Oddie S D, Bland B H, Colom L V, Vertes R P
Department of Psychology, University of Calgary, Alberta, Canada.
Hippocampus. 1994 Aug;4(4):454-73. doi: 10.1002/hipo.450040408.
Electrical stimulation and microinfusion techniques were utilized in acute experiments on urethane-anesthetized rats in order to evaluate the hypothesis that the posterior hypothalamic and supramammillary nuclei comprise a critical part of the ascending brainstem pathway for producing synchronous hippocampal formation (HPC) field activity (theta). Given confirmation of this hypothesis a second objective was to determine the nature of the contribution made by this midline posterior hypothalamic region (PH) to the frequency and amplitude components of HPC theta field activity. The cholinergic nature of the ascending pathway was also examined. Reversible inactivation of the PH was achieved by microinfusion of the local anesthetic procaine hydrochloride. The efficacy of and recovery from procaine inactivation of the PH was quantitatively analyzed either by electrical stimulation of the nucleus pontis oralis (PO) (two experiments) or the PH (four experiments). The results are summarized under the following three headings: 1) The first is the effect of procaine inactivation of the PH on HPC theta elicited caudal to, at the level of, or rostral to the PH. All HPC theta induced caudal to the PH (spontaneous theta, tail pinch-induced theta, and theta produced by electrical stimulation of the PO) was totally abolished for a minimum 10-min period. HPC theta induced rostral to the PH by the intrahippocampal infusion of carbachol was unaffected, while HPC theta induced by infusions of carbachol into either the medial septum (MS) or PH was reduced in amplitude with no effect on frequency. 2) Next are comparisons of pre- and post-PH procaine trials of electrical stimulation of the PO and PH. In all experiments, regardless of the anatomical locus or technique used to induce HPC theta, pre- and post-PH procaine comparisons of the PO and PH stimulation trials revealed that frequency modulation of HPC theta recovered significantly more slowly than amplitude. 3) Last is the effect of electrical stimulation of the PO and PH on HPC theta induced by carbachol infusions at the level of the HPC, MS, or PH. In all experiments, electrical stimulation of both the PO and PH, at appropriate intensities, resulted in increasing HPC theta frequencies above the frequency induced by the infusion of carbachol into the HPC, MS, and PH. In addition, the post-carbachol HPC theta frequencies induced by electrical stimulation were significantly higher than those produced in the pre-carbachol conditions.(ABSTRACT TRUNCATED AT 400 WORDS)
在对氨基甲酸乙酯麻醉的大鼠进行的急性实验中，采用了电刺激和微量注射技术，以评估以下假设：下丘脑后部和乳头体上核构成了产生海马结构（HPC）同步场活动（θ波）的脑干上行通路的关键部分。若该假设得到证实，第二个目标是确定下丘脑后部中线区域（PH）对HPC θ场活动的频率和振幅成分的贡献性质。还研究了上行通路的胆碱能性质。通过微量注射局部麻醉药盐酸普鲁卡因实现PH的可逆失活。通过电刺激脑桥口腔核（PO）（两个实验）或PH（四个实验），对PH的普鲁卡因失活的效果和恢复情况进行了定量分析。结果总结如下三个标题：1）第一个是PH的普鲁卡因失活对在PH尾侧、PH水平或PH头侧诱发的HPC θ波的影响。在至少10分钟的时间内，所有在PH尾侧诱发的HPC θ波（自发θ波、尾部夹捏诱发的θ波以及电刺激PO产生的θ波）都完全消失。海马内注射卡巴胆碱在PH头侧诱发的HPC θ波不受影响，而向内侧隔区（MS）或PH注射卡巴胆碱诱发的HPC θ波振幅降低，频率无影响。2）接下来是对PO和PH电刺激的PH普鲁卡因注射前后试验的比较。在所有实验中，无论用于诱发HPC θ波的解剖部位或技术如何，PO和PH刺激试验的PH普鲁卡因注射前后比较显示HPC θ波频率调制的恢复明显比振幅恢复慢。3）最后是PO和PH电刺激对在HPC、MS或PH水平注射卡巴胆碱诱发的HPC θ波的影响。在所有实验中，以适当强度电刺激PO和PH均导致HPC θ波频率高于向HPC、MS和PH注射卡巴胆碱诱发的频率。此外，电刺激诱发的卡巴胆碱后HPC θ波频率显著高于卡巴胆碱前的频率。（摘要截断于400字）
