Self-similar correlation function in brain resting-state functional magnetic resonance imaging
Self-similar correlation function in brain resting-state functional magnetic resonance imaging
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DOI：
10.1098/rsif.2010.0416
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发表时间：
2011-04-01
影响因子：
3.9
通讯作者：
Turkheimer, Federico
中科院分区：
文献类型：
--
作者：
Expert, Paul;Lambiotte, Renaud;Turkheimer, Federico
适应性行为、认知和情感是大脑时空活动模式多样性的结果。神经科学中的一个重要问题是了解人类大脑的1000亿个神经元和100万亿个突触如何以灵活的方式产生如此庞大的皮层配置。此外，人们认识到，这种配置之间的时间相关性不能是任意的，但它们需要满足两个相互冲突的要求：虽然不同的皮层区域应该保持功能上相互隔离，但它们仍然必须作为一个集体，即它们在功能上是一体化的。在这里，我们调查这些大规模的动力学特性，通过检查的字符的时空相关性的大脑静息态活动。在物理系统中，通过测量在两个不同时间在空间中的两个不同点处记录的信号之间的相关系数来捕获空间和时间中的这些相关性。我们表明，这两点相关函数提取的静息态功能磁共振成像数据表现出自相似性的空间和时间。在空间上，通过考虑三个连续的空间粗粒化步骤来揭示自相似性，而在时间上，通过功率谱的1/f频率行为来揭示自相似性。未被发现的动力学自相似性意味着大脑自发地处于两个极端之间的连续变化（在空间和时间上）的中间状态，一个是过度的皮层整合，另一个是完全分离。这种动态特性可以被视为健康和疾病中大脑健康的重要标志。
Adaptive behaviour, cognition and emotion are the result of a bewildering variety of brain spatio-temporal activity patterns. An important problem in neuroscience is to understand the mechanism by which the human brain's 100 billion neurons and 100 trillion synapses manage to produce this large repertoire of cortical configurations in a flexible manner. In addition, it is recognized that temporal correlations across such configurations cannot be arbitrary, but they need to meet two conflicting demands: while diverse cortical areas should remain functionally segregated from each other, they must still perform as a collective, i.e. they are functionally integrated. Here, we investigate these large-scale dynamical properties by inspecting the character of the spatio-temporal correlations of brain resting-state activity. In physical systems, these correlations in space and time are captured by measuring the correlation coefficient between a signal recorded at two different points in space at two different times. We show that this two-point correlation function extracted from resting-state functional magnetic resonance imaging data exhibits self-similarity in space and time. In space, self-similarity is revealed by considering three successive spatial coarse-graining steps while in time it is revealed by the 1/f frequency behaviour of the power spectrum. The uncovered dynamical self-similarity implies that the brain is spontaneously at a continuously changing (in space and time) intermediate state between two extremes, one of excessive cortical integration and the other of complete segregation. This dynamical property may be seen as an important marker of brain well-being in both health and disease.