Hippocampal memory consolidation during sleep: a comparison of mammals and birds.
Hippocampal memory consolidation during sleep: a comparison of mammals and birds.
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DOI：
10.1111/j.1469-185x.2010.00165.x
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发表时间：
2011-08
影响因子：
--
通讯作者：
Pravosudov VV
中科院分区：
文献类型：
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作者：
Rattenborg NC;Martinez-Gonzalez D;Roth TC 2nd;Pravosudov VV
从清醒到睡眠的过渡是以大脑活动的显著变化为标志的。慢波睡眠（SWS）和快速眼动睡眠（REM）是哺乳动物睡眠的两种主要类型，它们的大脑节律被认为与睡眠功能有关。特别是，最近的理论表明，新皮层神经元膜电位的同步慢振荡（SWS的定义特征）参与了在清醒期间获得的信息的处理。根据记忆巩固的标准模型，在清醒期间，海马体接收来自参与经验初始编码的新皮质区域的输入，并将这些信息绑定到一个连贯的记忆痕迹中，然后在SWS期间转移到新皮质，在那里它被存储并整合到先前存在的记忆痕迹中。有证据表明，这一过程选择性地涉及海马体与前额叶皮层（PFC）之间的直接连接，前额叶皮层是一个多模态、高阶的关联区域，涉及协调新皮层中远程记忆的存储和回忆。慢振荡被认为是通过海马尖波/波纹（SWRs）和丘脑皮质纺锤波的暂时耦合来协调海马的信息传递。swr是海马活动的同步爆发，在此期间，海马和新皮层以协调的方式重新激活清醒的神经元放电模式。丘脑皮层纺锤波是短暂的7-14赫兹振荡，可能有助于在swr期间重新激活的信息编码。通过暂时耦合从海马体读出的信息与有利于在新皮层编码的条件，慢振荡被认为是介导信息从海马体到新皮层的传递。虽然有几条证据表明哺乳动物的SWS具有这种功能，但目前尚不清楚SWS是否在鸟类中具有类似的功能，鸟类是除哺乳动物外唯一表现出SWS和REM睡眠的分类群体。根据我们对鸟类睡眠、神经解剖学和记忆研究的回顾，尽管鸟类睡眠涉及某些形式的记忆巩固，但似乎并不涉及将海马记忆转移到其他大脑区域。尽管表现出缓慢振荡，但在鸟类中没有发现swr和纺锤体。此外，尽管鸟类独立进化出一个大脑区域——尾侧nidopallium （NCL）——参与执行类似于PFC执行的高阶认知功能，但在鸟类中还没有发现NCL和海马之间的直接联系，并且缺乏从海马向NCL或其他海马体外区域传递信息的证据。尽管缺乏各种特征的证据，但总的来说，这些发现表明，与哺乳动物的SWS不同，鸟类的SWS可能不涉及从海马体转移记忆。此外，该研究还表明，哺乳动物和鸟类SWS的定义特征——慢振荡，可能具有更普遍的功能，独立于哺乳动物海马向PFC协调信息传递的功能。鉴于哺乳动物和鸟类的SWS是动态调节的（一个与慢振荡密切相关的过程），与这一过程相关的功能假设可能适用于这两个分类类群。
The transition from wakefulness to sleep is marked by pronounced changes in brain activity. The brain rhythms that characterize the two main types of mammalian sleep, slow-wave sleep (SWS) and rapid eye movement (REM) sleep, are thought to be involved in the functions of sleep. In particular, recent theories suggest that the synchronous slow-oscillation of neocortical neuronal membrane potentials, the defining feature of SWS, is involved in processing information acquired during wakefulness. According to the Standard Model of memory consolidation, during wakefulness the hippocampus receives input from neocortical regions involved in the initial encoding of an experience and binds this information into a coherent memory trace that is then transferred to the neocortex during SWS where it is stored and integrated within preexisting memory traces. Evidence suggests that this process selectively involves direct connections from the hippocampus to the prefrontal cortex (PFC), a multimodal, high-order association region implicated in coordinating the storage and recall of remote memories in the neocortex. The slow-oscillation is thought to orchestrate the transfer of information from the hippocampus by temporally coupling hippocampal sharp-wave/ripples (SWRs) and thalamocortical spindles. SWRs are synchronous bursts of hippocampal activity, during which waking neuronal firing patterns are reactivated in the hippocampus and neocortex in a coordinated manner. Thalamocortical spindles are brief 7–14 Hz oscillations that may facilitate the encoding of information reactivated during SWRs. By temporally coupling the readout of information from the hippocampus with conditions conducive to encoding in the neocortex, the slow-oscillation is thought to mediate the transfer of information from the hippocampus to the neocortex. Although several lines of evidence are consistent with this function for mammalian SWS, it is unclear whether SWS serves a similar function in birds, the only taxonomic group other than mammals to exhibit SWS and REM sleep. Based on our review of research on avian sleep, neuroanatomy, and memory, although involved in some forms of memory consolidation, avian sleep does not appear to be involved in transferring hippocampal memories to other brain regions. Despite exhibiting the slow-oscillation, SWRs and spindles have not been found in birds. Moreover, although birds independently evolved a brain region – the caudolateral nidopallium (NCL) – involved in performing high-order cognitive functions similar to those performed by the PFC, direct connections between the NCL and hippocampus have not been found in birds, and evidence for the transfer of information from the hippocampus to the NCL or other extra-hippocampal regions is lacking. Although based on the absence of evidence for various traits, collectively, these findings suggest that unlike mammalian SWS, avian SWS may not be involved in transferring memories from the hippocampus. Furthermore, it suggests that the slow-oscillation, the defining feature of mammalian and avian SWS, may serve a more general function independent of that related to coordinating the transfer of information from the hippocampus to the PFC in mammals. Given that SWS is homeostatically regulated (a process intimately related to the slow-oscillation) in mammals and birds, functional hypotheses linked to this process may apply to both taxonomic groups.