serotonin
Star Trek: The Next Generation
Episode: TNG 206 - Game, The
Biochemical substance that, among other unknown effects, acts as a central neurotransmitter in humanoid nervous systems, making them susceptible to influence. On stardate 45208.2, the addictive Ktaran game initiated a serotonin cascade in the frontal lobe of the brain, purposefully designed to control those who played the "game."
