Hippocampus

What is the Hippocampus?

The hippocampus is a curved brain structure in the medial temporal lobe, with one on each side of the brain. It is important for forming memories of events and experiences and for representing spatial information.

Structure and function

The hippocampus proper contains the CA fields. The broader hippocampal formation also includes the dentate gyrus and subiculum. These interconnected regions participate in learning and memory.

The hippocampus is a major site for research on long-term potentiation (LTP), a lasting increase in the strength of connections between neurons. LTP provides a mechanism through which activity can change neural communication; it is not confined to the hippocampus or a complete explanation of memory.

Place cells in the hippocampus respond in relation to particular locations, helping represent where an animal is in its environment. This is one reason the hippocampus is central to research on spatial navigation.

Hippocampal damage and memory

Damage can make it difficult to form new memories, including anterograde amnesia: impaired formation of memories after the injury or disease begins. The exact difficulties depend on the extent and location of damage. The hippocampus is also affected in Alzheimer's disease.

Stress, exercise, and neurogenesis

The hippocampus is sensitive to stress-related processes. Chronic stress has been linked to changes in its structure and function, but a brain-volume measurement alone does not explain a person's memory difficulties.

Neurogenesis is the formation of new neurons. Exercise- and enrichment-related increases in hippocampal neurogenesis are best established in animals. Human research is more difficult: an increase in MRI-measured volume is not a count of newborn neurons.

A 2011 randomized exercise study measured hippocampal volume and spatial memory in older adults. A 2026 study of human hippocampal neurogenesis examined neurogenic cell profiles in post-mortem tissue across ageing and cognitive-status groups. These approaches answer different questions. The contribution of newly formed neurons to adult human cognition remains under investigation.