Department of Physiology, The University of Tokyo School of Medicine, Tokyo, Japan.
Cereb Cortex. 2011 Oct;21(10):2348-56. doi: 10.1093/cercor/bhr019. Epub 2011 Mar 2.
Correlated spontaneous activity in the resting brain is increasingly recognized as a useful index for inferring underlying functional-anatomic architecture. However, despite efforts for comparison with anatomical connectivity, neuronal origin of intrinsic functional connectivity (inFC) remains unclear. Conceptually, the source of inFC could be decomposed into causal components that reflect the efficacy of synaptic interactions and other components mediated by collective network dynamics (e.g., synchronization). To dissociate these components, it is useful to introduce another connectivity measure such as effective connectivity, which is a quantitative measure of causal interactions. Here, we present a direct comparison of inFC against emEC (effective connectivity probed with electrical microstimulation [EM]) in the somatosensory system of macaque monkeys. Simultaneous EM and functional magnetic resonance imaging revealed strong emEC in several brain regions in a manner consistent with the anatomy of somatosensory system. Direct comparison of inFC and emEC revealed colocalization and overall positive correlation within the stimulated hemisphere. Interestingly, we found characteristic differences between inFC and emEC in their interhemispheric patterns. Our results suggest that intrahemispheric inFC reflects the efficacy of causal interactions, whereas interhemispheric inFC may arise from interactions akin to network-level synchronization that is not captured by emEC.
大脑静息状态下的相关自发活动逐渐被认为是推断潜在功能-解剖结构的有用指标。然而，尽管已经努力与解剖连通性进行比较，但内在功能连通性（inFC）的神经元起源仍不清楚。从概念上讲，inFC 的来源可以分解为反映突触相互作用效率的因果成分，以及由集体网络动力学（例如同步）介导的其他成分。为了分离这些成分，引入另一种连通性度量（例如有效连通性）来衡量因果相互作用是很有用的。在这里，我们在猕猴的体感系统中直接比较了 inFC 与 emEC（用电极微刺激[EM]探测的有效连通性）。同时进行的 EM 和功能磁共振成像显示，在几个脑区中存在与体感系统解剖结构一致的强烈 emEC。inFC 和 emEC 的直接比较显示，在刺激半球内存在共定位和总体正相关。有趣的是，我们发现 inFC 和 emEC 在其半球间模式上存在特征差异。我们的结果表明，半球内的 inFC 反映了因果相互作用的效率，而半球间的 inFC 可能来自于类似于网络级同步的相互作用，而 emEC 无法捕捉到这种相互作用。
