The hippocampus is a seahorse shaped structure deep in the temporal lobe that plays a central role in memory and spatial navigation. It is crucial for forming new episodic memories, linking the “what, where, and when” of experiences. Damage to the hippocampus often causes anterograde amnesia, where a person can recall older memories but struggles to form new ones, illustrating its role in consolidation rather than long term storage.

Neurons in the hippocampus form maps of space using place cells. Each place cell becomes active when an animal is in a specific location, together creating a “cognitive map” of the environment. Related cells such as grid cells in nearby regions provide a metric for space, while head direction and boundary cells contribute orientation and landmark information. This system supports navigation, route planning, and the flexible use of spatial knowledge.

The hippocampus is also involved in imagining possible futures and recombining past experiences into novel scenarios, suggesting a general role in constructing internal models. It interacts closely with the prefrontal cortex, which helps organize and retrieve memories according to goals and context.

Hippocampal function is sensitive to stress, aging, and disease. Chronic stress and high levels of glucocorticoids can shrink hippocampal volume and impair memory. Early stages of Alzheimer’s disease prominently affect this region, contributing to memory loss and disorientation. At the same time, the hippocampus shows adult neurogenesis in some of its subregions, which may support learning and memory flexibility. Overall, research portrays the hippocampus as a dynamic hub for encoding, organizing, and updating our experiences in space and time.