中国科学院昆明动物研究所机构知识库

海马位于内侧颞叶，属于大脑皮层的边缘系统，是学习记忆的主要脑区。海马结构在空间上分为背侧和腹侧两部分，在亚区上可分为不同亚区，主要包括齿状回，海马角三，海马角二，海马角一，下托以及内嗅皮层。以往有关海马内部连接的研究主要集中在金典的三突触环路上，即内嗅皮层的第二和第三层细胞先投射到齿状回的颗粒细胞，齿状回的颗粒细胞再投射到苔藓纤维，苔藓纤维又投射到CA3，再由CA3投射到CA2和CA1，最后由CA1投射到下托，几乎忽略了海马双侧的连接及相关功能。硕士期间的主要研究内容为用病毒示踪技术解析背侧海马双侧连接的精细环路。首先用不跨突触的狂犬病毒证明双侧CA1，CA2，CA3和DG具有相互投射且双侧CA1和CA3的连接位于锥体细胞的基树突，双侧CA2的连接位于锥体细胞的顶树突；同时还证明背侧CA1双侧连接的神经纤维经过Dorsal hippocampal commissure和Ventral hippocampal commissure，但功能连接的神经纤维经过Dorsal hippocampal commissure；背侧CA2双侧连接的神经纤维经过Dorsal fornix。并且首次发现背侧CA2有到DG的直接投射。再组合使用跨一级突触的狂犬病毒和犬腺病毒证明双侧CA1形成recurrent 环路。硕士论文的另外一个内容是运动对老年鼠社交记忆的影响。社交记忆是由时间延迟而引起的老鼠对熟悉老鼠识别记忆减弱，社交识别记忆是老鼠从新颖同种个体中识别出熟悉老鼠的能力，当面对一个熟悉老鼠和一个新颖同种个体时，正常的老鼠会减少和熟悉老鼠的社交时间。社交记忆由识别同类的必要信息所组成，并且在许多社交行为中起重要的作用，比如患孤独症的小鼠就表现出明显的社交记忆障碍。我们首次发现与青年鼠相比老年鼠和转基因模型老年痴呆鼠的社交记忆受损。我们采用自愿转轮一个月的运动方式，一个月后检测老年鼠的社交记忆和海马区的突触可塑性。实验结果显示：经过一个月的转轮运动后，转轮老年鼠和转基因模型老年痴呆鼠的社交记忆较不转轮和青年鼠的有所提高；转轮老年鼠和转基因模型老年痴呆鼠海马齿状回颗粒下层区的突触可塑性增强。所以我们得出结论：运动能通过增加老年鼠和转基因模型老年痴呆鼠海马突触可塑性来改善老年鼠和转基因模型老年痴呆鼠的社交记忆。综上，在硕士阶段我主要用病毒示踪技术解析了背侧海马双侧连接的精细环路以及运动能通过增加老年鼠和转基因模型老年痴呆鼠海马突触可塑性来改善老年鼠和转基因模型老年痴呆鼠的社交记忆。 

Hippocampus locates in the medial temporal lobe, which belongs to the limbic system of the cerebral cortex, is the main area of learning and memory. Hippocampal formation can be divided into the ventral and dorsal part in space, and it also can be divided into different subregions, mainly includes dentate gyrus, Cornu ammonis 1, Cornu ammonis 2, Cornu ammonis 3, subiculum and entorhinal cortex. Previous studies of hippocampal internal connections are mainly concentrated in the classic trisynaptic circuits: the second and third layer of cells in entorhinal cortex project to the dentate gyrus granular cells, then the dentate gyrus granular cells project to CA3, CA3 project to CA2 and CA1, lastly CA1 project to subiculum. Wheres just a few studies pay attention to the bilateral hippocampus connections and let alone it’s functions.My main research is dissect the bilateral dorsal hippocampus connections by using the virual tracing technique. Firstly, I proved that the bilateral dorsal CA1, CA2, CA3 and DG have strong connections; the ipsilateral CA1, CA3 receive projections at stratum oriens from contralateral CA1, CA3 respectively; the ipsilateral CA2 receive projections at stratum radiatum from contralateral CA2; the dorsal CA1 project through dorsal hippocampal commissure and ventral hippocampal commissure to form the bilateral connections and the dorsal CA2 project through dorsal fornix to form the bilateral connections by using the non-transynaptic rabbies virus. And I am the first one discovered that CA2 can project back to DG. Lastly, I found that the bilateral dorsal CA1 formed a recurrent circuit by combinational using of the monosynaptic rabbies and CAV-cre virues.During my master study, another research topic is the effect of exercise on aged mice. Social memory is Time?delayed recognition of a familiar mouse. social recognition is the ability to distinguish familiar from novel conspecifics. Social recognition by a subject mouse is defined by reduced social approach or reduced time spent investigating a familiar partner and reinstatement of investigation when a novel partner is introduced. Social memory consists of the information necessary to identify and recognize cospecifics and is essential to many forms of social interaction, such as autism showed obvious social memory impairment in mice.Firstly, we found that the aged and AD mice social memory are impaired comparing to the wild type young mice. Secondly, we adopt voluntary wheel running to prove if the aged and AD mice social memory can be improved. Experimental results show that after a month of wheel running, the aged and AD mice social memory are improved and the synaptic plasticity of the aged and AD mice in the hippocampal dentate gyrus is enhanced. So we got the conclusion that exercise can improve aged and AD mice social memory by increasing hippocampal synaptic plasticity.As discussied in above, I dissected the bilateral dorsal hippocampus connections by using the virual tracing technique and proved that that exercise can improve aged and AD mice social memory by increasing hippocampal synaptic plasticity.during my master study.