In a study published in the journal Current Biology, a team of scientists, led by Zachary Mainen at the Champalimaud Centre for the Unknown (CCU), found a causal link between the activation of serotonin neurons and the amount of time mice are willing to wait, and rejected a possible link between increased serotonin neuron activation and reward.
Serotonin is a neuromodulatory chemical that is targeted by antidepressant drugs, such as Prozac, which are widely used to treat depression and other disorders such as chronic pain. Serotonin is normally released by a small set of cells in an area of the brain called the raphe nuclei. However, what naturally causes these neurons to become active and release serotonin and how this affects brain function are still poorly understood.