Morcom Alexa M, Fletcher Paul C
Brain Mapping Unit, Department of Psychiatry, University of Cambridge, UK.
Neuroimage. 2007 Oct 1;37(4):1073-82. doi: 10.1016/j.neuroimage.2007.06.019. Epub 2007 Jul 3.
In the last few years, the notion that the brain has a default or intrinsic mode of functioning has received increasing attention. The idea derives from observations that a consistent network of brain regions shows high levels of activity when no explicit task is performed and participants are asked simply to rest. The importance of this putative "default mode" is asserted on the basis of the substantial energy demand associated with such a resting state and of the suggestion that rest entails a finely tuned balance between metabolic demand and regionally regulated blood supply. These observations, together with the fact that the default network is more active at rest than it is in a range of explicit tasks, have led some to suggest that it reflects an absolute baseline, one that must be understood and used if we are to develop a comprehensive picture of brain functioning. Here, we examine the assumptions that are generally made in accepting the importance of the "default mode". We question the value, and indeed the interpretability, of the study of the resting state and suggest that observations made under resting conditions have no privileged status as a fundamental metric of brain functioning. In doing so, we challenge the utility of studies of the resting state in a number of important domains of research.
在过去几年里，大脑具有默认或固有功能模式这一观念受到了越来越多的关注。这一观点源于这样的观察：当不执行明确任务且参与者仅被要求休息时，一个由大脑区域组成的连贯网络会表现出高水平的活动。基于与这种静息状态相关的大量能量需求，以及静息意味着代谢需求与局部调节的血液供应之间存在精细平衡这一观点，人们断言了这种假定的“默认模式”的重要性。这些观察结果，再加上默认网络在静息时比在一系列明确任务中更活跃这一事实，使得一些人认为它反映了一个绝对基线，如果我们要全面了解大脑功能，就必须理解并利用这个基线。在此，我们审视了在接受“默认模式”重要性时通常所做的假设。我们质疑静息状态研究的价值，乃至其可解释性，并表明在静息条件下所做的观察作为大脑功能的基本指标并无特殊地位。在此过程中，我们对静息状态研究在一些重要研究领域的实用性提出了质疑。
