Center for Brain and Cognition, Computational Neuroscience Group, Department of Information and Communication Technologies, Universitat Pompeu Fabra, Roc Boronat 138, Barcelona 08018, Spain.
Oxford Centre for Human Brain Activity, University of Oxford, Warneford Hospital, Oxford OX37JX, UK.
Neuroimage. 2015 Feb 1;106:328-39. doi: 10.1016/j.neuroimage.2014.10.057. Epub 2014 Oct 30.
In the absence of cognitive tasks and external stimuli, strong rhythmic fluctuations with a frequency ≈ 10 Hz emerge from posterior regions of human neocortex. These posterior α-oscillations can be recorded throughout the visual cortex and are particularly strong in the calcarine sulcus, where the primary visual cortex is located. The mechanisms and anatomical pathways through which local \alpha-oscillations are coordinated however, are not fully understood. In this study, we used a combination of magnetoencephalography (MEG), diffusion tensor imaging (DTI), and biophysical modeling to assess the role of white-matter pathways in coordinating cortical α-oscillations. Our findings suggest that primary visual cortex plays a special role in coordinating α-oscillations in higher-order visual regions. Specifically, the amplitudes of α-sources throughout visual cortex could be explained by propagation of α-oscillations from primary visual cortex through white-matter pathways. In particular, α-amplitudes within visual cortex correlated with both the anatomical and functional connection strengths to primary visual cortex. These findings reinforce the notion of posterior α-oscillations as intrinsic oscillations of the visual system. We speculate that they might reflect a default-mode of the visual system during which higher-order visual regions are rhythmically primed for expected visual stimuli by α-oscillations in primary visual cortex.
在没有认知任务和外部刺激的情况下，人类新皮质的后区域会出现频率约为 10 Hz 的强节奏波动。这些后α波可以在整个视觉皮层中记录到，在位于初级视觉皮层的枕骨沟中尤其强烈。然而，局部α波协调的机制和解剖途径尚不完全清楚。在这项研究中，我们结合使用了脑磁图（MEG）、弥散张量成像（DTI）和生物物理建模，以评估白质通路在协调皮质α波中的作用。我们的研究结果表明，初级视觉皮层在协调高级视觉区域的α波中起着特殊作用。具体而言，整个视觉皮层的α源振幅可以通过从初级视觉皮层传播的α波来解释。特别是，视觉皮层内的α波幅度与初级视觉皮层的解剖和功能连接强度都相关。这些发现加强了后α波是视觉系统固有振荡的概念。我们推测，它们可能反映了视觉系统的默认模式，在此期间，通过初级视觉皮层的α波，高级视觉区域为预期的视觉刺激做好了有节奏的准备。
