EC-hippocampus system
Encyclopedia
The Entorhinal Cortex
(EC) is a major part of the hippocampal formation
of the human brain
, and is reciprocally connected with the hippocampus
.
The hippocampal formation, which consists of the hippocampus, perirhinal cortex
, the dentate gyrus
, the subicular
areas and EC forms one of the most important parts of limbic system
. It is an infolding of the parahippocampal gyrus
into the inferior (temporal) horn of the lateral ventricle
.
, limbic, and parieto-occipital-temporal) to form visual, auditory and somatic information. From there, the information is then conveyed in series to the parahippocampal and perirhinal cortices, then onwards to the EC, dentate gyrus, hippocampus, subiculum
and then finally back to the EC. From the EC, the information is sent back to the parahippocampal and perirhinal cortex, and finally back to the polymodal association areas of neocortex
.
The EC has dual functions in processing information for explicit memory storage: First, it is the main input to the hippocampus. The EC projects to the dentate gyrus via the perforant pathway and by this means provides the critical input pathway in this area of the brain, linking the association cortices to the hippocampus. Second, the EC is also the major output of the hippocampus. The information coming to the hippocampus from both the poly- and unimodal association cortices, converge in the EC.
s in temporal lobe
epilepsy
, one of the most common forms of epilepsy. This, coupled with the rich innervation of the hippocampus, is the reason why the EC is so widely studied by neurophysiologists and neuropharmacologist
s.
Entorhinal cortex
The entorhinal cortex is located in the medial temporal lobe and functions as a hub in a widespread network for memory and navigation. The EC is the main interface between the hippocampus and neocortex...
(EC) is a major part of the hippocampal formation
Hippocampal formation
The hippocampal formation is a compound structure in the medial temporal lobe of the brain. There is currently no consensus concerning which brain regions are encompassed by the term, with some authors defining it as the dentate gyrus, the hippocampus proper and the subiculum; and others including...
of the human brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
, and is reciprocally connected with the hippocampus
Hippocampus
The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...
.
The hippocampal formation, which consists of the hippocampus, perirhinal cortex
Perirhinal cortex
Perirhinal cortex is a cortical region in the medial temporal lobe that is made up of Brodmann areas 35 and 36. In rats, it is located along and dorsal to the rhinal sulcus. It receives highly-processed sensory information from all sensory regions, and is generally accepted to be an important...
, the dentate gyrus
Dentate gyrus
The dentate gyrus is part of the hippocampal formation. It is thought to contribute to new memories as well as other functional roles. It is notable as being one of a select few brain structures currently known to have high rates of neurogenesis in adult rats, .The dentate gyrus cells receive...
, the subicular
Subiculum
The subiculum is the most inferior component of the hippocampal formation. It lies between the entorhinal cortex and the CA1 subfield of the hippocampus proper.-Paths:...
areas and EC forms one of the most important parts of limbic system
Limbic system
The limbic system is a set of brain structures including the hippocampus, amygdala, anterior thalamic nuclei, septum, limbic cortex and fornix, which seemingly support a variety of functions including emotion, behavior, long term memory, and olfaction. The term "limbic" comes from the Latin...
. It is an infolding of the parahippocampal gyrus
Parahippocampal gyrus
The parahippocampal gyrus is a grey matter cortical region of the brain that surrounds the hippocampus. This region plays an important role in memory encoding and retrieval....
into the inferior (temporal) horn of the lateral ventricle
Ventricle (heart)
In the heart, a ventricle is one of two large chambers that collect and expel blood received from an atrium towards the peripheral beds within the body and lungs. The Atria primes the Pump...
.
Role in knowledge processing and memory
Studies, with human patients and with experimental animals, suggest that knowledge stored as explicit memory is first acquired through processing in one or more of the three polymodal association cortices (prefrontalPrefrontal cortex
The prefrontal cortex is the anterior part of the frontal lobes of the brain, lying in front of the motor and premotor areas.This brain region has been implicated in planning complex cognitive behaviors, personality expression, decision making and moderating correct social behavior...
, limbic, and parieto-occipital-temporal) to form visual, auditory and somatic information. From there, the information is then conveyed in series to the parahippocampal and perirhinal cortices, then onwards to the EC, dentate gyrus, hippocampus, subiculum
Subiculum
The subiculum is the most inferior component of the hippocampal formation. It lies between the entorhinal cortex and the CA1 subfield of the hippocampus proper.-Paths:...
and then finally back to the EC. From the EC, the information is sent back to the parahippocampal and perirhinal cortex, and finally back to the polymodal association areas of neocortex
Neocortex
The neocortex , also called the neopallium and isocortex , is a part of the brain of mammals. It is the outer layer of the cerebral hemispheres, and made up of six layers, labelled I to VI...
.
The EC has dual functions in processing information for explicit memory storage: First, it is the main input to the hippocampus. The EC projects to the dentate gyrus via the perforant pathway and by this means provides the critical input pathway in this area of the brain, linking the association cortices to the hippocampus. Second, the EC is also the major output of the hippocampus. The information coming to the hippocampus from both the poly- and unimodal association cortices, converge in the EC.
Role in epilepsy
The entorhinal cortex and its links to the hippocampus have been implicated in the generation of seizureSeizure
An epileptic seizure, occasionally referred to as a fit, is defined as a transient symptom of "abnormal excessive or synchronous neuronal activity in the brain". The outward effect can be as dramatic as a wild thrashing movement or as mild as a brief loss of awareness...
s in temporal lobe
Temporal lobe
The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both cerebral hemispheres of the mammalian brain....
epilepsy
Epilepsy
Epilepsy is a common chronic neurological disorder characterized by seizures. These seizures are transient signs and/or symptoms of abnormal, excessive or hypersynchronous neuronal activity in the brain.About 50 million people worldwide have epilepsy, and nearly two out of every three new cases...
, one of the most common forms of epilepsy. This, coupled with the rich innervation of the hippocampus, is the reason why the EC is so widely studied by neurophysiologists and neuropharmacologist
Neuropharmacology
Neuropharmacology is the study of how drugs affect cellular function in the nervous system. There are two main branches of neuropharmacology: behavioral and molecular. Behavioral neuropharmacology focuses on the study of how drugs affect human behavior , including the study of how drug dependence...
s.