The mechanisms for pattern completion and pattern separation in the hippocampus.
The mechanisms for pattern completion and pattern separation in the hippocampus.
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DOI：
10.3389/fnsys.2013.00074
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发表时间：
2013-10-30
影响因子：
3
通讯作者：
Rolls ET
中科院分区：
文献类型：
--
作者：
Rolls ET
模式完成和模式分离的机制是在海马体功能理论的背景下描述的，其中海马体CA3系统作为一个单一的吸引子或自动关联网络运行，以实现任何空间位置（啮齿动物的位置或灵长类动物的空间视图）与物体或奖励之间的快速、一次试验的关联，并提供在回忆任何部分时完成整个记忆。CA3模式完成以及大量独立记忆存储在CA3中的重要因素包括：稀疏分布表征（由CA3神经元的分级放电率增强）、苔藓纤维的随机效应导致的独立表征、异突触长期抑制以及反复侧联突触的长期增强。并稀释连接性，以尽量减少任何一对CA3神经元之间的多个突触的数量，否则会扭曲吸引力盆地。来自CA3的信息的回忆是由内嗅皮层到CA3细胞的穿孔通路突触实现的，CA3细胞作为一种模式联想器，允许一些模式泛化。在齿状颗粒细胞中进行模式分离，使用竞争学习将网格状内嗅皮层放电转换为位置状场。CA3中的模式分离对于从片段中完成任何一种存储模式都很重要，这是由苔藓纤维突触的随机效应提供的，神经发生可能有助于这种随机效应，由大量具有稀疏表示的齿状颗粒细胞提供，以及由CA3中的稀疏独立表示提供。对新皮层的回忆是通过海马-皮层反向投射实现的一系列反向分层模式关联网络来实现的，每个模式关联网络都执行一些模式泛化，以检索高阶皮层区域的完整皮层放电模式。
The mechanisms for pattern completion and pattern separation are described in the context of a theory of hippocampal function in which the hippocampal CA3 system operates as a single attractor or autoassociation network to enable rapid, one-trial, associations between any spatial location (place in rodents, or spatial view in primates) and an object or reward, and to provide for completion of the whole memory during recall from any part. The factors important in the pattern completion in CA3 together with a large number of independent memories stored in CA3 include a sparse distributed representation which is enhanced by the graded firing rates of CA3 neurons, representations that are independent due to the randomizing effect of the mossy fibers, heterosynaptic long-term depression as well as long-term potentiation in the recurrent collateral synapses, and diluted connectivity to minimize the number of multiple synapses between any pair of CA3 neurons which otherwise distort the basins of attraction. Recall of information from CA3 is implemented by the entorhinal cortex perforant path synapses to CA3 cells, which in acting as a pattern associator allow some pattern generalization. Pattern separation is performed in the dentate granule cells using competitive learning to convert grid-like entorhinal cortex firing to place-like fields. Pattern separation in CA3, which is important for completion of any one of the stored patterns from a fragment, is provided for by the randomizing effect of the mossy fiber synapses to which neurogenesis may contribute, by the large number of dentate granule cells each with a sparse representation, and by the sparse independent representations in CA3. Recall to the neocortex is achieved by a reverse hierarchical series of pattern association networks implemented by the hippocampo-cortical backprojections, each one of which performs some pattern generalization, to retrieve a complete pattern of cortical firing in higher-order cortical areas.