Thinschmidt J S, Kinney G G, Kocsis B
Department of Neuroscience, University of Florida, College of Medicine, Gainesville 32610-0244, USA.
Neuroscience. 1995 Jul;67(2):301-12. doi: 10.1016/0306-4522(95)00045-k.
Recent evidence suggests that the supramammillary nucleus of the posterior hypothalamus serves as an important relay in a brainstem to septum/hippocampus pathway involved in the generation of hippocampal theta rhythm. In order to examine the role of the supramammillary nucleus as a possible relay/mediator of hippocampal theta rhythm, electrolytic lesions and procaine injections were administered to the supramammillary nucleus of freely moving and urethane-anesthetized rats, respectively. In the urethane-anesthetized rat, it was found that procaine injections attenuated both the frequency and amplitude of theta rhythm elicited by stimulation of the pontine reticular formation. These data suggest that the pontine reticular elicitation of hippocampal theta rhythm is mediated through connections with the supramammillary nucleus. However, it was found that lesions of the supramammillary nucleus failed to produce significant changes in the hippocampal electroencephalogram of freely moving animals. Several explanations concerning this apparent discrepancy are discussed. The most compelling is that multiple brainstem to septum/hippocampus pathways may serve to generate or facilitate the generation of theta rhythm in the freely moving animal. The present report demonstrates that the supramammillary nucleus plays a questionable role in the mediation of hippocampal electroencephalogram signals which are thought to be important for mnemonic processes.
最近的证据表明，下丘脑后部的乳头体上核在参与海马θ节律产生的脑干至隔区/海马通路中起着重要的中继作用。为了研究乳头体上核作为海马θ节律可能的中继/介导者的作用，分别对自由活动和氨基甲酸乙酯麻醉的大鼠的乳头体上核进行了电解损伤和普鲁卡因注射。在氨基甲酸乙酯麻醉的大鼠中，发现注射普鲁卡因会减弱由脑桥网状结构刺激引发的θ节律的频率和振幅。这些数据表明，脑桥网状结构对海马θ节律的引发是通过与乳头体上核的连接介导的。然而，发现乳头体上核的损伤并未使自由活动动物的海马脑电图产生显著变化。讨论了关于这种明显差异的几种解释。最有说服力的是，多条脑干至隔区/海马通路可能有助于在自由活动的动物中产生或促进θ节律的产生。本报告表明，乳头体上核在介导被认为对记忆过程很重要的海马脑电信号方面所起的作用值得怀疑。
