Perirhinal cortex input to the hippocampus in the rat: evidence for parallel pathways, both direct and indirect. A combined physiological and anatomical study
Perirhinal cortex input to the hippocampus in the rat: evidence for parallel pathways, both direct and indirect. A combined physiological and anatomical study
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DOI：
10.1046/j.1460-9568.1999.00835.x
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发表时间：
1999-11-01
影响因子：
3.4
通讯作者：
da Silva, FHL
中科院分区：
文献类型：
--
作者：
Naber, PA;Witter, MP;da Silva, FHL
在示踪剂研究的基础上，已经提出了从口周皮质(PER)直接投射到海马区CA1和下丘脑(SUB)的可能性，但这一投射并未得到生理学研究的明确支持。这种功能通路的演示对于理解海马体记忆系统的功能可能很重要。在这里，我们提供了生理学和进一步的解剖学证据，证明PER和海马体之间存在这种联系。电刺激CA1/SUB交界区的PER体内诱发电位(EFP)，由短潜伏期和长潜伏期组成。电流源密度分析表明，短潜伏期成分的汇点位于CA1/SUB区的分子层，而长潜伏期成分的汇点位于齿状回(DG)的外层分子层。PER顺行示踪剂注射显示CA1/SUB交界区有标记纤维，但未发现PER向DG投射的解剖学证据。当内嗅皮层的突触传递被部分阻断时，记录到的海马区EFP的长潜伏期成分的幅度降低，而短潜伏期成分的幅度不受影响，这表明起源于PER的间接通路是通过内嗅背核的突触传递介导的。根据目前的结果，我们得出结论，起源于PER的信息通过平行的、直接的和间接的路线到达CA1/SUB区。这种平行组织的存在似乎形成了内侧颞叶记忆系统正常功能的基本特征。
The possibility of a direct projection from the perirhinal cortex (PER) to areas CA1 and subiculum (SUB) in the hippocampus has been suggested on the basis of tracer studies, but this projection has not unequivocally been supported by physiological studies. The demonstration of such a functional pathway might be important to understand the functioning of the hippocampal memory system. Here we present physiological and further anatomical evidence for such a connection between PER and the hippocampus. Electrical stimulation of PER in vivo evoked field potentials (EFPs) at the border area of CA1/SUB, consisting of a short latency and a longer latency component. Current source density analysis revealed that the sink of the short latency component was situated in the molecular layer of area CA1/SUB, while the longer latency component had its sink in the outer molecular layer of the dentate gyrus (DG). Anterograde tracer injections in PER showed labelled fibres in the border area of CA1/SUB, but anatomical evidence for a projection of PER to DG was not found. When synaptic transmission in the entorhinal cortex was partly blocked, the amplitude of the longer latency component of the recorded EFPs in the hippocampus was decreased while the short latency component was not affected, which suggests that the indirect pathway originating in PER is mediated through a synaptic relay in the entorhinal dorter. From the present results we conclude that information originating in PER reaches area CA1/SUB by parallel, direct and indirect, routes. The existence of this parallel organization appears to form an essential feature for the proper function of the medial temporal lobe memory system.