Which types of memories are most affected by hippocampal damage?

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Patient H.M. and short-term memory loss explained — hippocampus Learn about Henry Molaison (better known as “patient H.M.”), whose short-term memory loss following a lobotomy helped researchers to understand how brain structures are related to brain function.

Damage to the hippocampus primarily impairs the ability to form new declarative memories, which encompass facts and events. This condition is known as anterograde amnesia.1

Research, notably from the case of patient H.M., demonstrates that individuals with hippocampal dysfunction struggle to create new memories for specific experiences or information, even while other cognitive functions may remain largely intact. While there is ongoing scientific debate regarding the exact mechanisms, the hippocampus is considered essential for binding items and contexts into unified experiences and supporting conscious recollection.1

Additionally, some theories suggest the hippocampus remains critical for the long-term recall of episodic, context-rich memories. Because the hippocampus is also involved in spatial processing and navigation, damage to this region can further disrupt an individual's ability to map and navigate their environment.1