A 66-year-old retired professor develops difficulty naming objects and forming new memories while remote memories remain intact. MRI shows early hippocampal atrophy. Which aspect of hippocampal function is MOST specifically impaired in this clinical presentation?

• A Working memory maintenance
• B Long-term potentiation (LTP) required for encoding new explicit (declarative) memories, particularly episodic and semantic memories ✓
• C Procedural memory consolidation
• D Emotional conditioning via amygdala-hippocampal circuits

Explanation

The hippocampus is essential for encoding and consolidating new explicit (declarative) memories—episodic (personal experiences) and semantic (facts). This process depends on activity-dependent synaptic strengthening, specifically long-term potentiation (LTP) mediated by AMPA receptor insertion following NMDA receptor activation (Hebbian plasticity). Remote memories are relatively preserved because they have been transferred to neocortical storage over time (systems consolidation). Working memory is primarily a prefrontal function. Procedural memory (skills, habits) relies on the basal ganglia and cerebellum. Fear conditioning specifically involves the basolateral amygdala, though it interacts with hippocampal context encoding.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.