The Relationship between Brain Oscillations and BOLD Signal during Memory Formation: A Combined EEG-fMRI Study
The Relationship between Brain Oscillations and BOLD Signal during Memory Formation: A Combined EEG-fMRI Study
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DOI：
10.1523/jneurosci.3140-11.2011
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发表时间：
2011-11-02
影响因子：
5.3
通讯作者：
Baeuml, Karl-Heinz T.
中科院分区：
文献类型：
--
作者：
Hanslmayr, Simon;Volberg, Gregor;Baeuml, Karl-Heinz T.
先前的研究表明，θ波段的增加伴随着α / β波段的减少表明成功的记忆形成。然而，人们对这些编码相关的振荡记忆效应背后的大脑区域和认知过程知之甚少。我们在人类长期记忆编码过程中同时使用脑电图-功能磁共振成像记录来研究这种关系。与先前的研究一致，我们证明了β功率的降低和θ功率的增加对随后的回忆有积极的预测作用。在功能磁共振成像中，左侧前额叶下皮层和右侧海马旁回的较强活动与成功的记忆形成相关。脑电源定位发现，β波段的后续记忆效应定位于左侧下前额叶皮层，而θ波段的后续记忆效应定位于内侧颞叶区域。脑电图与BOLD活动的逐次相关性显示，β功率与左下前额叶皮层活动负相关。这种相关性在后来能够成功回忆起来的项目与后来被遗忘的项目之间更为明显。基于这些发现，我们认为左下前额叶皮层的β振荡表明语义编码过程，而内侧颞叶的θ振荡反映了一个项目与其时空背景的结合。
Previous studies demonstrated that increases in the theta frequency band with concomitant decreases in the alpha/beta frequency band indicate successful memory formation. However, little is known about the brain regions and the cognitive processes that underlie these encoding-related oscillatory memory effects. We investigated this relationship using simultaneous EEG-fMRI recordings in humans during long-term memory encoding. In line with prior studies, we demonstrate that a decrease in beta power and an increase in theta power positively predict subsequent recall. In fMRI, stronger activity in the left inferior prefrontal cortex and the right parahippocampal gyrus correlated with successful memory formation. EEG source localization revealed that the subsequent memory effect in the beta band was localized in the left inferior prefrontal cortex, whereas the effect in the theta band was localized in medial temporal lobe regions. Trial-by-trial correlations between EEG and BOLD activity showed that beta power correlated negatively with left inferior prefrontal cortex activity. This correlation was more pronounced for items that could later be successfully recalled compared to items later forgotten. Based on these findings, we suggest that beta oscillations in the left inferior prefrontal cortex indicate semantic encoding processes, whereas theta oscillations in the medial temporal lobe reflect the binding of an item to its spatiotemporal context.