Image 1: The human hippocampus and fornix (left) compared with a seahorse (right) Hippocampal place cells interact extensively with head direction cells, whose activity acts as an inertial compass, and conjecturally with grid cells in the neighboring entorhinal cortex. Many neurons in the rat and mouse hippocampus respond as place cells: that is, they fire bursts of action potentials when the animal passes through a specific part of its environment. In rodents as model organisms, the hippocampus has been studied extensively as part of a brain system responsible for spatial memory and navigation. LTP is widely believed to be one of the main neural mechanisms by which memories are stored in the brain. The form of neural plasticity known as long-term potentiation (LTP) was initially discovered to occur in the hippocampus and has often been studied in this structure. Since different neuronal cell types are neatly organized into layers in the hippocampus, it has frequently been used as a model system for studying neurophysiology. People with extensive, bilateral hippocampal damage may experience anterograde amnesia: the inability to form and retain new memories. Damage to the hippocampus can also result from oxygen starvation ( hypoxia), encephalitis, or medial temporal lobe epilepsy. In Alzheimer's disease (and other forms of dementia), the hippocampus is one of the first regions of the brain to suffer damage short-term memory loss and disorientation are included among the early symptoms. In humans, it contains two main interlocking parts: the hippocampus proper (also called Ammon's horn), and the dentate gyrus. The hippocampus, as the medial pallium, is a structure found in all vertebrates. The hippocampus is located in the allocortex, with neural projections into the neocortex in humans, as well as primates. The hippocampus is part of the limbic system, and plays important roles in the consolidation of information from short-term memory to long-term memory, and in spatial memory that enables navigation.

Humans and other mammals have two hippocampi, one in each side of the brain.

The hippocampus (via Latin from Greek ἱππόκαμπος, ' seahorse') is a major component of the brain of humans and other vertebrates.

How many neurons in a monkey brain