Scientists determine that dopmanine is released quickly in specific locations by specialized neurons. Also, seems like this is mediated by one specific protein (RIM).

https://hms.harvard.edu/news/zeroing-dopamine

Changliang Liu, Lauren Kershberg, Jiexin Wang, Shirin Schneeberger, Pascal S. Kaeser. Dopamine Secretion Is Mediated by Sparse Active Zone-like Release Sites. Cell, 2018; DOI: 10.1016/j.cell.2018.01.008