Dentate gyrus

Of the Dentate gyrus is part of the human brain. It is located in the hippocampus. The dentate gyrus is an important tool in the learning process.

What is the dentate gyrus?

The dentate gyrus is located in the brain and is part of the central nervous system. It is part of the hippocampal formation. This belongs to the limbic system. The processing of emotions and learning take place in the limbic system.

The hippocampus formation includes the gyrus denatatus, the Ammon's horn and the subilicum. The Ammon's horn is also known as Cornu ammonis. The hippocampus formation is located in the last part of the hippocampus. This is where the characteristic rolled-up bark structure is located. It is called the three-layer archicortex. The dentate gyrus is at the beginning of the curled structure and is therefore also seen as the entrance to the hippocampus. The memory consolidation takes place in the hippocampus.

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This includes the formation of long-term memories, knowledge of actions and conditioning. The hippocampus is shaped like a sea horse. It is located on the inner edge of the temporal lobe, also known as the temple lobe. The dentate gyrus is the main afferent system in the hippocampus. In contrast, the subilicum takes over most of the efferent system.

Anatomy & structure

The limbic system wraps around the basal ganglia and thalamus. It consists of different structures. This includes the hippocampus. It is located on the inside of the temporal lobe. A cross-section of the tissue reveals that the hippocampus has the shape of a seahorse. However, he lacks the head. The area of ​​the tail is curled up. The archicortex is located in it. This consists of a three-layer fabric. These three layers are formed by the dentate gyrus, the Ammon's horn and the subilicum.

While the subilicum forms the transition from the hippocampus to the enthorinal cortex, the dentate gyrus is the entrance area to the hippocampus. The dentate gyrus consists of the hilus, the granular cell band and a molecular layer. The granular cell band is called the stratum granulare. There are granule cells in it. The molecular layer is called the stratum molecular. A distinction is made between the inner and outer molecular layers. The dendrites of the granule cells are located in the two molecular layers. They establish the connection to the pyramidal cells of the Ammon's horn.

Function & tasks

The dentate gyrus is significantly involved in the consolidation of memory contents. This process involves learning. This includes building knowledge, but also learning about actions. Recorded information is transferred from working memory to long-term memory. Only when they are saved there can they be accessed for life. For most learning processes, the process of long-term consolidation takes several days to months.

The more emotional an event is, the faster it gets into long-term memory. An important process in creating long-term memories is repetition. If the process of long-term potentiation is interrupted, the information is incompletely or not at all transferred to long-term memory. With its granule cells, the dentate gyrus forms the first instance of the three layers in the hippocampus. They are all jointly responsible for long-term potentiation. It creates the basis for all long-term learning and memory content. This includes knowledge of facts and events. Spatial conditions as well as learned knowledge are part of it. They represent declarative memory.

In addition, preparations are made in the dentate gyrus so that the implicit memory can also be formed. Habits and actions are stored in implicit memory. Automatic processes such as tying the shoelaces are learned in the hippocampus and called up when necessary.

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Diseases

Lesions in the hippocampus lead to memory consolidation problems. Since the granule cells of the dentate gyrus forward the information received to the downstream pyramidal cells, damage in the dentate gyrus leads to a loss of memory.

Long-term potentiation is disturbed. It takes several days to months. As a result, lesions in the dentate gyrus mean that no new long-term memories can be formed. This can lead to decreased intelligence.

Memory disorders are known as amnesias. Doctors differentiate between anterograde and retrograde amnesia. As soon as no more new memory contents can be formed, they speak of anterograde amnesia. The long-term memories created up to the time of the lesion are retained.

However, new ones can no longer be created and saved. In retrograde amnesia, access to the memory content that has already arisen is no longer possible. All knowledge that was formed before the lesion must be relearned. Since all three layers of the hippocampus are involved in memory consolidation, damage or failure of a region leads to memory loss. In addition, there is an impairment of long-term memory formation. Since the dentate gyrus assumes a decisive function as the entrance gate in the long-term potentiation, all instances connected after it are dependent on its activity.

In diseases such as epilepsy, Alzheimer's or schizophrenia, the layers in the hippocampus play a key role. Seizures occur in epilepsy, the cause of which is to be found in a faulty discharge of neurons in the hippocampus. Schizophrenia is associated with significant thought disorders and hallucinations. Sick people have organic brain changes in the hippocampus. In Alzheimer's disease, receptor changes occur in the course of the disease. These are considered to be the cause of the memory impairment.