Theta oscillations index human hippocampal activation during a working memory task
Theta oscillations index human hippocampal activation during a working memory task
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DOI：
10.1073/pnas.97.2.919
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发表时间：
2000-01-18
影响因子：
11.1
通讯作者：
Karhu, J
中科院分区：
文献类型：
--
作者：
Tesche, CD;Karhu, J
工作记忆（WM）是在短时间内保持和关联信息的能力。功能成像研究表明，WM是由一个分布式网络，包括额叶和后皮质，海马和小脑介导的。在啮齿动物中，在WM任务中呈现刺激之后是海马theta相位的重置。在本文中，我们报告了一个类似的现象，在正常人的观察。在呈现一组数字和随后的保留项目的探测过程中记录神经磁反应。所有的刺激都以固定的时间模式呈现。我们观察到相位重置约7 Hz θ在左侧海马约120毫秒后探头刺激，而重置θ在右侧海马是可见的约80毫秒前，这些预期的刺激。刺激锁定θ波的持续时间随记忆负荷的增加而增加，5-7个保留项目的极限值约为600 ms。我们认为，在大鼠中，刺激锁定θ可能是人类海马网络参与感觉输入的认知处理的指标。θ的预期相位重置表明海马参与了右半球和小脑的计时网络。海马结构是必不可少的方向扰动的感觉场景，一个功能，需要使用的背景下建立的星座的刺激，我们认为，启动和维持刺激锁定海马θ这里观察到的可能有利于处理潜在的显着和/或新的输入相对于建立的上下文的WM的内容。
Working memory (WM) is the ability to retain and associate information over brief time intervals. Functional imaging studies demonstrate that WM is mediated by a distributed network including frontal and posterior cortices, hippocampus, and cerebellum. In rodents, the presentation of stimuli in a WM task is followed by a reset of the phase of hippocampal theta. In this paper we report the observation of a similar phenomenon in normal human subjects. Neuromagnetic responses were recorded during presentation of a set of digits and a subsequent probe of the retained items. All stimuli were presented with a fixed temporal pattern. We observed phase reset of approximate to 7 Hz theta in left hippocampus approximate to 120 ms after probe stimuli, whereas reset of theta in right hippocampus was visible approximate to 80 ms prior to these anticipated stimuli. The duration of stimulus-locked theta increased with memory load, with a limiting value of approximate to 600 ms for 5-7 retained items. We suggest that, as in rats, stimulus-locked theta may index involvement of human hippocampal networks in the cognitive processing of sensory input. The anticipatory phase reset of theta indicates involvement of hippocampus in right hemisphere and cerebellar timing networks. Hippocampal structures are essential for orientation to perturbations in the sensory scene, a function that requires use of a context established by a constellation of stimuli, We suggest that the initiation and maintenance of stimulus-locked hippocampal theta observed here may facilitate processing of potentially salient and/or novel input with respect to a context established by the contents of WM.