other subjects. Finally, a cluster analysis of the observed ARF, in combination with a Modulated Sine Model (MSM) fit to the estimated ARF, revealed that within the cortex the ARF peak time shows a spatial pattern that may be interpreted as a traveling wave. The spatial pattern of alpha band response function represents the combined effect of local differences in electrical alpha band activity and local differences in the hemodynamic response function (HRF) onto these electrical activities. To disentangle the contributions of both factors, more advanced integration of EEG inverse modeling and hemodynamic response modeling is required in future studies.
在16名正常对照者闭眼静息状态下进行功能磁共振成像（fMRI）扫描时记录脑电图（EEG）。枕叶α波频段振幅的时间变化与fMRI信号变化相关，以深入了解EEGα活动的血液动力学相关性。与早期研究相反，未对α波频段响应函数（ARF）的预期形状做出先验假设。对不同脑区和受试者的ARF进行了探索和比较。结果发现：（1）丘脑的ARF主要为正。（2）枕叶以及左右顶叶点的ARF在振幅和时间上相似。（3）丘脑的峰值时间比枕叶和顶叶皮质早几秒。（4）尽管在α波频段功率最强的两名受试者中存在这种相关性，但在α波频段活动之前未发现系统性的血氧水平依赖（BOLD）活动。（5）眼球处存在强且即时的正相关，眼后存在强负相关。此外，发现一名受试者的皮质ARF为正，这与其他受试者不同。最后，对观察到的ARF进行聚类分析，并结合对估计的ARF进行调制正弦模型（MSM）拟合，结果显示在皮质内ARF峰值时间呈现出一种可解释为行波的空间模式。α波频段响应函数的空间模式代表了α波频段电活动的局部差异以及血液动力学响应函数（HRF）对这些电活动的局部差异的综合影响。为了区分这两个因素的贡献，未来研究需要更先进的EEG逆模型和血液动力学响应模型的整合。
