The Papez circuit, central to emotion and memory, involves which sequence of structures?

• A Hippocampus → fornix → mammillary bodies → anterior thalamic nuclei → cingulate gyrus → entorhinal cortex → hippocampus ✓
• B Amygdala → stria terminalis → hypothalamus → mediodorsal thalamus → prefrontal cortex → amygdala
• C Hippocampus → uncus → basal ganglia → centromedian thalamus → anterior cingulate → hippocampus
• D Mammillary bodies → ventral tegmental area → nucleus accumbens → prefrontal cortex → hippocampus

Explanation

The Papez circuit (1937) is the classical limbic memory-emotion loop: hippocampus → (via fornix) → mammillary bodies → (via mammillothalamic tract) → anterior nucleus of thalamus → cingulate gyrus → entorhinal/parahippocampal cortex → hippocampus. Lesions at any point can impair declarative memory consolidation (e.g., Korsakoff's psychosis from mammillary body damage). Option B describes the fear circuit involving the amygdala, which is a parallel but distinct loop.

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

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