The Ammonhorn is a part of the brain. It is located in the hippocampus and is located in the rolled-up bark structure there. It has an important role in the learning process.

What is the Ammonhorn?

The Ammonshorn is medically referred to as Cornu ammonis. In some sources it is also called Hippocampus proprius. The ammons horn forms part of the internal structure of the hippocampus. This is located for the most part in the inner edge of the temporal lobe.

This area is also called temporal lobe. The hippocampus is responsible for learning, emotions and memory formation. He is seen as part of the limbic system. The Ammonshorn contributes significantly to the learning process. It forms the basis for the formation of long-term memories.

The hippocampus contains the archicortex. This is three-layered and is considered a hippocampus formation. The three layers are distinguished into the dentate gyrus, the ammone horn and the subiculum. The dentate gyrus is the most important afferent system in the hippocampus. The subiculum forms a major part of the efferent system of the hippocampus. Therefore, most information in the hippocampus flows through the dentate gyrus as well as the subiculum. The Ammonshorn can differ in four regions due to the different tissue structure. These are called CA1, CA2, CA3 and CA4.

Anatomy & Construction

The hippocampus is located on the inside of the temporal lobes. It visually has the shape of the body of a seahorse without the head. As soon as a frontal incision is made in the lower part of the tail, the three layers, the dentate gyrus, the ammus horn and the subiculum become visible.

In this area, the tissue has a very characteristic structure. It is called a rolled up bark structure. This microscopic archicortex structure is divided into three layers. The area of ​​the Ammonshorn is subdivided into various fields of cytoarchitectural structure. These are four sectors named CA1-CA4. The field CA1 contains many small pyramidal cells. The CA2 field contains particularly large pyramidal cells.

These are packed tight. The same large cells are also in field CA3. Here, however, they are loosely arranged. In the field CA4, the distances between the cells are even greater. The cell-rich layer is called pyramidal stratum. The dendrites of the pyramidal cells radiate into the stratum radiatum. From there they continue to the stratum lacunosum and the stratum moleculare.

Function & Tasks

The Ammonshorn has an important role in memory consolidation. These are learning or learning processes. This refers to the process that transfers the information from short-term memory to long-term memory. This takes a time window of a few days to months. Only then are the memories permanently stored in the memory.

In the Ammonshorn the so-called long-term potentiation takes place. This serves as the basis of all learning and memory processes. This applies mainly to the long-term memories and the knowledge formation in the declarative memory. Here information such as facts and events are stored. These include factual relationships as well as spatial conditions. In addition, the Ammonhorn is also involved in the formation of implicit memory. These memory contents include actions, habits, motor learning, and emotional learning.

The pyramidal cells in the ammone horn are responsible for the long-term potentiation. This only works if the potentiating pulses arrive at a sufficiently high speed. Otherwise, the information is extinguished after a short time. Thus, the Ammonshorn is responsible for the prerequisite as well as the formation of the memory contents. As described above, the ammone horn is divided into four fields. The CA1-CA3 regions play an important role in operant conditioning. It is the learning of certain stimulus-response patterns.


The pyramidal cells of the Ammonshorn are particularly vulnerable to alcohol abuse. Regular use of alcohol leads to addiction after several years. In severe cases, this can lead to Wernicke encephalopathy or Korsakoff syndrome.

As a result of alcohol abuse, confabulation occurs in the patient. Patients can no longer rely on their own memories. That's why they come up with answers to questions or entire stories. Her statements are true and logical. Nevertheless, it is a production of objectively false statements or narratives. Patients with the described disorders are unable to admit the absence of memories. The confabulation takes place as a result of the disease.

The disturbance of memory is basically called amnesia. Anterograde and retrograde amnesia should be distinguished from each other. Anterogerial amnesia has the consequence that no new memory formation is possible. In retrograde amnesia, the memory contents that have arisen before brain damage are no longer available. They are partially or completely deleted.

The Ammonshorn plays an essential role in the formation of memory content. Impairment of its functioning lead in particular to problems in the long-term memory formation.

A lesion of the hippocampus as a result of circulatory disorders or brain inflammation lead in addition to the loss of memory to complete temporal and local disorientation. Defects of the hippocampus are also of relevance in diseases such as epilepsy beyond the specific forms of memory disorders. The Ammonshornsklerose is considered the most common neuropathological findings in a temporal lobe epilepsy. This is a special form of epilepsy.

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