How many hippocampi does the human brain have?

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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.

The human brain has two hippocampi, one located in each of the left and right temporal lobes.1

The hippocampus is a critical region of the brain primarily associated with memory and spatial navigation. Because it is a paired structure, damage to both sides can lead to significant cognitive deficits, such as the inability to form new declarative memories, as famously observed in the case of patient H.M.1