The supramammillary nucleus: Is it necessary for the mediation of hippocampal theta rhythm?
The supramammillary nucleus: Is it necessary for the mediation of hippocampal theta rhythm?
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DOI：
10.1016/0306-4522(95)00045-k
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发表时间：
1995-07
期刊：
影响因子：
3.3
通讯作者：
J. S. Thinschmidt;G. Kinney;Bernat Kocsis
中科院分区：
文献类型：
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作者：
J. S. Thinschmidt;G. Kinney;Bernat Kocsis
最近的证据表明，下丘脑后乳头体上核在参与海马theta节律产生的脑干至隔膜/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节律的可能中继/介体的作用，分别对自由活动和麻醉大鼠的乳头体上核进行电解损伤和普鲁卡因注射。在麻醉大鼠中，发现普鲁卡因注射减弱了刺激脑桥网状结构引起的θ节律的频率和振幅。这些数据表明，脑桥网状引出海马θ节律介导的乳头体上核的连接。然而，它被发现，乳头体上核的病变未能产生明显的变化，在海马脑电图的自由移动的动物。几种解释有关这种明显的差异进行了讨论。最引人注目的是，多个脑干到隔/海马通路可能有助于在自由运动的动物中产生或促进θ节律的产生。本报告表明，乳头体上核在海马脑电图信号的介导中起着可疑的作用，海马脑电图信号被认为是重要的记忆过程。
Recent evidence suggests that the supramammillary nucleus of the posterior hypothalamus serves as an important relay in the 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.