library_construction_protocol: Total 8 monkeys (4-15 years old, 8 males and 2 females, Macaca fascicularis) were used in the current project. All procedures complied with the NIH Guide for the Care and Use of Laboratory Animals approved by Sun Yat-sen University. Following 2 weeks of adaptive housing in the institutional animal facility, animals were anesthetized with a lethal dose of sodium pentobarbital. Animals were transcardially perfused with 2 liters of artificial cerebrospinal fluid (ACSF, in mM: 125 NaCl, 25 NaHCO3, 1 NaH2PO4, 2 KCl, 25 D-Glucose, 2 CaCl2, 1 MgCl2, 5 sodium l-ascorbate, 3 sodium pyruvate, 0.01 taurine, 2 thiourea, 1 kynurenic acid, 0.1 DL-AP5, and 1x10-3 tetrodotoxin). The flow of perfusion fluid was adjusted so that the perfusion finished within approximately 40 minutes. The brain was removed from the skull immediately and a block of tissue containing the hippocampus was cut off. The position of hippocampus referred to the atlas of the rhesus monkey brain (Saleem and Logothetis, 2012). The tissue block was kept in the ACSF and sectioned on a vibratome (VT1200S, Leica) in 300 um thick slices. The adherent tissues around the hippocampus of each slice were removed on ice and only the regions of interest were kept for dissociation. 10X single cell isolation protocol v2 10X Genomics Chromium platform v2