Modulating the shift from goal-directed to habitual behaviors by manipulation of dopaminergic striatonigral loops

皮质-基底神经节回路（CBG）对于行为的学习和自动化至关重要。CBG是地形组织的，在学习过程中动态地相互作用，并分享多巴胺作为一种关键的神经递质。一个典型的假设是，奖赏和行为是由多巴胺能神经元连接的，多巴胺能神经元从奖赏介导的腹侧纹状体接收输入，并投射到行为介导的背侧纹状体。这种螺旋状纹状体-黑质-纹状体环的中心假设是合理的，并得到神经解剖学和行为学数据的支持。然而，迄今为止还没有在功能或分子水平上解决。在这里，我们建议结合联合收割机自动操作学习范式，光遗传学和单细胞RNA测序，探索这一假设在功能和分子水平上使用我们的高通量操作条件箱，我们将首先测量的动态目标导向收购和刺激反应为基础的习惯形成在野生型小鼠的线索奖励应急任务。 然后，我们将使用靶向的基于病毒的载体来光遗传学调节从腹侧被盖区（VTA）投射到背侧纹状体的多巴胺能神经元。然后，通过使用高成本效益的批量RNA-seq文库制剂分析来自相关脑区域的数百个样本，将行为评估的小鼠用于识别相关的分子变化和细胞身份。将使用来自相关区域的单细胞RNA-seq图谱和批量ATAC-seq图谱进行进一步表征。最后，我们建议将这些实验程序扩展到携带Foxp 2的人源化或非功能性等位基因的转基因小鼠，Foxp 2是一种与语音发育和语音进化相关的转录因子。由于Foxp 2人源化小鼠已被证明在CBG依赖性学习和自动化中受到影响，我们的研究将阐明CBG中多巴胺能回路的功能以及它们在人类语言进化和发展中的潜在作用。

Cortico-basal ganglia circuits (CBGs) are essential for the learning and automatization of behaviours. CBGs are topographically organized, interact dynamically during learning and share dopamine as a key neurotransmitter. A canonical hypothesis is that reward and behaviours are bridged by dopaminergic neurons that receive input from the reward-mediating ventral striatum and project to the behavior-mediating dorsal striatum. This central hypothesis of spiraling striatal-nigro-striatal loops is plausible and backed up by neuroanatomical and behavioral data. However, it has so far not been addressed at a functional or molecular level. Here, we propose to combine automated operant learning paradigms, optogenetics and single-cell RNA-sequencing to explore this hypothesis at a functional and molecular level.Using our high throughput operant conditioning chambers, we will first measure the dynamics of goal-directed acquisition and stimulus-response based habit formation in a cue-reward contingency task in wildtype mice. We will then use targeted virus-based vectors to optogenetically modulate dopaminergic neurons projecting from the ventral tegmental area (VTA) to the dorsal striatum. The behaviorally assessed mice will then be used to identify the associated molecular changes and cellular identities by analyzing hundreds of samples from relevant brain regions using highly cost-efficient bulk RNA-seq library preparations. Further characterization will be done using single-cell RNA-seq profiles and bulk ATAC-seq profiles from the relevant regions. Finally, we propose to extend these experimental procedures to genetically modified mice that carry humanized or non-functional alleles of Foxp2, a transcription factor associated with speech development and speech evolution. As mice humanized for Foxp2 have been shown to be affected in CBG-dependent learning and automatization, our study will shed light on the function of dopaminergic loops in CBGs as well as their potential role in the evolution and development of human speech.