Fukunaga Masaki, Horovitz Silvina G, van Gelderen Peter, de Zwart Jacco A, Jansma J Martijn, Ikonomidou Vasiliki N, Chu Renxin, Deckers Roel H R, Leopold David A, Duyn Jeff H
Advanced MRI, LFMI, NINDS, National Institutes of Health, Bethesda, MD 20892-1065, USA.
Magn Reson Imaging. 2006 Oct;24(8):979-92. doi: 10.1016/j.mri.2006.04.018. Epub 2006 Jun 8.
A number of recent studies of human brain activity using blood-oxygen-level-dependent (BOLD) fMRI and EEG have reported the presence of spatiotemporal patterns of correlated activity in the absence of external stimuli. Although these patterns have been hypothesized to contain important information about brain architecture, little is known about their origin or about their relationship to active cognitive processes such as conscious awareness and monitoring of the environment. In this study, we have investigated the amplitude and spatiotemporal characteristics of resting-state activity patterns and their dependence on the subjects' alertness. For this purpose, BOLD fMRI was performed at 3.0 T on 12 normal subjects using a visual stimulation protocol, followed by a 27 min rest period, during which subjects were allowed to fall asleep. In subjects who were asleep at the end of the scan, we found (a) a higher amplitude of BOLD signal fluctuation during rest compared with subjects who were awake at the end of the scan; (b) spatially independent patterns of correlated activity that involve all of gray matter, including deep brain nuclei; (c) many patterns that were consistent across subjects; (d) that average percentage levels of fluctuation in visual cortex (VC) and whole brain were higher in subjects who were asleep (up to 1.71% and 1.16%, respectively) than in those who were awake (up to 1.15% and 0.96%) at the end of the scan and were comparable with those levels evoked by intense visual stimulation (up to 1.85% and 0.76% for two subject groups); (e) no confirmation of correlation, positive or negative, between thalamus and VC found in earlier studies. These findings suggest that resting-state activity continues during sleep and does not require active cognitive processes or conscious awareness.
最近一些使用血氧水平依赖性功能磁共振成像（BOLD fMRI）和脑电图对人类大脑活动进行的研究报告称，在没有外部刺激的情况下存在相关活动的时空模式。尽管这些模式被假设包含有关大脑结构的重要信息，但对于它们的起源以及它们与诸如意识觉知和环境监测等主动认知过程的关系却知之甚少。在本研究中，我们调查了静息状态活动模式的幅度及时空特征，以及它们对受试者警觉性的依赖性。为此，在3.0T磁场下，对12名正常受试者采用视觉刺激方案进行BOLD fMRI检查，随后是27分钟的休息期，在此期间允许受试者入睡。在扫描结束时入睡的受试者中，我们发现：（a）与扫描结束时清醒的受试者相比，休息期间BOLD信号波动幅度更高；（b）相关活动的空间独立模式涉及所有灰质，包括深部脑核；（c）许多模式在受试者之间是一致的；（d）在扫描结束时入睡的受试者中，视觉皮层（VC）和全脑的平均波动百分比水平（分别高达1.71%和1.16%）高于清醒的受试者（分别高达1.15%和0.96%），并且与强烈视觉刺激诱发的水平相当（两个受试者组分别高达1.85%和0.76%）；（e）未证实早期研究中发现的丘脑与VC之间存在正相关或负相关。这些发现表明，静息状态活动在睡眠期间持续存在，并且不需要主动认知过程或意识觉知。
