Pedemonte M, Barrenechea C, Nuñez A, Gambini J P, García-Austt E
Neurofisiología, Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Av. Gral. Flores 2125, 11800 Montevideo, Uruguay.
Brain Res. 1998 Jul 27;800(1):145-53. doi: 10.1016/s0006-8993(98)00517-4.
The lateral septum receives the most important afferents from the hippocampus, has been proposed to contribute to theta (theta) rhythm generation. Our aim was to study the membrane and circuital properties of lateral septum neurons and their relationship with hippocampal rhythms. Extra- and intracellular recordings (n=81) were obtained in urethane-anesthetized rats. Two neuronal populations were found, one of them with hippocampal theta; rhythm dependence (theta-D, 68%), and the other group independent of hippocampal theta; rhythm (theta-I, 32%). Other differences were spontaneous firing rate (theta-D=13.20+/-2.09, theta-I=6.99+/-1.18; p<0.005) with a bursting pattern in the theta-D group and single discharges in the theta-I group. Intracellular recordings showed higher synaptic activity in theta-D than in theta-I neurons. Both groups showed fast spikes while only theta-D neurons had high-threshold and low-threshold slow spikes. theta-D neurons had theta-oscillations in their membrane potential. Stimulation of the contralateral lateral septum resets the hippocampal theta rhythm and the theta rhythm recorded intracellularly in the lateral septum neurons. Some neurons (10.6%) showed rhythmic oscillations lasting a few seconds, at a higher frequency than those of the simultaneously recorded hippocampal EEG. This high frequency appeared spontaneously or could be evoked by stimulations of the fornix and reticularis pontis oralis nucleus (RPO). Homologous high frequency oscillations appeared in the simultaneously recorded hippocampal EEG, synchronized with the neuronal activity, during fornix stimulation. RPO stimulation evoked increments (57%) or decrements (43%) in the firing rate of lateral septum neurons. Thus, they could participate in different septal networks to modulate the theta rhythm. The marked functional relationship between lateral septum neurons and hippocampal theta rhythm supports the proposal that lateral septum represents a feedback system for the improvement of medial septum theta rhythm. The hypothalamic projections could be a way to introduce theta and higher rhythms into this structure that control many biological rhythms.
外侧隔区接收来自海马体的最重要传入信号，有人提出它有助于θ节律的产生。我们的目的是研究外侧隔区神经元的膜特性和电路特性及其与海马体节律的关系。在氨基甲酸乙酯麻醉的大鼠中进行了细胞外和细胞内记录（n = 81）。发现了两类神经元群体，其中一类与海马体θ节律相关（θ-D，68%），另一组与海马体θ节律无关（θ-I，32%）。其他差异包括自发放电率（θ-D = 13.20±2.09，θ-I = 6.99±1.18；p < 0.005），θ-D组呈爆发模式，θ-I组为单个放电。细胞内记录显示，θ-D神经元的突触活动高于θ-I神经元。两组均显示快速尖峰，而只有θ-D神经元具有高阈值和低阈值慢尖峰。θ-D神经元的膜电位存在θ振荡。刺激对侧外侧隔区可重置海马体θ节律以及外侧隔区神经元细胞内记录到的θ节律。一些神经元（10.6%）表现出持续数秒的节律性振荡，频率高于同时记录的海马体脑电图。这种高频振荡可自发出现，或可由穹窿和脑桥嘴侧网状核（RPO）的刺激诱发。在穹窿刺激期间，同时记录的海马体脑电图中出现同源高频振荡，并与神经元活动同步。RPO刺激可使外侧隔区神经元的放电率增加（57%）或减少（43%）。因此，它们可能参与不同隔区网络来调节θ节律。外侧隔区神经元与海马体θ节律之间显著的功能关系支持了外侧隔区代表一个用于改善内侧隔区θ节律的反馈系统的观点。下丘脑投射可能是将θ节律和更高节律引入该结构以控制许多生物节律的一种方式。
