The release and reuptake of neurotransmitters (serotonin, norepinephrine, and dopamine) in the brain is linked to a person’s mood. Depression has been linked to the imbalance of these neurotransmitters (NTs), but unfortunately this is hard to prove, as it is very difficult to measure the concentrations of these NTs in the brain. What is known, is that antidepressants act on these NTs as well as their receptors.