Rolls E T
Department of Experimental Psychology, University of Oxford, England.
Hippocampus. 1996;6(6):601-20. doi: 10.1002/(SICI)1098-1063(1996)6:6<601::AID-HIPO5>3.0.CO;2-J.
First, what is computed by the hippocampus is considered. Based on the effects of damage to the hippocampus and neuronal activity recorded in the primate hippocampus, it is suggested that it is involved in associating together information usually originating from different cortical regions, for example, about objects and their place in a spatial environment. The rapid formation of such context-dependent memories is prototypical of memories of particular events or episodes. Second, a computational theory of how it performs this function, based on neuroanatomical and neurophysiological information about the different neuronal systems contained within the hippocampus, is described. Key hypotheses are that the CA3 pyramidal cells operate as a single autoassociation network to store new episodic information as it arrives via a number of specialized preprocessing stages from many different association areas of the cerebral cortex, and that the dentate granule cell/mossy fiber system is important particularly during learning to help to produce a new pattern of firing in the CA3 cells for each episode. The computational analysis shows how many memories could be stored in the hippocampus, and how quickly the CA3 autoassociation system would operate during recall. The analysis is then extended to show how the CA3 system could be used to recall the whole of an episodic memory when only a fragment of it is presented. It is shown how this retrieval within the hippocampus could lead to recall of neuronal activity in association areas of the cerebral neocortex similar to that present during the original episode, via modified synapses in backprojection pathways from the hippocampus to the cerebral neocortex. The recalled information in the cerebral neocortex could then by used by the neocortex in the formation of long-term memories and/or in the selection of appropriate actions.
首先，我们考虑海马体所计算的内容。基于对海马体损伤的影响以及在灵长类动物海马体中记录的神经元活动，有人提出海马体参与将通常源自不同皮质区域的信息关联在一起，例如，关于物体及其在空间环境中的位置的信息。这种依赖于情境的记忆的快速形成是特定事件或情节记忆的典型特征。其次，描述了一种基于关于海马体内不同神经元系统的神经解剖学和神经生理学信息的计算理论，说明它如何执行此功能。关键假设是，CA3锥体细胞作为一个单一的自联想网络运行，在新的情景信息通过多个专门的预处理阶段从大脑皮质的许多不同联合区域到达时存储这些信息，并且齿状颗粒细胞/苔藓纤维系统在学习过程中特别重要，有助于为每个情节在CA3细胞中产生新的放电模式。计算分析表明海马体可以存储多少记忆，以及CA3自联想系统在回忆过程中运行的速度有多快。然后分析进一步扩展，以说明当仅呈现情节记忆的一部分时，CA3系统如何用于回忆整个情节记忆。研究表明，通过海马体到大脑新皮质的反向投射通路中经过修饰的突触，海马体内的这种检索如何导致大脑新皮质联合区域中的神经元活动回忆，类似于原始情节中出现的活动。然后，大脑新皮质中回忆的信息可被新皮质用于形成长期记忆和/或选择适当的行动。
