The invention provides a chemical entity of Formula (I): , wherein R1, R2, X, Y and Z have any of the values described herein, and compositions comprising such chemical entities； methods of making them； and their use in a wide range of methods as disclosed herein, including metabolic and reaction kinetic studies； detection and imaging techniques； radioactive treatments； modulating and treating disorders mediated by PDE2 activity； treating neurological disorders, CNS disorders, dementia, neurodegenerative diseases, and trauma-dependent losses of function； treating stroke, including cognitive and motor deficits during stroke rehabilitation； facilitating neuroprotection and neurorecovery； enhancing the efficiency of cognitive and motor training, including animal skill training protocols； and treating peripheral disorders, including hematological, cardiovascular, gastroenterological, and dermatological disorders.本發明提供式(I)之化學實體：，其中R1、R2、X、Y及Z具有本文所述任何值，及包含該等化學實體之組合物；其製備方法；及其在廣泛範圍如本文所揭示之方法中之用途，包括代謝及反應動力研究；檢測及成像技術；放射性治療；調節及治療由PDE2活性介導之病症；治療神經病症、CNS病症、失智症、神經退化疾病及創傷依賴性功能喪失；治療中風，包括中風復健期間之認知及運動缺陷；促進神經保護及神經復原；增強認知及運動訓練之效率，包括動物技能訓練方案；及治療周圍病症，包括血液、心血管、胃腸病及皮膚病。
