Sun Dechuan, Unnithan Ranjith Rajasekharan, French Chris
Department of Medicine, The University of Melbourne, Melbourne, VIC, Australia.
Department of Electrical and Electronic Engineering, The University of Melbourne, Melbourne, VIC, Australia.
Front Neurosci. 2021 Mar 19;15:640350. doi: 10.3389/fnins.2021.640350. eCollection 2021.
The hippocampus and associated cholinergic inputs have important roles in spatial memory in rodents. Muscarinic acetylcholine receptors (mAChRs) are involved in the communication of cholinergic signals and regulate spatial memory. They have been found to impact the memory encoding process, but the effect on memory retrieval is controversial. Previous studies report that scopolamine (a non-selective antagonist of mAChR) induces cognitive deficits on animals, resulting in impaired memory encoding, but the effect on memory retrieval is less certain. We tested the effects of blocking mAChRs on hippocampal network activity and neural ensembles that had previously encoded spatial information. The activity of hundreds of neurons in mouse hippocampal CA1 was recorded using calcium imaging with a miniaturised fluorescent microscope and properties of place cells and neuronal ensemble behaviour in a linear track environment were observed. We found that the decoding accuracy and the stability of spatial representation revealed by hippocampal neural ensemble were significantly reduced after the administration of scopolamine. Several other parameters, including neural firing rate, total number of active neurons, place cell number and spatial information content were affected. Similar results were also observed in a simulated hippocampal network model. This study enhances the understanding of the function of mAChRs on spatial memory impairment.
海马体及相关胆碱能输入在啮齿动物的空间记忆中起着重要作用。毒蕈碱型乙酰胆碱受体（mAChRs）参与胆碱能信号的传递并调节空间记忆。已发现它们会影响记忆编码过程，但对记忆提取的影响存在争议。先前的研究报告称，东莨菪碱（一种mAChR的非选择性拮抗剂）会导致动物出现认知缺陷，从而损害记忆编码，但对记忆提取的影响尚不确定。我们测试了阻断mAChRs对海马体网络活动以及先前编码空间信息的神经集合的影响。使用小型荧光显微镜通过钙成像记录了小鼠海马体CA1中数百个神经元的活动，并观察了线性轨道环境中位置细胞的特性和神经集合行为。我们发现，给予东莨菪碱后，海马体神经集合所揭示的解码准确性和空间表征的稳定性显著降低。其他几个参数，包括神经放电率、活跃神经元总数、位置细胞数量和空间信息含量也受到了影响。在模拟海马体网络模型中也观察到了类似结果。这项研究增进了对mAChRs在空间记忆损伤中功能的理解。
