What is the hippocampus?
The hippocampus is a brain region that belongs to the limbic cortex (limbic system). The name means “seahorse” because this brain region has a similar shape to the small sea creature. It belongs to the allocortex, which is a developmentally very old part of the cerebral cortex.
The hippocampus is part of a larger structure of the brain, the parahippocampal gyrus (a turn of the cerebral cortex), at the base of the temporal lobe. It consists of several structures that together form the hippocampal formation.
- Ammon’s horn (cornu ammonis): Hippocampus in the strict sense; consists of four zones.
- dentate gyrus (dentate-looking turn of the cerebral cortex)
- Subiculum (transitional area between parahippocampal gyrus and ammonic horn)
The fornix – an arcuate bundle of fibers – connects the hippocampus to the corpora mammilaria. These are two roundish elevations at the base of the diencephalon. There are also connections with other brain regions, including the olfactory brain.
What is the function of the hippocampus?
The hippocampus is the switching point between short-term and long-term memory. Via this switching point, content from short-term memory is transferred – depending on its significance – to long-term memory, where it can be stored and retrieved as needed.
Since the olfactory brain and hippocampus are located in close proximity, scents and smells that are linked to memories and stored are also evaluated positively or negatively.
Where is the hippocampus located?
The hippocampus is a crescent-shaped curved bulge at the base of the inferior horn of the lateral ventricles. It runs as a longitudinal bulge on the medial wall of the inferior horn.
What problems can the hippocampus cause?
As a mediator between short- and long-term memory, the hippocampus is a central switching point in the brain. If this area is disturbed, no new information can be stored in the brain.
In the case of an accident with concussion or an epileptic seizure, memory contents of events that took place seconds to hours before the event and have not yet been stably transferred to the long-term memory are erased – a retrograde amnesia (memory gap related to the time before the accident) develops. For the time after the accident – with unconsciousness of a few hours – there is an anterograde amnesia (memory gap related to the time after the accident), which can last for two following days.
