Hippocampectomy: Consequences for Memory, Navigation, and Emotion

Surgical removal of the hippocampus (hippocampectomy) produces profound, selective cognitive deficits:

• Anterograde amnesia: Inability to form new explicit (declarative) memories; pre-surgery memories largely intact.
• Spatial navigation impairment: Loss of cognitive mapping, route learning, and orientation.
• Episodic memory disruption: Difficulty recalling personal events with spatiotemporal context.
• Preserved procedural memory: Motor skills, habits, and conditioning remain intact (basal ganglia/cerebellum dependent).
• Emotional blunting: Reduced affect and impaired fear conditioning due to amygdala disconnection.
• Contextual learning deficits: Inability to bind information to its learning context.
• Impaired consolidation: Hippocampus normally transfers memories to neocortical long-term storage; without it, consolidation fails.

Outcomes vary; some compensation by adjacent cortical areas may occur. The procedure is now rare, reserved for intractable epilepsy, but its study fundamentally shaped modern memory neuroscience.