Fransson Peter
MR Research Center, Cognitive Neurophysiology, Department of Clinical Neuroscience, Karolinska Institute/Karolinska University Hospital, Stockholm, Sweden.
Hum Brain Mapp. 2005 Sep;26(1):15-29. doi: 10.1002/hbm.20113.
Recent neuroimaging studies have lead to the proposal that rest is characterized by an organized, baseline level of activity, a default mode of brain function that is suspended during specific goal-oriented mental activity. Previous studies have shown that the primary function subserved by the default mode is that of an introspectively oriented, self-referential mode of mental activity. The default mode of brain function hypothesis is readdressed from the perspective of the presence of low-frequency blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) signal changes (0.012-0.1 Hz) in the resting brain. The results show that the brain during rest is not tonically active in a single mode of brain function. Rather, the findings presented here suggest that the brain recurrently toggles between an introspectively oriented mode (default mode) and a state-of-mind that tentatively might be interpreted as an extrospectively oriented mode that involves a readiness and alertness to changes in the external and internal environment.
最近的神经影像学研究提出,静息状态的特征是一种有组织的基线活动水平,即一种在特定目标导向性思维活动期间暂停的大脑功能默认模式。先前的研究表明,默认模式所支持的主要功能是一种内省导向、自我参照的思维活动模式。从静息大脑中低频血氧水平依赖(BOLD)功能磁共振成像(fMRI)信号变化(0.012 - 0.1 Hz)的角度重新审视大脑功能默认模式假说。结果表明,静息时大脑并非以单一的大脑功能模式持续活跃。相反,此处呈现的研究结果表明,大脑在一种内省导向模式(默认模式)和一种心态状态之间反复切换,这种心态状态可能暂时被解释为一种外向导向模式,涉及对外部和内部环境变化的准备和警觉。