Spatial and temporal heterogeneity of neural responses in human posteromedial cortex
Spatial and temporal heterogeneity of neural responses in human posteromedial cortex
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DOI：
10.1073/pnas.1721714115
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发表时间：
2018-05-01
影响因子：
11.1
通讯作者：
Parvizi, Josef
中科院分区：
文献类型：
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作者：
Daitch, Amy L.;Parvizi, Josef
神经影像学证据支持默认模式网络（DMN）在自发思维和目标驱动的内部导向过程中的作用，如回忆自传体事件，并已证明其在集中，外部导向的注意力。最近的研究表明，DMN不是一个同质的网络，而是由至少几个子网络组成，这些子网络参与不同的功能;然而，目前还不清楚这些不同的功能是否依赖于相同的神经元群体。在这项研究中，我们使用颅内脑电图记录从后内侧皮层（PMC），DMN的核心枢纽，在13名人类受试者，自传体记忆检索（内部导向），算术处理（外部导向），和线索休息（自发思维），使我们能够测量活动，从解剖学上精确的PMC网站与高时间分辨率。我们观察到一个异构的，但空间组织，跨任务的活动模式。许多网站，主要是在更腹侧部分的PMC，从事自传体回忆和抑制算术处理。其他更多的背PMC网站从事在线索休息条件。在这些休息-活动位点中，一些在试验中表现出可变的时间动态，可能反映了各种形式的自发思维，而另一些在提示-休息试验开始时仅表现出短暂的活动（即，从任务转换到暗示休息后），可能涉及将大脑从更专注的状态转换到更探索的注意力状态。这些结果表明即使在DMN的单个节点内功能也是异质性的。
Neuroimaging evidence supports a role of the default mode network (DMN) in spontaneous thought and goal-driven internally oriented processes, such as recalling an autobiographical event, and has demonstrated its deactivation during focused, externally oriented attention. Recent work suggests that the DMN is not a homogeneous network but rather is composed of at least several subnetworks, which are engaged in distinct functions; however, it is still unclear if these different functions rely on the same neuronal populations. In this study, we used intracranial EEG to record from the posteromedial cortex (PMC), a core hub of the DMN, in 13 human subjects, during autobiographical memory retrieval (internally oriented), arithmetic processing (externally oriented), and cued rest (spontaneous thought), allowing us to measure activity from anatomically precise PMC sites with high temporal resolution. We observed a heterogeneous, yet spatially organized, pattern of activity across tasks. Many sites, primarily in the more ventral portion of PMC, were engaged during autobiographical recall and suppressed during arithmetic processing. Other more dorsal PMC sites were engaged during the cued-rest condition. Of these rest-active sites, some exhibited variable temporal dynamics across trials, possibly reflecting various forms of spontaneous thought, while others showed only transient activity at the beginning of cued-rest trials (i.e., after a switch from a task to cued rest), possibly involved in shifting the brain from a more focused to a more exploratory attentional state. These results suggest heterogeneity of function even within an individual node of the DMN.