Where drugs act: the brain's regions

Gives you the geography: which region controls breathing, movement, reward and mood — so a drug's effects map to places.

Where this fitsConnects to 2 · Unlocks 2

Connects to: Dopamine: receptor families, clearance and pathways — Dopamine pathways run between these regions (VTA → nucleus accumbens, substantia nigra → striatum).
Primary effects and side effects — Side effects often come from the same target in a different region.
Unlocks: The neuron and the action potential — Zoom from regions into the cells that make them up.
Dopamine: receptor families, clearance and pathways — You'll need the VTA, nucleus accumbens and substantia nigra for dopamine pathways.

Orient

Peripheral nervous system (PNS) – nerves that project from spinal cord to rest of body, and nerves within organs. Central nervous system (CNS) – brain and spinal cord. For psychoactive drugs, primary effects are due to CNS action; sometimes side effects are due to PNS activity. The brain divides into hindbrain, midbrain and forebrain (diencephalon and telencephalon).

Course terms

Your professor's wording, word for word from the slides. Learn the term and this definition — the explanation underneath is only there to help it make sense.

Peripheral nervous system (PNS): “Nerves that project from spinal cord to rest of body”Slides 02, p. 2
Also nerves within organs. Some side effects of psychoactive drugs come from here.
Central nervous system (CNS): “Brain and spinal cord”Slides 02, p. 2
Where psychoactive drugs have their primary effects.
Brain stem (pons, medulla): “Brain stem - controls crucial bodily functions”Slides 02, p. 4
Respiration, heart rate/blood pressure, digestion, sleep/wakefulness. Inhibited respiration is the major fatal overdose risk (opioids vs. cannabis).
Cerebellum: “Inhibition of cerebellum results in ataxia (as seen in alcohol use)”Slides 02, p. 4
The cerebellum handles balance, coordination, movement and posture integration; ataxia = loss of coordination.
Ventral tegmental area (VTA): “Connects to limbic system, role in reward and motivation (and therefore drug seeking behaviors)”Slides 02, p. 5
Midbrain tegmentum, next to the substantia nigra.
Thalamus: “Sensory “relay station””Slides 02, p. 6
Important role in perception and sensory attention.
Hypothalamus: “Eating, drinking, sleeping, temperature control (homeostasis)”Slides 02, p. 6
Also controls hormone release in pituitary and pineal glands, sexual behavior and sleep regulation.
Basal ganglia / striatum: “Damaged in Parkinson’s disorder”Slides 02, p. 7
Striatum = caudate nucleus + putamen; receives connections from substantia nigra; large role in movement.
Nucleus accumbens (NAc): “Reward circuit”Slides 02, p. 8
Limbic system; receives connections from VTA.
Amygdala and hippocampus: “Contributes to regulation of mood, affect, emotion, responses to emotional experiences”Slides 02, p. 8
Also learning and memory.

From your course: Course slides 02, pp. 2–9

Tip: the ← and → keys move through the lesson.

Full lesson: CNS/PNS and brain regions