Which failure mode becomes likely when dopamine D2 receptor density decreases in the nucleus accumbens of a cocaine user?

💡 Explanation

Addiction causes a downregulation of D2 receptors. Because fewer receptors are available, the reward circuit is less sensitive, leading to an increased craving to achieve the same effect; therefore, relapse becomes more likely, rather than reduced cravings or increased aversion.

• An engineer studying cognitive function during sleep monitors a subject whose adenosine receptors are experimentally blocked. Which outcome is most likely regarding the subject's sleep architecture?
• Why does accommodation lag during rapid shifts from far to near objects in individuals with presbyopia?
• A 60-year-old experiences blurred near vision despite clear distance sight. What distinguishes this age-related presbyopia from simple myopia?
• A patient's heart exhibits chronically elevated end-systolic volume. Which mechanism explains why this increased volume diminishes overall cardiac efficiency?
• If a drug's clearance is significantly reduced due to impaired renal function in a patient with chronic kidney disease, which consequence is most likely?
• Which process impedes neuronal signal transmission when gap junctions narrow?