Neurophysiology of the BOLD fMRI signal in awake monkeys
Neurophysiology of the BOLD fMRI signal in awake monkeys
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DOI：
10.1016/j.cub.2008.03.054
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发表时间：
2008-05-06
期刊：
影响因子：
9.2
通讯作者：
Logothetis, Nikos K.
中科院分区：
文献类型：
--
作者：
Goense, Jozien B. M.;Logothetis, Nikos K.
背景资料：在麻醉猴的初级视皮层同时记录神经活动和血氧水平依赖（BOLD）的功能磁共振成像（fMRI）显示不同程度的相关性之间的fMRI信号和不同类型的神经活动，如局部场电位（LFPs），多单位活动（MUA），和单单位活动（SUA）。上述研究提出的一个重要问题是，报告的相关性是否也适用于警觉的受试者。结果如下：训练猴子执行固定任务，同时使用每个记录部位的感受野内的刺激来引起神经反应，然后是BOLD反应。我们表明-也在警觉行为的猴子-虽然LFP和MUA作出重大贡献的BOLD响应，LFP是更好，更可靠的预测BOLD信号。此外，当MUA反应适应但LFP保持不受影响时，BOLD信号保持不变。结论：当LFP和MUA具有不同的时间演变时，BOLD信号与场电位的持续耦合表明BOLD主要由给定皮层区域中的输入的局部处理来确定。在警觉动物中，BOLD信号方差的最大部分由最可能与神经调节相关的LFP范围（20-60 Hz）解释。最后，清醒和麻醉受试者的结果相似，表明至少在V1中麻醉不是混杂因素。这使得人类功能磁共振成像结果与在警觉或麻醉动物中获得的大量电生理结果进行比较成为可能。
Background: Simultaneous intracortical recordings of neural activity and blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) in primary visual cortex of anesthetized monkeys demonstrated varying degrees of correlation between fMRI signals and the different types of neural activity, such as local field potentials (LFPs), multiple-unit activity (MUA), and single-unit activity (SUA). One important question raised by the aforementioned investigation is whether the reported correlations also apply to alert subjects. Results: Monkeys were trained to perform a fixation task while stimuli within the receptive field of each recording site were used to elicit neural responses followed by a BOLD response. We show - also in alert behaving monkeys - that although both LFP and MUA make significant contributions to the BOLD response, LFPs are better and more reliable predictors of the BOLD signal. Moreover, when MUA responses adapt but LFP remains unaffected, the BOLD signal remains unaltered. Conclusions: The persistent coupling of the BOLD signal to the field potential when LFP and MUA have different time evolutions suggests that BOLD is primarily determined by the local processing of inputs in a given cortical area. In the alert animal the largest portion of the BOLD signal's variance is explained by an LFP range (20-60 Hz) that is most likely related to neuromodulation. Finally, the similarity of the results in alert and anesthetized subjects indicates that at least in V1 anesthesia is not a confounding factor. This enables the comparison of human fMRI results with a plethora of electrophysiological results obtained in alert or anesthetized animals.