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Periallocortex
Periallocortex is one of three subtypes of allocortex, the other two subtypes being paleocortex and archicortex. The periallocortex is formed at transition areas where any of the other two subtypes of allocortex borders with the neocortex (which is also called isocortex). Thus, the periallocortex is also subdivided to two subtypes. One subtype is called peripaleocortex, which is formed at borders between paleocortex and neocortex. Areas considered to belong to peripaleocortex are for example anterior insular cortex. Another subtype of periallocortex is called periarchicortex. It is formed at borders between archicortex and neocortex. Areas considered to belong to periarchicortex include entorhinal cortex, perirhinal cortex, presubiculum, parasubiculum, retrosplenial cortex, subcallosal area and subgenual area. No one allocortex or even periallocortex area borders, contacts or transitions immediately to the so-called true isocortex. Instead, they border and slowly transition to an ...
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Allocortex
The allocortex (from Latin allo-, meaning other, and cortex, meaning bark or crust), or heterogenetic cortex, is one of the two types of cerebral cortex in the brain, together with the neocortex. In the human brain, the allocortex is the much smaller area of cortex taking up just 10%; the neocortex takes up the remaining 90%. It is characterized by having just three cortical layers (one main neural layer), in contrast with the six cortical layers of the neocortex. There are three subtypes of allocortex: the paleocortex, the archicortex, and the periallocortex—a transitional zone between the neocortex and the allocortex. The specific regions of the brain usually described as belonging to the allocortex are the olfactory system and the hippocampus. Allocortex is termed heterogenetic cortex, because during development it never has the six-layered architecture of homogenetic neocortex. It differs from heterotypic cortex, a type of cerebral cortex, which during prenatal development ...
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Proisocortex
Proisocortex or pro-isocortex is one of two subtypes of cortical areas in the areas belonging to the neocortex. The other subtype is termed the true isocortex. Proisocortical areas are transitional areas placed between areas of true isocortex and areas of periallocortex (which themselves are transitional between "true" allocortex and proisocortex). The histological structure of proisocortex is also transitional between true isocortex and either peripaleocortex or periarchicortex, depending on with which subtype of periallocortex the given proisocortical area borders. Proisocortex is found in the cingulate cortex (part of the limbic system), in Brodmann's areas 24, 25, 30 and 32, the insula and parahippocampal gyrus. The transitional cortical areas from isocortical side (i.e. proisocortex) and from allocortical side (i.e. periarchicortex and peripaleocortex) together are called mesocortex. The mesocortex is essentially the same as paralimbic cortex, as all mesocortical t ...
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Periarchicortex
Periarchicortex is one of two subtypes of periallocortex, the other being peripaleocortex. It is formed at borders between archicortex (a subtype of allocortex) and isocortex and shows slow histological transition from the four-layered structure typical for archicortex to the six-layered structure typical for isocortex. Cortical areas that are generally considered to belong to periarchicortex, include presubiculum, parasubiculum, entorhinal cortex, perirhinal cortex, retrosplenial cortex, periarchicortical part of cingulate cortex, posterior part of subcallosal area, and subgenual area. Periarchicortex does not contact immediately at borders with the true isocortex and does not transit directly into it. Instead, another transitional area from the isocortex side, called proisocortex Proisocortex or pro-isocortex is one of two subtypes of cortical areas in the areas belonging to the neocortex. The other subtype is termed the true isocortex. Proisocortical areas are transitional a ...
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Mesocortex
The paralimbic cortex is an area of three-layered cortex that includes the following regions: the piriform cortex, entorhinal cortex, the parahippocampal cortex on the medial surface of the temporal lobe, and the cingulate cortex just above the corpus callosum.Kolb & Whishaw: ''Fundamentals of Human Neuropsychology'', 2003. The paralimbic cortex lies close to, and is directly connected with, the structures of the limbic system. (The prefix ''para'' meaning beside or adjacent to.) The paralimbic cortex, also referred to as mesocortex, or juxtallocortex, is interposed between the neocortex and the allocortex. The paralimbic cortex provides a gradual transition from primary limbic regions, including the septal region, substantia innominata, and the amygdala nuclei, to higher neocortical regions. There are dense connections between the paralimbic cortex and core limbic structures, in particular the amygdala. The amygdaloid complex comprises both nuclear and cortical layers. These ...
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Peripaleocortex
Peripaleocortex is one of two subtypes of periallocortex, the other being periarchicortex. Peripaleocortex is formed at borders between isocortex (neocortex) and paleocortex (a subtype of allocortex). It shows slow histological transition from the three-layered structure characteristic of paleocortex to the typical six-layered structure characteristic of isocortex. The main peripaleocortex area is anterior insular cortex. Peripaleocortex does not histologically transit directly to the true isocortex. Instead, at borders between peripaleocortex and isocortex, there are other transitional areas from the isocortex side, called proisocortex Proisocortex or pro-isocortex is one of two subtypes of cortical areas in the areas belonging to the neocortex. The other subtype is termed the true isocortex. Proisocortical areas are transitional areas placed between areas of true isocortex and .... Thus, at borders between paleocortex and isocortex, there are two transitional areas. One trans ...
