hippocampus

n. Part of the limbic system, a neural structure located in the medial-temporal lobe adjacent to the cerebral cortex, at the level of the lateral ventricle. The interior of the hippocampus is composed of gray matter (cell bodies), which is covered by white matter (nerve fiber pathways). The hippocampus plays an important role in declarative (cognitive) long-term memory consolidation, spatial memory, and emotional memory. Neural input to the hippocampus travels via pathways originating in cortical association areas which have processed information from all sensory modalities. Stimulation of this region increases the magnitude of excitatory postsynaptic potentials in postsynaptic neurons. This action is known as long-term potentiation, considered a possible neural template of memory formation. Lesions in the hippocampus and surrounding area may produce severe anterograde amnesia, which prevents the consolidation of new memories.

One of the causes of memory losses occurring in aging is degeneration of the hippocampus, possibly resulting from decreased blood circulation in this region. In the hippocampus, the problem of decreased circulation is heightened by the presence of stress hormones, particularly cortisol, to which the hippocampus is especially sensitive.

- VS