A 1" hard enamel yin yang pin with screenprinted dopamine molecules. 

This pin was created in collaboration with Dr. Han de Jong of the Lammel Lab at UC Berkeley to communicate the yin and yang of dopamine. For a long time, people thought dopamine was the "pleasure molecule", but the story is much more complicated. Dopamine also signals aversion, not just reward! To learn more about the brain circuits in which dopamine signals reward and aversion, check out Han's paper!