Forward and backward connections in the brain: A DCM study of functional asymmetries
Forward and backward connections in the brain: A DCM study of functional asymmetries
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DOI：
10.1016/j.neuroimage.2008.12.041
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发表时间：
2009-04-01
期刊：
影响因子：
5.7
通讯作者：
Friston, K. J.
中科院分区：
文献类型：
--
作者：
Chen, C. C.;Henson, R. N.;Friston, K. J.
在本文中，我们提供的证据功能不对称的向前和向后的连接，DE。大脑中的一种层次结构。我们利用一个神经元系统对另一个神经元系统的调节或非线性影响（即，有效连接性）需要不同频率之间的耦合。功能不对称的前向和后向连接，通过比较动态因果模型的脑磁图反应引起的视觉处理的正常和混乱的面孔。我们比较了模型与非线性（频率间）耦合在向前和向后的连接。贝叶斯模型比较表明，最好的模型具有非线性的前向和后向连接。使用最好的模型，然后我们量化特定频率的因果关系的影响，介导观察到的光谱响应。我们发现前向和后向连接之间存在显著的不对称性，即高皮质区的高（伽马）频率抑制了低皮质区的低（阿尔法）频率。这种抑制明显大于正向连接中的同源偶联。此外，当我们检查面选择性耦合（即，面下耦合减去乱序面）。这些结果突出了大脑区域之间非线性耦合的重要性，并指出人类大脑中向前和向后连接之间的功能不对称性，这与动物研究的解剖学和生理学证据一致。这种不对称性也与基于分层生成模型的大脑感知推理理论所暗示的功能结构一致。(c)2008年爱思唯尔公司All rights reserved.
In this paper, we provide evidence for functional asymmetries in forward and backward connections that de. ne hierarchical architectures in the brain. We exploit the fact that modulatory or nonlinear influences of one neuronal system on another (i.e., effective connectivity) entail coupling between different frequencies. Functional asymmetry in forward and backward connections was addressed by comparing dynamic causal models of MEG responses induced by visual processing of normal and scrambled faces. We compared models with and without nonlinear (between-frequency) coupling in both forward and backward connections. Bayesian model comparison indicated that the best model had nonlinear forward and backward connections. Using the best model we then quantified frequency-specific causal influences mediating observed spectral responses. We found a striking asymmetry between forward and backward connections; in which high (gamma) frequencies in higher cortical areas suppressed low (alpha) frequencies in lower areas. This suppression was significantly greater than the homologous coupling in the forward connections. Furthermore, exactly the asymmetry was observed when we examined face-selective coupling (i.e., coupling under faces minus scrambled faces). These results highlight the importance of nonlinear coupling among brain regions and point to a functional asymmetry between forward and backward connections in the human brain that is consistent with anatomical and physiological evidence from animal studies. This asymmetry is also consistent with functional architectures implied by theories of perceptual inference in the brain, based on hierarchical generative models. (c) 2008 Elsevier Inc. All rights reserved.