Dopamine release in the reward circuitry increases during pleasurable or reinforcing activities.

“you might think of the brain as a collection of wires uh those wires are neurons they send electrical impulses one to the other but the neurons don't actually touch end to end there's a little gap between them called the synap gaps and that Gap is bridged by molecules called neurotransmitters there are many different neurotransmitters in the brain um they have many different functions but dopamine has become uh kind of the common currency for measuring pleasure reward and motivation it's not the only neurotransmitter involved in that process obviously but it is the final common pathway for all reinforcing substances and behaviors”