BRAINSTEM MODULATION OF THE HIPPOCAMPUS

在早期的报告中，我们发现了一个细胞群， 脑桥网状结构（PRF）的大鼠活动高度 与海马体的θ节律相关。 在随后 研究3，4表明，电刺激相同的PRF， 区域产生明显的海马theta。 在绘制 脑干对海马体的同步（θ）作用， 我们还证明了刺激中缝核（MR） 核使海马EEG去极化。4我们提出， PRF（主要是脑桥口核）和MR直接 参与产生海马同步状态， 分别进行去离子化。 我们最近的工作5-9有 集中在解剖学上定义PRF和MR通路， 内侧隔-斜角带核垂直支（MS-DBv）- - 直接控制心脏的起搏细胞的位置 海马脑电图 简而言之，我们已经证明了 从MR到MS-DBv的预测，但很少直接 从PRF到MS-DBv的预测。 我们现在建议， 乳头体上核（SUM）可能是一个重要的环节 参与海马theta区的PRF和MS-DBv之间 一代 拟议的研究旨在精确定义脑干， 隔海马系统参与控制状态 海马同步化和去同步化。 具体地说， 我们打算研究：（1）单位活动的关系， （2）对行为正常大鼠海马脑电的PRF、MR和SUM进行分析; 这三个核团的细胞破坏对 海马EEG;（3）到PRF的传入;（4）PRF投射 （5）MR和SUM向含ChAT细胞的投射， MS-DBv和（6）5-HT和非5-HT中位数的分布 与MS-DBv的联系 最近的一些报道10-17表明，海马长期 增强作用（LTP）最佳地由θ刺激诱导 频率，并已提出，θ节律可能 代表了一个记忆的内源系统。10，11，14 -18 知识，我们的实验室是目前唯一一个 检查θ节律产生的来源 在脑干内。如果，如前所述，θ被证明是 关键参与记忆，我们认为，这是重要的， 完全理解负责其产生的神经机制。

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.