Human frontal midline theta and its synchronization to gamma during a verbal delayed match to sample task
Human frontal midline theta and its synchronization to gamma during a verbal delayed match to sample task
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DOI：
10.1016/j.nlm.2009.09.013
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发表时间：
2010-02-01
影响因子：
2.7
通讯作者：
Sauseng, Paul
中科院分区：
文献类型：
--
作者：
Griesmayr, Birgit;Gruber, Walter R.;Sauseng, Paul
人类工作记忆中振荡活动的参与，尤其是 θ 和 γ 频率的振荡活动已被频繁报道。工作记忆期间的一个显着模式是脑电图额叶中线 theta 活动，有人建议它反映监测功能以处理任务。一般来说，theta 活动被认为具有分布式活动的综合功能。在本研究中，我们重点关注脑电图功率分析和跨频相位同步，以测试在执行口头延迟匹配样本任务期间，额叶中线 theta 活动是否与更多局部生成的伽马振荡相关。该任务包括两种不同的条件，受试者要么必须按字母顺序重新组织三个辅音字母（操作条件），要么只需要保留三个辅音字母（保留条件）。结果显示，与纯粹保留刺激材料相比，操纵维持刺激材料的额叶中线 θ 活性更高。有趣的是，不同条件之间的功率差异在延迟期的后半段最为明显。另一方面，额叶中线 theta 活动和分布式 gamma 活动之间的跨频相位同步在延迟期的前半段占主导地位，并且与保留相比，操纵性更强。我们认为，额叶中线 theta 与伽马活动的耦合反映了对记忆项目时间分离的监测功能，而延迟期后半段较高的额叶中线 theta 功率可能与排练过程有关。操纵条件下的排练过程可能更加明显，因为与纯粹的保留相比，在有限的时间窗口内排练新的字母串需要更高的脑力劳动，其中排练过程可能已经在延迟期开始时开始。 (C) 2009 Elsevier Inc. 保留所有权利。
The involvement of oscillatory activity, especially at theta and gamma frequency, in human working memory has been reported frequently. A salient pattern during working memory is electroencephalographic frontal midline theta activity which has been suggested to reflect monitoring functions in order to deal with a task. In general, theta activity has been credited with integrative functions of distributed activity. In the present study, we focused on electroencephalographic power analyses and cross-frequency phase synchronization in order to test whether frontal midline theta activity is linked to more locally generated gamma oscillations during the performance of a verbal delayed match to sample task. The task consisted of two different conditions where subjects either had to reorganize three consonant letters in alphabetical order (manipulation condition) or where they merely had to retain the three consonant letters (retention condition). Results revealed higher frontal midline theta activity for the manipulation of maintained stimulus material compared to pure retention of stimulus material. Interestingly, power differences between conditions were most pronounced during the second half of the delay period. Cross-frequency phase synchronization between frontal midline theta activity and distributed gamma activity, on the other hand, was predominant during the first half of the delay period and was stronger for manipulation compared to retention. We suggest that coupling of frontal midline theta to gamma activity reflects monitoring functions on the temporal segregation of memory items, whereas higher frontal midline theta power in the second half of the delay period might be associated with rehearsal processes. Rehearsal processes in the manipulation condition are likely more pronounced, because rehearsal of a new letter string in a limited time window requires higher mental effort compared to pure retention where rehearsal processes may already start at the beginning of the delay period. (C) 2009 Elsevier Inc. All rights reserved.