中国科学院心理健康重点实验室知识库

目的 “躺平”作为现代流行词汇，描述部分人群的心理状态，但其心理学含义仍未明确。一定条件下的动机缺乏可能是关键心理特征之一。方法 将16只雄性SD大鼠随机分配到两种限食水平(分别为基线体重的90%和80%),并进行蔗糖颗粒自我给药任务，尝试建立“躺平”的动机缺乏动物行为模型，模型的建立分为3个阶段，第一阶段学习鼻触一次高回报侧获得一粒糖丸，第二阶段学习多次鼻触低回报侧获得一颗糖丸，第三阶段观察大鼠在高回报侧可以获得不同程度奖励的情况下，还是否愿意多付出努力在低回报侧获得糖丸。结果 结合自给食训练和免疫印迹，结果显示：(1)大鼠在第三阶段出现“躺平”现象，即在高回报侧获得最大奖励的90%及以上，且低回报侧努力程度增大到断点时，大鼠放弃努力获得更多糖丸奖励。(2)与“未躺平”组的大鼠相比，“躺平”组大鼠伏隔核内的多巴胺D1受体表达显著升高，而D2受体表达没有显著差异。结论 大鼠可表现出“躺平”样行为，伏隔核中D1受体表达上调可能是“躺平”动机缺乏的重要分子基础，该模型的建立扩展了对“躺平”的理解，并为其机制研究提供了新范式。

Objective "Lie flat" has recently become a buzz word describing a specific psychological state in some individuals. However, its psychological meaning and mechanisms remain unclear. Lack of motivation under certain conditions may be one of the key psychological characteristics of this condition. Methods Sixteen male SD rats were randomly assigned to two food-restriction levels(90% and 80% of baseline weight, respectively)，and subjected to a sucrose-pellet self-administration task. The establishment of the model is divided into three stages. The rats were trained to self-administer sucrose pellets in a high-reward learning stage and in a low-reward learning stage. We then assessed "lie flat" behavior in a preference-test stage，in which rats could choose between high-reward- and low-reward-paired nose-pokes in a discrete choice procedure. Results Combining self-feeding training with Western blot, the results showed that： (1) rats showed significantly decreased nose-poke behavior for low-reward，i. e.“lie flat" behavior but not for high-reward，when ≥90% of the maximal reward was obtained in the high-reward task and the effort(X) in the low-reward task increased to the breaking point.(2) Dopamine D1R expression in the NAc was significantly higher in the "lie flat" group compared with the "not lie flat" rats，while D2R expression was similar in both groups. Conclusions Rats can show "lie flat" behavior，and up-regulation of D 1 R expression in the NAc may be a key part of the molecular basis responsible for this motivation deficiency in“lie flat" behavior. These results extend our understanding of "lie flat" behavior, and provide a new paradigm for the study of its mechanism.

山西省基础研究计划资助项目（202303021221159）;; 山西省高等学校青年学术带头人项目（2024Q028）;; 山西中医药大学优秀博士毕业生来晋工作奖励经费科研启动基金项目（2023BKS07）;; 首都师范大学横向课题基金项目（KJ20210110）;; 中国科学院心理健康重点实验室开放课题（KLMH2020K06）