ADM Neurobiology of Addiction 1 — Questions and Answers
Question 1: Which neurotransmitter system is primarily responsible for the rewarding effects of most addictive substances?
- Serotonergic system
- Dopaminergic system (Correct answer)
- Cholinergic system
- Histaminergic system
Correct answer: Dopaminergic system
The dopaminergic system, particularly the mesolimbic pathway, mediates reward and reinforcement central to the addictive properties of most substances.
Question 2: The mesolimbic dopamine pathway originates from which brain region?
- Locus coeruleus
- Raphe nuclei
- Ventral tegmental area (Correct answer)
- Substantia nigra pars compacta
Correct answer: Ventral tegmental area
The mesolimbic pathway originates in the ventral tegmental area (VTA) and projects to the nucleus accumbens, amygdala, and prefrontal cortex.
Question 3: Long-term substance use causes downregulation of dopamine D2 receptors, contributing primarily to which phenomenon?
- Sensitization
- Tolerance and anhedonia (Correct answer)
- Hyperalgesia
- Kindling
Correct answer: Tolerance and anhedonia
Chronic dopamine surges cause receptor downregulation, reducing the brain's response to natural rewards and producing tolerance and anhedonia characteristic of addiction.
Question 4: Which brain structure is most implicated in conditioned cue-induced drug craving?
- Hippocampus
- Cerebellum
- Amygdala (Correct answer)
- Thalamus
Correct answer: Amygdala
The amygdala encodes emotional memories associated with drug use; re-exposure to conditioned cues activates the amygdala, driving intense cravings.
Question 5: Dysfunction of the prefrontal cortex in addiction primarily impairs which capacity?
- Sensory perception
- Inhibitory control and decision-making (Correct answer)
- Motor coordination
- Declarative memory formation
Correct answer: Inhibitory control and decision-making
The prefrontal cortex governs executive function; its hypofunctionality in addiction impairs inhibitory control, contributing to compulsive drug-seeking despite negative consequences.
Question 6: Opioid-induced euphoria and analgesia are primarily mediated by agonism at which receptor type?
- NMDA receptors
- Mu-opioid receptors (Correct answer)
- Kappa-opioid receptors
- GABA-B receptors
Correct answer: Mu-opioid receptors
Mu-opioid receptors (MOR) are the primary mediators of opioid-induced euphoria, analgesia, and respiratory depression, and are central to opioid use disorder pathophysiology.
Question 7: Neurobiological tolerance to opioids is primarily driven by which cellular mechanism?
- Receptor upregulation and sensitization
- Receptor desensitization and internalization (Correct answer)
- Increased neurotransmitter synthesis
- Enhanced blood-brain barrier permeability
Correct answer: Receptor desensitization and internalization
Repeated opioid exposure causes mu-opioid receptor desensitization (uncoupling from G-proteins) and internalization, reducing cellular response to the same dose.
ADM Neurobiology of Addiction 1
Which neurotransmitter system is primarily responsible for the rewarding effects of most addictive substances?