McAvoy Mark, Larson-Prior Linda, Nolan Tracy S, Vaishnavi S Neil, Raichle Marcus E, d'Avossa Giovanni
Department of Radiology, Washington University School of Medicine, 4525 Scott Ave., Campus Box 8225, Rm. 2110, St. Louis, MO 63110, USA.
J Neurophysiol. 2008 Aug;100(2):922-31. doi: 10.1152/jn.90426.2008. Epub 2008 May 28.
The brain exhibits spontaneous neural activity that depends on the behavioral state of the organism. We asked whether the blood oxygenation level-dependent (BOLD) signal reflects these modulations. BOLD was measured under three steady-state conditions: while subjects kept their eyes closed, kept their eyes open, or while fixating. The BOLD spectral density was calculated across brain voxels and subjects. Visual, sensory-motor, auditory, and retrosplenial cortex showed modulations of the BOLD spectral density by resting state type. All modulated regions showed greater spontaneous BOLD oscillations in the eyes closed than the eyes open or fixation conditions, suggesting that the differences were endogenously driven. Next, we examined the pattern of correlations between regions whose ongoing BOLD signal was modulated by resting state type. Regional neuronal correlations were estimated using an analytic procedure from the comparison of BOLD-BOLD covariances in the fixation and eyes closed conditions. Most regions were highly correlated with one another, with the exception of the primary visual cortices, which showed low correlations with the other regions. In conclusion, changes in resting state were associated with synchronous modulations of spontaneous BOLD oscillations in cortical sensory areas driven by two spatially overlapping, but temporally uncorrelated signals.
大脑表现出依赖于机体行为状态的自发神经活动。我们询问血氧水平依赖(BOLD)信号是否反映了这些调节。在三种稳态条件下测量BOLD:受试者闭眼、睁眼或注视时。计算了跨脑体素和受试者的BOLD谱密度。视觉、感觉运动、听觉和压后皮质显示出BOLD谱密度受静息状态类型的调节。所有受调节区域在闭眼时比睁眼或注视条件下表现出更大的自发BOLD振荡,这表明这些差异是内源性驱动的。接下来,我们检查了其持续BOLD信号受静息状态类型调节的区域之间的相关性模式。使用一种分析程序,通过比较注视和闭眼条件下的BOLD-BOLD协方差来估计区域神经元相关性。除初级视觉皮质与其他区域相关性较低外,大多数区域彼此高度相关。总之,静息状态的变化与由两个空间重叠但时间不相关的信号驱动的皮质感觉区域自发BOLD振荡的同步调节有关。