Sustained neural activity patterns during working memory in the human medial temporal lobe
Sustained neural activity patterns during working memory in the human medial temporal lobe
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DOI：
10.1523/jneurosci.0962-07.2007
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发表时间：
2007-07-18
影响因子：
5.3
通讯作者：
Fell, Juergen
中科院分区：
文献类型：
--
作者：
Axmacher, Nikolai;Mormann, Florian;Fell, Juergen
与内侧颞叶 (MTL) 特别是长期记忆的基础的经典研究结果相反，之前的数据表明 MTL 结构也可能有助于工作记忆 (WM)。然而，MTL 支持 WM 的神经机制仍然未知。在这里，我们利用颅内脑电图来识别 WM 特定的持续活动模式，并具有目前人类可用的最高时间和空间分辨率。使用串行 Sternberg 范式，我们发现在维护单个项目期间，直流 (DC) 电势发生正向变化，并且 MTL 伽马能带活性长期持续下降，这反映了神经活动的持续减少。维护越来越多的物品会引起直流电势的逐渐负移和 MTL 伽马带活动的增加。此外，该范例是使用功能磁共振成像在健康对照受试者中进行的。这证实了我们的结果不是由 MTL 内的病理过程引起的，并且该区域确实在任务期间被专门激活。因此，我们的结果为 MTL 工作记忆维持期间持续的神经活动模式提供了直接证据，并表明这些模式取决于 WM 负载。
In contrast to classical findings that the medial temporal lobe (MTL) specifically underlies long-term memory, previous data suggest that MTL structures may also contribute to working memory (WM). However, the neural mechanisms by which the MTL supports WM have remained unknown. Here, we exploit intracranial EEG to identify WM-specific sustained activity patterns with the highest temporal and spatial resolution currently available in humans. Using a serial Sternberg paradigm, we found a positive shift of the direct current (DC) potential and a long-lasting decrease in MTL gamma-bandactivity during maintenance of a single item, reflective of a sustained reduction in neural activity. Maintenance of an increasing number of items elicited an incrementally negative shift of the DC potential and an increase in MTL gamma-band activity. In addition, the paradigm was conducted in healthy control subjects using functional magnetic resonance imaging. This confirmed that our results were not caused by pathological processes within the MTL, and that this region was indeed specifically activated during the task. Our results thus provide direct evidence for sustained neural activity patterns during working memory maintenance in the MTL, and show that these patterns depend on WM load.