Direct Comparison of Spontaneous Functional Connectivity and Effective Connectivity Measured by Intracortical Microstimulation: An fMRI Study in Macaque Monkeys
Direct Comparison of Spontaneous Functional Connectivity and Effective Connectivity Measured by Intracortical Microstimulation: An fMRI Study in Macaque Monkeys
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DOI：
10.1093/cercor/bhr019
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发表时间：
2011-10-01
期刊：
影响因子：
3.7
通讯作者：
Miyashita, Yasushi
中科院分区：
文献类型：
--
作者：
Matsui, Teppei;Tamura, Keita;Miyashita, Yasushi
相关的自发活动，在休息的大脑越来越多地被认为是一个有用的指标，推断潜在的功能解剖结构。然而，尽管努力与解剖连接比较，内在功能连接（inFC）的神经元起源仍然不清楚。从概念上讲，inFC的来源可以分解为反映突触相互作用的功效的因果成分和由集体网络动态介导的其他成分（例如，同步）。为了分离这些成分，引入另一种连接性度量是有用的，例如有效连接性，它是因果相互作用的定量度量。在这里，我们提出了一个直接比较inFC对emEC（有效连接探测电微刺激[EM]）在猕猴的体感系统。同时EM和功能磁共振成像显示，强烈的emEC在几个大脑区域的方式符合解剖的躯体感觉系统。inFC和emEC的直接比较显示共定位和整体的正相关性内的刺激半球。有趣的是，我们发现inFC和emEC在其半球间模式的特征差异。我们的研究结果表明，半球内的inFC反映因果相互作用的疗效，而半球间的inFC可能会出现类似于网络水平的同步，是不是由emEC捕获的相互作用。
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.