Final answer:
Low levels of serotonin are associated with issues like anger, pessimism, and depression. Serotonin is targeted by antidepressants to help normalize its levels in the brain.
Step-by-step explanation:
The neurotransmitter serotonin is commonly associated with mood regulation, and low levels of serotonin are linked to symptoms such as anger, pessimism, and depression, especially in relation to personality disorder clusters B and C. Serotonin's role in mood disorders has been supported by various studies and is the target of many antidepressants, which work to normalize its levels in the brain. Other neurotransmitters such as dopamine, gamma aminobutyric acid (GABA), and glutamate also play pivotal roles in the central nervous system but are typically associated with different effects. For instance, GABA and glycine are primarily inhibitory, while glutamate is mainly excitatory, affecting postsynaptic cell depolarization.