BRAINSTEM MODULATION OF THE HIPPOCAMPUS

在早期的报告1，2中，我们确定了 高活动性大鼠桥脑网状结构 与海马体的theta节律相关。在随后的 研究3，4我们表明，电刺激相同的PRF 该区域产生了明显的海马theta。在映射 脑干对海马体的同步(Theta)效应， 我们还证明了刺激中缝中缝(MR)。 核团使海马区EEG.4去同步化。 PRF(主要是脑桥口侧核)和MR直接 参与海马区同步化状态的产生 分别去同步化。我们最新的工作是5-9 集中在解剖学上定义的PRF和MR通路到 内侧隔-斜角带核垂直支(MS-DBV)- -直接控制起搏细胞的位置 海马区脑电。简而言之，我们已经展示了明显的 从MR到MS-DBV的投影，但很少直接 从PRF到MS-DBV的投影。我们现在建议 乳头上核(SUM)可能是重要的纽带 在参与海马Theta区的PRF和MS-DBV之间 一代。 拟议的研究旨在准确定义脑干 隔-海马区系统参与控制脑电活动状态 海马区同步化和去同步化。具体来说， 我们打算研究：(1)单位活动之间的关系 行为大鼠海马区脑电的PRF、MR和SUM； 同样的三个核的细胞破坏对细胞的影响 海马区脑电；(3)PRF的传入；(4)PRF投射 到总和；(5)MR和总和到包含聊天的小区的投影 MS-DBV和(6)5-羟色胺和非5-羟色胺中位数的分布 将中缝纤维连接到MS-DBV。 最近的几个报告10-17表明，海马区的长期 增强(LTP)的最佳诱导方式是刺激theta 频率，并提出了theta节律可以 代表记忆的内生系统。10，11，14-18到我们的 知识，我们的实验室是目前唯一一个 考察题元节奏产生的根源(S) 在脑干内。如果，如上所述，西塔被证明是 与记忆密切相关，我们认为重要的是 充分了解导致其产生的神经机制。

In early reports 1,2 we identified a population of cells within the pontine reticular formation (PRF) of the rat with activity highly correlated with the theta rhythm of the hippocampus. In subsequent studies 3,4 we showed that electrical stimulation of this same PRF region produced pronounced hippocampal theta. In mapping the brainstem for its synchronizing (theta) effects on the hippocampus, we also demonstrated that stimulation of the median raphe (MR) nucleus desynchronized the hippocampal EEG.4 We proposed that the PRF (predominantly nucleus pontis oralis) and the MR are directly involved in generating states of hippocampal synchronization and desynchronization, respectively. Our most recent work 5-9 has concentrated on anatomically defining PRF and MR pathways to the medial septum-vertical limb of the diagonal band nuclei (MS-DBv) - - the site of the pacemaking cells that directly control the hippocampal EEG. In brief, we have demonstrated pronounced projections from the MR to the MS-DBv, but very few direct projections from the PRF to the MS-DBv. We now suggest that the supramammillary nucleus (SUM) may serve as an important link between the PRF and the MS-DBv involved in hippocampal theta generation. The proposed studies are designed to precisely define brainstem to septohippocampal systems involved in controlling states of hippocampal synchronization and desynchronization. Specifically, we intend to examine: (1) the relationship of unit activity in the PRF, MR and SUM to the hippocampal EEG in the behaving rat; (2) the effects of cellular destruction of these same three nuclei on the hippocampal EEG; (3) afferents to the PRF; (4) PRF projections to the SUM; (5) MR and SUM projections to ChAT-containing cells of the MS-DBv and (6) the distribution of 5-HT and non 5-HT median raphe fibers to the MS-DBv. Several recent reports 10-17 have shown that hippocampal long term potentiation (LTP) is optimally induced with stimulation at theta frequency and it has been suggested that the theta rhythm may represent an endogenous system for memory.10,11,14-18 To our knowledge, our laboratory is the only one that is currently examining the source(s) for the generation of the theta rhythm within the brainstem. If, as indicated, theta proves to be critically involved in memory, we believe that it is important to fully understand neural mechanisms responsible for its generation.