What is the Hippocampus?

By Dr. Ananya Mandal, MDReviewed by Sally Robertson, B.Sc.

The hippocampus is a small region of the brain that forms part of the limbic system and is primarily associated with memory and spatial navigation.

Anatomy and location

The hippocampus is located in the medial temporal lobe of the brain, underneath the cortical surface. Its structure is divided into two halves which lie in the left and right sides of the brain. The organ is curved with a shape that resembles a seahorse, and its name is derived from a coupling of the Greek words "hippo" for horse and "kampos" for sea.

History and discovery

The hippocampus was first referred to by Venetian anatomist Julius Caesar Aranzi in 1587. He described it as a ridge along the floor of the temporal horn of the lateral ventricle and likened it first to a silkworm and later, to a seahorse. In the 1740s, a Parisian surgeon René-Jacques Croissant de Garengeot coined the term "cornu Ammonis," meaning the horn of Amun, an ancient Egyptian god.

Functions and disorders of the hippocampus

The hippocampus deals with the formation of long-term memories and spatial navigation. In diseases such as Alzheimer's disease, the hippocampus is one of the first regions of the brain to become damaged and this leads to the memory loss and disorientation associated with the condition.

The hippocampus can become also become damaged through oxygen deprivation or hypoxia, infection or inflammation or as a result of temporal lobe epilepsy. Individuals with hippocampal damage develop amnesia and may be unable to form new memories of the time or location of an event, for example.

Further Reading

• All Hippocampus Content
• Hippocampus Functions
• Hippocampus Physiology
• Hippocampus Evolution