A light at the end of the axon: genetically encoded fluorescent indicators shine light on the dopamine system

In this focused review, we center the attention on detection technologies used for monitoring dopamine (DA) release during animal behavior. We briefly examine the evolution of DA measurement techniques, from traditional methods like microdialysis and fast-scan cyclic voltammetry to cutting-edge genetically encoded fluorescent indicators (GEFIs). We then delve into how this latest generation technologies are contributing to unraveling some of the intricacies of the DA system, ranging from the spatial and molecular regulation of DA release, to the underlying rules governing its system-level functions. By showcasing recent exemplar works, we highlight how these modern tools provide new insights into the heterogeneity of DA signaling across different brain regions and help refining the theoretical framework of DA functions extending beyond the conventional reward prediction error model. Finally, we provide important methodological recommendations to be taken into consideration when employing DA GEFIs in neuroscience research.