Brain-wide ongoing activity is responsible for significant cross-trial BOLD variability.
Brain-wide ongoing activity is responsible for significant cross-trial BOLD variability.
复制标题
全脑持续活动是造成显着的跨试验 BOLD 变异的原因。
DOI：
10.1093/cercor/bhac016
复制
发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Zhang,Nanyin
中科院分区：
文献类型：
--
作者：
Zhang,Qingqing;Cramer,SamuelR;Ma,Zilu;Turner,KevinL;Gheres,KyleW;Liu,Yikang;Drew,PatrickJ;Zhang,Nanyin
基于任务的功能性磁共振成像（fMRI）的一个臭名昭著的问题是它的大的跨试验变异性。为了定量地表征这种可变性，可以将血氧水平依赖（BOLD）信号建模为刺激相关和正在进行的（即刺激无关）分量的线性总和。然而，系统的调查，正在进行的BOLD组件的时空特征，以及这些功能如何影响的BOLD响应仍然缺乏。在这里，我们测量了清醒大鼠对光开始和光偏移的fMRI反应。同时用钙基纤维光度计记录神经元的反应。我们确定，区域间BOLD信号在零时滞时在全脑范围内高度相关，包括对视觉刺激没有反应的区域，这表明正在进行的活动在整个大脑中共同波动。去除这种正在进行的活动将BOLD反应的交叉试验变异性降低了约30%，并增加了其与Ca2+信号的一致性。此外，负的持续BOLD活动有时主导了刺激驱动的反应，并导致刺激后BOLD下冲。这些结果表明，全脑正在进行的活动是负责显着的跨试验BOLD变异，这部分可以可靠地量化和删除，以提高fMRI响应的可靠性。重要的是，这种方法可以推广到几乎所有的功能磁共振成像实验，而不改变刺激范例。
A notorious issue of task-based functional magnetic resonance imaging (fMRI) is its large cross-trial variability. To quantitatively characterize this variability, the blood oxygenation level-dependent (BOLD) signal can be modeled as a linear summation of a stimulation-relevant and an ongoing (i.e. stimulation-irrelevant) component. However, systematic investigation on the spatiotemporal features of the ongoing BOLD component and how these features affect the BOLD response is still lacking. Here we measured fMRI responses to light onsets and light offsets in awake rats. The neuronal response was simultaneously recorded with calcium-based fiber photometry. We established that between-region BOLD signals were highly correlated brain-wide at zero time lag, including regions that did not respond to visual stimulation, suggesting that the ongoing activity co-fluctuates across the brain. Removing this ongoing activity reduced cross-trial variability of the BOLD response by ~30% and increased its coherence with the Ca2+signal. Additionally, the negative ongoing BOLD activity sometimes dominated over the stimulation-driven response and contributed to the post-stimulation BOLD undershoot. These results suggest that brain-wide ongoing activity is responsible for significant cross-trial BOLD variability, and this component can be reliably quantified and removed to improve the reliability of fMRI response. Importantly, this method can be generalized to virtually all fMRI experiments without changing stimulation paradigms.