Questions: Drug Classes and Their Effects on Behavior
2 questions to test your understanding
Score: 0 / 2
Question 1 Short Answer
Cocaine and morphine are chemically very different, yet both produce euphoria and addiction. What is the common mechanism?
Think about your answer, then reveal below.
Model answer: Both ultimately increase dopamine signaling in the mesolimbic pathway (nucleus accumbens). Cocaine does so directly by blocking dopamine reuptake; morphine does so indirectly by suppressing GABAergic interneurons in the VTA, disinhibiting dopamine neurons.
The mesolimbic dopamine pathway is the common reward substrate for most addictive drugs. Understanding this convergence explains why addiction has similar behavioral features (craving, tolerance, withdrawal) across diverse substances, and why treatments targeting dopamine signaling can have broad applicability.
Question 2 Short Answer
A patient is prescribed a benzodiazepine for anxiety. What neurotransmitter system does it primarily affect, and what is the key risk of long-term use?
Think about your answer, then reveal below.
Model answer: Benzodiazepines enhance GABA-A receptor function, increasing inhibitory tone. Long-term use produces tolerance (receptor downregulation) and physical dependence; abrupt withdrawal causes rebound hyperexcitability that can manifest as seizures.
Because GABA-A receptors are broadly distributed, benzodiazepine effects (and withdrawal) are systemic. The tolerance mechanism — receptor downregulation — is the same process that underlies tolerance to all depressants, including alcohol.