Dannenberg Holger, Pabst Milan, Braganza Oliver, Schoch Susanne, Niediek Johannes, Bayraktar Melike, Mormann Florian, Beck Heinz
Laboratory for Experimental Epileptology and Cognition Research, Department of Epileptology.
Section of Translational Epileptology, Institute for Neuropathology, and.
J Neurosci. 2015 Jun 3;35(22):8394-410. doi: 10.1523/JNEUROSCI.4460-14.2015.
The medial septum/diagonal band of Broca complex (MSDB) is a key structure that modulates hippocampal rhythmogenesis. Cholinergic neurons of the MSDB play a central role in generating and pacing theta-band oscillations in the hippocampal formation during exploration, novelty detection, and memory encoding. How precisely cholinergic neurons affect hippocampal network dynamics in vivo, however, has remained elusive. In this study, we show that stimulation of cholinergic MSDB neurons in urethane-anesthetized mice acts on hippocampal networks via two distinct pathways. A direct septo-hippocampal cholinergic projection causes increased firing of hippocampal inhibitory interneurons with concomitantly decreased firing of principal cells. In addition, cholinergic neurons recruit noncholinergic neurons within the MSDB. This indirect pathway is required for hippocampal theta synchronization. Activation of both pathways causes a reduction in pyramidal neuron firing and a more precise coupling to the theta oscillatory phase. These two anatomically and functionally distinct pathways are likely relevant for cholinergic control of encoding versus retrieval modes in the hippocampus.
内侧隔区/布罗卡斜角带复合体（MSDB）是调节海马节律发生的关键结构。在探索、新奇性检测和记忆编码过程中，MSDB的胆碱能神经元在海马结构中产生和调节θ波振荡方面发挥着核心作用。然而，胆碱能神经元如何精确地影响体内海马网络动力学，仍然不清楚。在本研究中，我们表明，在乌拉坦麻醉的小鼠中刺激胆碱能MSDB神经元通过两条不同的途径作用于海马网络。一条直接的隔区-海马胆碱能投射导致海马抑制性中间神经元的放电增加，同时主细胞的放电减少。此外，胆碱能神经元募集MSDB内的非胆碱能神经元。这条间接途径是海马θ同步所必需的。两条途径的激活都会导致锥体神经元放电减少，并与θ振荡相位更精确地耦合。这两条在解剖学和功能上不同的途径可能与海马中编码与检索模式的胆碱能控制有关。
