Dopamine receptors?

[deostroll]

How did we find out that inside our brain's limbic system there are dopamine receptors? But why are the receptors there? How do you evolutionarily account for it?

[stopherlogic]

Dopamine has functions in cognition and learning as well as other beneficial traits from an evolutionary point of view. Evolution would have favoured it and the emergence of a receptor for it I would think.