Axmacher Nikolai, Schmitz Daniel P, Weinreich Ilona, Elger Christian E, Fell Juergen
Department of Epileptology, University of Bonn, 53105 Bonn, Germany.
Cereb Cortex. 2008 Dec;18(12):2868-78. doi: 10.1093/cercor/bhn045. Epub 2008 Apr 9.
Recent findings indicate that regions in the medial temporal lobe (MTL) do not only play a crucial role in long-term memory (LTM) encoding, but contribute to working memory (WM) as well. However, very few studies investigated the interaction between these processes so far. In a new functional magnetic resonance imaging paradigm comprising both a complex WM task and an LTM recognition task, we found not only that some items were successfully processed in WM but later forgotten, but also that a significant number of items which were not successfully processed in the WM task were subsequently recognized. Activation in the parahippocampal cortex (PHC) during successful WM was predictive of subsequent LTM, but was correlated with subsequent forgetting if the WM task was not successfully solved. The contribution of the PHC to LTM encoding thus crucially depends on whether an item was successfully processed in the WM task. Functional connectivity analysis revealed that across-trial fluctuations in PHC activity were correlated with activation in extensive regions if WM and LTM tasks were correctly solved, whereas connectivity broke down during unsuccessful attempts to do the task, suggesting that activity in the PHC during WM has to be well controlled to support LTM formation.
最近的研究结果表明，内侧颞叶（MTL）区域不仅在长期记忆（LTM）编码中起关键作用，而且对工作记忆（WM）也有贡献。然而，到目前为止，很少有研究调查这些过程之间的相互作用。在一个新的功能磁共振成像范式中，该范式包括一个复杂的工作记忆任务和一个长期记忆识别任务，我们发现不仅一些项目在工作记忆中得到了成功处理，但后来被遗忘了，而且大量在工作记忆任务中未得到成功处理的项目随后被识别出来。在成功的工作记忆过程中海马旁回皮质（PHC）的激活可预测随后的长期记忆，但如果工作记忆任务未成功解决，则与随后的遗忘相关。因此，海马旁回皮质对长期记忆编码的贡献关键取决于一个项目在工作记忆任务中是否得到了成功处理。功能连接分析显示，如果工作记忆和长期记忆任务得到正确解决，海马旁回皮质活动的跨试验波动与广泛区域的激活相关，而在执行任务的不成功尝试中连接性则会中断，这表明工作记忆过程中海马旁回皮质的活动必须得到良好控制以支持长期记忆的形成。
