The basal ganglia are a chain of subcortical nuclei that facilitate action selection. Two striatal projection systems--so-called direct and indirect pathways--form the functional backbone of the basal ganglia circuit. Twenty years ago, investigators proposed that the striatum's ability to use dopamine (DA) rise and fall to control action selection was due to the segregation of D(1) and D(2) DA receptors in direct- and indirect-pathway spiny projection neurons. Although this hypothesis sparked a debate, the evidence that has accumulated since then clearly supports this model. Recent advances in the means of marking neural circuits with optical or molecular reporters have revealed a clear-cut dichotomy between these two cell types at the molecular, anatomical, and physiological levels. The contrast provided by these studies has provided new insights into how the striatum responds to fluctuations in DA signaling and how diseases that alter this signaling change striatal function.

中文翻译：

---

多巴胺对纹状体投射系统的调节。

基底神经节是一连串促进动作选择的皮质下核。两个纹状体投射系统——所谓的直接和间接通路——形成了基底神经节回路的功能骨干。二十年前，研究人员提出纹状体利用多巴胺 (DA) 上升和下降来控制动作选择的能力是由于直接和间接通路多刺投射神经元中 D(1) 和 D(2) DA 受体的分离. 尽管这个假设引发了一场争论，但从那时起积累的证据清楚地支持了这个模型。用光学或分子记者标记神经回路的手段的最新进展揭示了这两种细胞类型在分子、解剖和生理水平上的明确二分法。