Dr. Kent Berridge, a professor of psychology and neuroscience at the University of Michigan, is a pioneering figure in the process of disentangling dopamine desire circuits from here-and-now liking circuits. He found that when a rat tastes a sugar solution, it signals liking by licking its lips. In contrast, it expresses wanting by consuming more of the sweet liquid. When he injected a chemical into a rat’s brain that boosted dopamine, it consumed more sugar water, but
