The hippocampus, a small, curved structure located deep within the brain’s temporal lobe, plays a complex role in various neural processes. Resembling a seahorse, this bilateral structure is part of the limbic system, a network of brain regions involved in emotion, motivation, and memory. Its internal organization allows it to process and relay information across different neural pathways.
The Brain’s Memory Hub
The hippocampus is known for forming new long-term memories, particularly declarative memories. It acts as a temporary processing center, consolidating information from short-term memory before it is stored in other cortical areas for long-term retention. This function was illustrated by the case of Patient H.M. (Henry Molaison), who, after surgery to remove portions of his hippocampus, became unable to form new explicit memories. Despite this, H.M. retained older memories and could learn new motor skills, demonstrating the hippocampus’s specific role in declarative memory formation rather than long-term storage or procedural memory.
Beyond Memory: Navigation and Emotion
While memory is a primary function, the hippocampus also contributes to other cognitive and emotional processes. It is involved in spatial navigation, helping individuals understand and remember their location and surroundings. This function enables us to navigate familiar spaces without becoming disoriented.
The hippocampus also connects with emotional regulation, particularly in processing fear and anxiety responses. It works closely with the amygdala, the brain’s “fear center,” to link memories with emotional contexts. This connection explains why returning to a location where an emotional event occurred can sometimes trigger those same emotions.
Its Role in Brain Health and Disease
Dysfunction or damage to the hippocampus is associated with various neurological and psychiatric conditions. In Alzheimer’s disease, the hippocampus is one of the first brain regions to show atrophy and tissue loss, contributing to memory impairments seen in early stages of the disease. The hippocampus is also a common site for seizure origins in temporal lobe epilepsy, where abnormal electrical activity can lead to symptoms like emotional changes and memory loss. Furthermore, conditions like Post-Traumatic Stress Disorder (PTSD) and depression often show changes in hippocampal volume or activity. Individuals with PTSD may have reduced hippocampal volume, and chronic stress can negatively impact its function, affecting memory and emotional regulation.