促觉醒肽orexins对内嗅皮层II层空间记忆相关的功能神经元时-空编码特性的影响及机制研究

Spatial learning and memory requires a good arousal state, which is primarily initiated and maintained by arousal-promoting systems including orexin peptide system. It has been found that the layer II of entorhinal cortex contains spatial information-related function cells (grid cells and border cells), and is closely related to the spatial cognition. Our previous study found that orexins regulate excitatory projection neurons in layer II of entorhinal cortex and contribute to spatial learning and memory. However, so far, the effects of orexins on the inhibitory interneurons, network oscillations and spatial information-related function cells in this layer of the entorhinal cortex remain elusive. Therefore, the present project will firstly explore the effects of orexins on interneuron excitability and the underlying neural mechanisms in the layer II of entorhinal cortex by patch-clamp recording and two-photon calcium imaging techniques. On this basis, we will use multiple-channels single-unit recording and optogenetic methods to investigate the influence of orexins on the network oscillations and spatial coding of functional neurons in the layer II of entorhinal cortex, with expectation to clarify the electrophysiological mechanisms underlying the effects of orexins on spatial learning and memory.

空间学习记忆依赖于良好的觉醒状态，而觉醒状态的维系依赖于orexins等促觉醒系统的调控。业已揭示，内嗅皮层II层神经网络中功能神经元（网格细胞及边界细胞）与空间认知高度相关。前期本项目组发现orexins能兴奋内嗅皮层II层谷氨酸能投射神经元，并参与空间学习记忆，而orexins对内嗅皮层II层神经网络中间神经元的影响，及网络振荡活动和空间编码特性的调控还不清楚。为此，本项目拟先采用膜片钳及双光子钙成像技术，探讨orexins对内嗅皮层II层中间神经元兴奋性的调控及机制。在完整地观测orexins对单个神经元调控的基础上，进一步采用多通道记录及光遗传学等技术，观察在空间探索过程中，orexins对内嗅皮层II层神经网络振荡活动及功能神经元空间编码特性的影响。以期在神经网络水平上，阐明orexins促觉醒系统关联空间学习记忆的神经电生理机制。

空间学习记忆依赖于良好的觉醒状态。觉醒不良，则空间认知功能自然下降。近来研究表明内嗅皮层II层在空间学习记忆中具有重要的作用。本项目从分子、细胞以及神经网络层次上，探讨了觉醒肽orexin对内嗅皮层II层的调控。采用顺行和逆行示踪技术，我们发现觉醒肽orexin神经元可直接投射至内嗅皮层II 层。觉醒肽orexin通过增强局部兴奋性神经元末梢的谷氨酸释放，进而兴奋内嗅皮层II层GABA能中间神经元。orexin觉醒肽对GABA能中间神经元的驱动作用可增加嗅皮层II层gamma网络振荡，进而促进了空间工作记忆的编码。为此，本项目研究结果不仅有望能为觉醒关联空间学习记忆提供新的理论证据，也为认知功能障碍疾病的诊治提供新的思路。