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Neocortex
The neocortex, also called the neopallium, isocortex, or the six-layered cortex, is a set of layers of the mammalian cerebral cortex involved in higher-order brain functions such as sensory perception, cognition, generation of motor commands, spatial reasoning, and language. The neocortex is further subdivided into the true isocortex and the proisocortex. In the human brain, the cerebral cortex consists of the larger neocortex and the smaller allocortex, respectively taking up 90% and 10%. The neocortex is made up of six layers, labelled from the outermost inwards, I to VI. Etymology The term is from ''cortex'', Latin, " bark" or "rind", combined with ''neo-'', Greek, "new". ''Neopallium'' is a similar hybrid, from Latin ''pallium'', "cloak". ''Isocortex'' and ''allocortex'' are hybrids with Greek ''isos'', "same", and ''allos'', "other". Anatomy The neocortex is the most developed in its organisation and number of layers, of the cerebral tissues. The neocortex cons ...
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Archicortex
The archicortex, or archipallium, is the phylogenetically second oldest region of the brain's cerebral cortex (the oldest is the paleocortex). In older species, such as fish, the archipallium makes up most of the cerebrum. Amphibians develop an archipallium and paleopallium. In humans, the archicortex makes up the three cortical layers of the hippocampus. It has fewer cortical layers than both the neocortex, which has six, and the paleocortex, which has either four or five. The archicortex, along with the paleocortex and periallocortex, is a subtype of allocortex. Because the number of cortical layers that make up a type of cortical tissue seems to be directly proportional to both the information-processing capabilities of that tissue and its phylogenetic age, the archicortex is thought to be the oldest and most basic type of cortical tissue. Location The archicortex is most prevalent in the olfactory cortex and the hippocampus, which are responsible for processing smells ...
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Insular Cortex
The insular cortex (also insula and insular lobe) is a portion of the cerebral cortex folded deep within the lateral sulcus (the fissure separating the temporal lobe from the parietal lobe, parietal and frontal lobes) within each brain hemisphere, hemisphere of the mammalian brain. The insulae are believed to be involved in consciousness and play a role in diverse functions usually linked to emotion or the regulation of the body's homeostasis. These functions include compassion, empathy, taste, perception, motor control, self-awareness, cognitive functioning, interpersonal relationships, and awareness of homeostatic emotions such as Hunger (physiology), hunger, pain and fatigue. In relation to these, it is involved in psychopathology. The insular cortex is divided by the central sulcus of the insula, into two parts: the anterior insula and the posterior insula in which more than a dozen field areas have been identified. The cortical area overlying the insula toward the lateral su ...
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Perirhinal Cortex
The perirhinal cortex is a brain cortex, cortical region in the medial temporal lobe that is made up of Brodmann areas Brodmann area 35, 35 and Brodmann area 36, 36. It receives highly processed sensory information from all sensory regions, and is generally accepted to be an important region for memory. It is bordered caudally by postrhinal cortex or parahippocampal gyrus, parahippocampal cortex (homologous regions in rodents and primates, respectively) and ventrally and Anatomical terms of location#Left and right (lateral), and medial, medially by entorhinal cortex. Structure The perirhinal cortex is composed of two regions: areas 36 and 35. Area 36 is sometimes divided into three subdivisions: 36d is the most rostral and dorsal, 36r ventral and caudal, and 36c the most caudal. Area 35 can be divided in the same manner, into 35d and 35v (for dorsal and ventral, respectively). Area 36 is six-layered, dysgranular, meaning that its layer IV is relatively sparse. Area 35 is agran ...
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Presubiculum
Brodmann area 27 is a cytoarchitecturally defined cortical area that is a rostral part of the parahippocampal gyrus. It is commonly regarded as a synonym of presubiculum. The dorsal part of the presubiculum is more commonly known as the postsubiculum, and is of interest because it contains head direction cells, which are responsive to the facing direction of the head. See also * Brodmann area * List of regions in the human brain The human brain anatomical regions are ordered following standard neuroanatomy hierarchies. Functional, connective, and developmental regions are listed in parentheses where appropriate. Hindbrain (rhombencephalon) Myelencephalon * M ... References External links * For Neuroanatomy of this area visiBrainInfo 27 Medial surface of cerebral hemisphere {{neuroanatomy-stub ...
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Parasubiculum
In the rodent, the parasubiculum is a retrohippocampal isocortical structure, and a major component of the subicular complex. It receives numerous subcortical and cortical inputs, and sends major projections to the superficial layers of the entorhinal cortex (Amaral & Witter, 1995). The parasubicular area is a transitional zone between the presubiculum and the entorhinal area in the mouse (Paxinos-2001), the rat (Swanson, 1998) and the primate (Zilles, 1990). Defined on the basis of cytoarchitecture, it is more similar to the presubiculum than to the entorhinal area (Zilles, 1990), however electrophysiological evidence suggests a similarity with the entorhinal cortex (Funahashi and Stewart, 1997; Glasgow & Chapman, 2007). To be specific, cells in this area are modulated by local theta rhythm, and display theta-frequency membrane potential oscillations (Glasgow & Chapman, 2007; Taube, 1995). Furthermore, cells in the parasubiculum, and neighboring presubiculum, fire in relat ...
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