Chapter 3: Neurobiology & Psychopharmacology

The chapter details how the brain maintains homeostasis and regulates crucial functions like mood, basic drives, memory, and the sleep cycle through specific areas, including the limbic system and hypothalamus. Neuronal activity is explored through electrical impulses and the release of neurotransmitters—chemical messengers such as dopamine, serotonin, norepinephrine, and GABA—which interact with receptors across the synapse. Disturbances in these pathways, such as excess dopamine in schizophrenia or deficiencies in serotonin/norepinephrine associated with depression, are presented as targets for treatment. Supporting the understanding of mental illness, the text reviews structural and functional brain imaging techniques like PET and MRI. The second major focus is pharmacotherapy, introducing core principles of pharmacodynamics (drug action on the body) and pharmacokinetics (drug movement—ADME). The influence of pharmacogenetics on individualized drug response due to variations in CYP enzymes is also addressed. The chapter comprehensively examines major psychotropic medication classes, explaining their mechanisms of action through receptor agonism, antagonism, or reuptake inhibition. These classes include antianxiety agents (benzodiazepines enhancing GABA), antidepressants (SSRIs, SNRIs, MAOIs), mood stabilizers (lithium, anticonvulsants), and antipsychotics (differentiating first- and second-generation effects and associated side effects like EPS and metabolic syndrome). Finally, medications for ADHD and Alzheimer's disease are covered, along with cautionary guidance regarding herbal treatments.