Colom L V, Nassif-Caudarella S, Dickson C T, Smythe J W, Bland B H
Department of Psychology, University of Calgary, Alberta, Canada.
Hippocampus. 1991 Oct;1(4):381-90. doi: 10.1002/hipo.450010406.
In their laboratory the authors have previously demonstrated that hippocampal slices could be induced to generate trains of "theta-like" oscillations by whole-bath perfusions of carbachol. Until recently, it has not been possible to generate similar activity in the septally deafferented hippocampus of an otherwise intact brain by microinfusions of carbachol. This study presents a full report of the first demonstration of a theta-like oscillation in the in vivo, septally deafferented hippocampal formation. Rats were anesthetized with urethane and implanted with microinfusion cannulae in the region of the medial septum/vertical limb of the diagonal band of Broca (MS/vDBB) and at single or multiple sites in the stratum moleculare of the fascia dentata. The MS/vDBB was microinfused with procaine hydrochloride to produce a reversible suppression lasting for approximately 20 minutes. Intrahippocampal microinfusions of carbachol or bicuculline alone (in the postprocaine condition of the MS/vDBB) failed to produce any theta-like oscillations. The combination of carbachol and bicuculline produced trains of theta-like oscillations during suppression of the MS/vDBB very similar to those seen in the slice preparations. The oscillations were blocked by intravenous administration of atropine sulfate, and they had the same depth profile as that of theta. Theta-on cells were shown to discharge in rhythmic bursts in synchrony with the oscillations. Thus, it would appear that the essential nature of the medial septal input to the hippocampal formation, for the generation of theta field activity in the intact brain, consists of a critical balance between cholinergic and GABAergic circuitry.
在他们的实验室中，作者们之前已经证明，通过向全脑灌注卡巴胆碱，可以诱导海马切片产生一系列“类θ波”振荡。直到最近，通过向原本完整大脑的隔区去传入海马体微量注射卡巴胆碱来产生类似活动仍是不可能的。本研究全面报告了首次在体内隔区去传入海马结构中证明类θ波振荡的情况。用乌拉坦麻醉大鼠，并在布罗卡斜角带内侧隔区/垂直支（MS/vDBB）区域以及齿状回分子层的单个或多个位点植入微量注射套管。向MS/vDBB微量注射盐酸普鲁卡因以产生持续约20分钟的可逆性抑制。单独向海马内微量注射卡巴胆碱或荷包牡丹碱（在MS/vDBB的普鲁卡因处理后状态下）未能产生任何类θ波振荡。卡巴胆碱和荷包牡丹碱的组合在抑制MS/vDBB期间产生了一系列类θ波振荡，与在切片制备中看到的非常相似。这些振荡被静脉注射硫酸阿托品阻断，并且它们具有与θ波相同的深度分布。θ波开启细胞被证明与振荡同步以节律性爆发的方式放电。因此，对于在完整大脑中产生θ场活动而言，海马结构内侧隔区输入的本质似乎在于胆碱能和γ-氨基丁酸能神经回路之间的关键平衡。
