The Hippocampal Network
Published: 13.07.2015
Exciting synapses are described as excitatory when they depolarize the subsequent cell membrane and can thus lead to the formation of an Action potential An excitatory effect is usually produced by an exciting transmitter (messenger substance), such as Glutamate. The opposite is an inhibitory synapse.
Hippocampus
The hippocampus is the largest part of the Archicortex and an area in the Temporal lobe It is also an important part of the Limbic system Functionally, it is involved in Memory processes, but also in spatial orientation and learning. It comprises the subiculum, the dentate gyrus, and the Ammon's horn with its four fields CA1-CA4.
Changes in the structure of the hippocampus due to stress are associated with chronic pain. The hippocampus also plays an important role in the amplification of pain through anxiety.
Dentate gyrus
gyrus dentatus
The Dentate gyrus is part of the hippocampus and acts as its "input station." It receives various sensory inputs from the Cortex (cerebral cortex) via the entorhinal cortex. Its densely packed granule cells, which are found in the so-called granular layer, project almost exclusively to the CA3 region of the hippocampus.
Cortex
cortex cerebri
Cortex refers to a collection of neurons, typically in the form of a thin surface. However, it usually refers to the cerebral cortex, the outermost layer of the Cerebrum. It is 2.5 mm to 5 mm thick and rich in nerve cells. The cerebral cortex is heavily folded, comparable to a handkerchief in a cup. This creates numerous convolutions (gyri), fissures (fissurae), and sulci. Unfolded, the surface area of the cortex is approximately 1,800cm².
Hippocampus
The hippocampus is the largest part of the archicortex and an area in the temporal lobe. It is also an important part of the limbic system. Functionally, it is involved in memory processes, but also in spatial orientation and learning. It comprises the subiculum, the dentate gyrus, and the Ammon's horn with its four fields CA1-CA4.
Changes in the structure of the hippocampus due to stress are associated with chronic pain. The hippocampus also plays an important role in the amplification of pain through anxiety.
Fornix
The fornix is a nerve pathway consisting of approximately 12 million fibers that connects the hippocampus (one of the oldest structures in the brain in evolutionary terms) and subiculum with the septum and mammillary bodies.
excitatory
Exciting synapses are described as excitatory when they depolarize the subsequent cell membrane and can thus lead to the formation of an action potential. An excitatory effect is usually produced by an exciting transmitter (messenger substance), such as glutamate. The opposite is an inhibitory synapse.
Action potential
In excitable cells (e.g., neurons or muscle cells), very rapid changes in electrical potential occur across the cell membrane. This event is the basis for signal conduction along the axon of the nerve cell. The action potential continues along the cell membrane and, according to the all-or-nothing principle, only occurs when the cell has been sufficiently excited.
Glutamate
Glutamate is an amino acid and the most important excitatory neurotransmitter, which acts as a messenger substance in the transmission of information between neurons at their synapses.
Synapse
A synapse is a connection between two neurons and serves as a means of communication between them. It consists of a presynaptic region – the terminal button of the sender neuron – and a postsynaptic region – the region of the receiver neuron with its receptors. Between them lies the synaptic cleft.
Archicortex
An ancient structure of the cerebrum in terms of evolutionary development, which, in contrast to the isocortex (also called the neocortex), has a three-layer structure. The archicortex mainly comprises the hippocampal structures.
Temporal lobe
Lobus temporalis
The temporal lobe is one of the four lobes of the cerebrum and is located laterally (on the side) at the bottom. It contains important areas such as the auditory cortex and parts of Wernicke's area, as well as areas for higher visual processing; deep within it lies the medial temporal lobe with structures such as the hippocampus.
Limbic system
The limbic system is a functional unit in the brain. It consists of interconnected structures, primarily in the cerebrum and diencephalon. The structures assigned to the system vary depending on the source, but the most important components are the hippocampus, amygdala, cingulate gyrus, septum, and mammillary bodies. The limbic system is involved in autonomic and visceral processes as well as in mechanisms of emotion, memory, and learning. Some authors mistakenly reduce the limbic system to the emotional world by referring to it as the "emotional brain."
Memory
Memory is a generic term for all types of information storage in the organism. In addition to pure retention, this also includes the absorption of information, its organization, and retrieval.
Ammon's horn
cornu ammonis
Part of the cerebrum, specifically the front end of the hippocampus. The Cornu Ammonis is divided into fields CA1 to CA4. It owes its name to its shape, which resembles the horn of an ammon sheep.
Dentate gyrus
gyrus dentatus
The dentate gyrus is part of the hippocampus and acts as its "input station." It receives various sensory inputs from the cortex (cerebral cortex) via the entorhinal cortex. Its densely packed granule cells, which are found in the so-called granular layer, project almost exclusively to the CA3 region of the hippocampus.
Cortex
cortex cerebri
Cortex refers to a collection of neurons, typically in the form of a thin surface. However, it usually refers to the cerebral cortex, the outermost layer of the cerebrum. It is 2.5 mm to 5 mm thick and rich in nerve cells. The cerebral cortex is heavily folded, comparable to a handkerchief in a cup. This creates numerous convolutions (gyri), fissures (fissurae), and sulci. Unfolded, the surface area of the cortex is approximately 1,800cm².
Cerebrum
telencephalon
The cerebrum comprises the cerebral cortex (gray matter), the nerve fibers (white matter), and the basal ganglia. It is the largest part of the brain. The cortex can be divided into four cortical areas: the temporal lobe, frontal lobe, occipital lobe, and parietal lobe.
Its functions include the coordination of perception, motivation, learning, and thinking.
Collaterals
Collaterals are the side branches or secondary branches of blood vessels and axons.
Subiculum
The transition zone between the cornu ammonis and the entorhinal cortex is called the subiculum.
Septum
area septalis
The septal nuclei are located medially in the basal forebrain, near the anterior tip of the cingulate gyrus. They are connected to the olfactory cortex and linked to other limbic structures via the fornix. Functionally, they play a role in emotional processes and reward processing.
