The dentate gyrus is a 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 a subarea of the hippocampal formation. This belongs to the limbic system. The processing of emotions as well as learning takes place in the limbic system. In addition to the denatatus gyrus, the hippocampal formation includes the ammonic horn and the subilicum. The ammonic horn is also referred to as the cornu ammonis. The hippocmapus formation is located in the last part of the hippocampus. It is there that the characteristically curled cortical structure is found. It is referred to as the three-layered archicortex. The dentate gyrus is located at the beginning of the inrolled structure and is therefore also seen as the entrance to the hippocampus. The hippocampus is where memory consolidation takes place. This includes the formation of long-term memories, knowledge about actions, and also conditioning. The hippocampus is shaped like a seahorse. It is located on the inner edge of the temporal lobe, which is also called the temporal lobe. The dentate gyrus is the main afferent system in the hippocampus. In contrast, the subilicum handles most of the efferent system.
Anatomy and structure
The limbic system wraps around the basal ganglia and thalamus. It is composed of several structures. These include the hippocampus. It is located on the inner surface of the temporal lobes. A cross-section of the tissue reveals that the hippocampus is shaped like a seahorse. However, it lacks a head. The area of the tail is curled up. Within it is the archicortex. This consists of a three-layered tissue. These three layers are formed by the dentate gyrus, the ammonic horn and the subilicum. While the subilicum as the terminal part 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 granule cell ligament, and a molecular layer. The granule cell band is called the stratum granulare. It contains granule cells. The molecular layer is called the stratum moleculare. It is divided into the inner and outer molecular layers. The dendrites of the granule cells are located in the two molecular layers. They connect to the pyramidal cells of the ammonium horn.
Function and tasks
The dentate gyrus is instrumental in the consolidation of memory content. This process involves learning. It includes the formation of knowledge, but also learning about actions. Recorded information passes from working memory to long-term memory. Only when it is stored there can it be retrieved for a lifetime. The process of long-term consolidation takes several days to months in most learning processes. The more emotional an event is, the faster it enters long-term memory. An important process in the formation of long-term memories is repetition. If the process of long-term potentiation is interrupted, the information is transferred into long-term memory incompletely or not at all. With its granule cells, the dentate gyrus forms the first instance of the three layers in the hippocampus. Together, they are responsible for long-term potentiation. It creates the basis of all long-term learning and memory content. This includes knowledge about facts and events. Spatial facts as well as learned knowledge are part of it. They represent the declarative memory. In addition, preparations are made in the dentate gyrus so that implicit memory can also be formed. In implicit memory, habits and actions are stored. Automatic processes such as tying shoelaces are learned in the hippocampus and recalled when needed.
Diseases
Lesions in the hippocampus lead to problems with memory consolidation. Because the granule cells of the dentate gyrus transmit the information they receive to the downstream pyramidal cells, damage to the dentate gyrus results in loss of memory. The long-term potentiation is disturbed. It requires several days to months. Therefore, lesions in the dentate gyrus result in the inability to form new long-term memories. This can lead to reduced intelligence. Disturbances of the memory are called amnesias.Doctors distinguish between anterograde and retrograde amnesia. As soon as no new memory content can be formed, they speak of anterograde amnesia. The long-term memories formed up to the time of the lesion are retained. However, new ones can no longer be formed and stored. In retrograde amnesia, access to the memory content that has already been formed is no longer possible. All knowledge formed before the lesion must be relearned. Since all three layers of the hippocampus are involved in memory consolidation, if one region is damaged or fails, memory loss occurs. In addition, there is impairment of long-term memory formation. Since the dentate gyrus plays a crucial role as the gateway in long-term potentiation, all instances downstream of it depend on its activity. In diseases such as epilepsy, Alzheimer’s or schizophrenia, the layers in the hippocampus are significantly involved. Seizures occur in epilepsy, the cause of which can be found in a faulty discharge of neurons in the hippocampus. Schizophrenia is accompanied by significant thought disorders and hallucinations. Sufferers show brain-organic changes in the hippocampus. In Alzheimer’s disease, receptor changes occur in the course of the disease. These are thought to be the cause of the memory impairment.