CARN Neurobiology of Addiction 2 — Questions and Answers
Question 1: Which neurotransmitter is primarily responsible for the reinforcing effects of addictive substances in the mesolimbic pathway?
- Serotonin
- Dopamine (Correct answer)
- GABA
- Norepinephrine
Correct answer: Dopamine
Dopamine release in the nucleus accumbens via the mesolimbic pathway mediates the rewarding and reinforcing effects of addictive substances.
Question 2: The ventral tegmental area (VTA) sends dopaminergic projections to which structure most critically involved in drug reward?
- Amygdala
- Hippocampus
- Nucleus accumbens (Correct answer)
- Prefrontal cortex
Correct answer: Nucleus accumbens
The VTA projects dopaminergic neurons to the nucleus accumbens (NAc), forming the mesolimbic pathway central to reward and addiction.
Question 3: Neuroadaptation to chronic opioid use leads to upregulation of which intracellular signaling pathway, contributing to tolerance?
- PKA/cAMP pathway (Correct answer)
- mTOR pathway
- JAK-STAT pathway
- PI3K/Akt pathway
Correct answer: PKA/cAMP pathway
Chronic opioid exposure causes upregulation of the adenylyl cyclase/cAMP/PKA pathway (cAMP superactivation), which underlies tolerance and withdrawal symptoms.
Question 4: Which brain region is most associated with drug-cue conditioned responses and craving triggered by environmental stimuli?
- Cerebellum
- Basal ganglia
- Amygdala (Correct answer)
- Thalamus
Correct answer: Amygdala
The amygdala encodes emotional memories associated with drug use and mediates conditioned responses to drug-related cues that trigger craving.
Question 5: Delta FosB accumulation in the nucleus accumbens after repeated drug exposure is significant because it:
- Causes immediate sedation
- Acts as a long-lasting transcription factor increasing addiction vulnerability (Correct answer)
- Blocks dopamine synthesis
- Reverses neuroplasticity changes
Correct answer: Acts as a long-lasting transcription factor increasing addiction vulnerability
Delta FosB is a stable transcription factor that accumulates with repeated drug exposure and persistently alters gene expression, increasing addiction vulnerability.
Question 6: The endogenous opioid system's role in addiction is best described as:
- Primarily regulating cardiovascular responses to drugs
- Modulating pain, reward, and stress responses through mu, kappa, and delta receptors (Correct answer)
- Exclusively mediating anxiolytic effects
- Controlling only withdrawal symptoms without affecting reward
Correct answer: Modulating pain, reward, and stress responses through mu, kappa, and delta receptors
Endogenous opioids (endorphins, enkephalins, dynorphins) act on mu, kappa, and delta receptors to modulate pain, reward, and stress — all critical components of addiction.
Question 7: Allostasis in addiction refers to:
- The brain's return to its pre-addiction baseline after abstinence
- Maintaining stability through change, often resulting in a new, dysregulated set point (Correct answer)
- The acute euphoric response to drug administration
- Synaptic pruning caused by chronic substance use
Correct answer: Maintaining stability through change, often resulting in a new, dysregulated set point
Allostasis involves achieving stability through adaptive changes; in addiction, this creates a dysregulated emotional set point requiring drug use to feel 'normal.'
CARN Neurobiology of Addiction 2
Which neurotransmitter is primarily responsible for the reinforcing effects of addictive substances in the mesolimbic pathway?