Post-mortem studies of people who have committed suicide have found consistent evidence for a hypoactive _____ system.

A) serotonin
B) dopamine
C) norepinephrine
D) melatonin
E) epinephrine

Hypoactive

Displaying lower than normal activity or responsiveness.

Serotonin

A neurotransmitter that plays a key role in mood regulation, sleep, digestion, and other bodily functions.

Dopamine

A neurotransmitter in the brain that plays a major role in reward-motivated behavior and is involved in many functions, including motivation, arousal, and motor control.