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Encyclopedia > Neocortex

The neocortex (Latin for "new bark" or "new rind") is a part of the brain of mammals. It is the top layer of the cerebral hemispheres, 2-4 mm thick, and is involved in higher functions such as sensory perception, generation of motor commands, spatial reasoning, conscious thought, and and in humans, language. Other names for the neocortex include neopallium ("new mantle") and isocortex ("equal rind"). Latin is an ancient Indo-European language originally spoken in the region around Rome called Latium. ... Bark is the outermost layer of stems and roots of woody plants such as trees. ... In botany, a rind is the thick outer skin of various structures such as fruit. ... Comparative brain sizes In animals, the brain, or encephalon (Greek for in the head), is the control center of the central nervous system. ... Orders Subclass Multituberculata (extinct) Plagiaulacida Cimolodonta Subclass Palaeoryctoides (extinct) Subclass Triconodonta (extinct) Subclass Eutheria (includes extinct ancestors)/Placentalia (excludes extinct ancestors) Afrosoricida Artiodactyla Carnivora Cetacea Chiroptera Cimolesta (extinct) Creodonta (extinct) Condylarthra (extinct) Dermoptera Desmostylia (extinct) Dinocerata (extinct) Embrithopoda (extinct) Hyracoidea Insectivora Lagomorpha Litopterna (extinct) Macroscelidea Mesonychia (extinct) Notoungulata (extinct) Perissodactyla... The human brain as viewed from above, showing the cerebral hemispheres. ... To help compare different orders of magnitude this page lists lengths between 10-3 m and 10-2 m (1 mm and 1 cm). ... Senses are the physiological methods of perception. ... // Early work on motor cortex function Back in the 1940s, Canadian neurosurgeon Wilder Penfield wanted to know which bits of epileptics brains he could suck out without them noticing. ... Consciousness is a quality of the mind generally regarded to comprise qualities such as subjectivity, self-awareness, sentience, sapience, and the ability to perceive the relationship between oneself and ones environment. ... A Mantle is a layer of the Earth below the crust and above the core. ...

Contents


Anatomy

The neocortex consists of grey matter surrounding the deeper white matter of the cerebrum. While the neocortex is smooth in rats and some other small mammals, it has deep grooves (sulci) and wrinkles (gyri) in primates and several other mammals. These folds serve to increase the area of the neocortex considerably. In humans it accounts for about 80% of the brain's weight. Grey matter is a major component of the central nervous system, consisting of nerve cell bodies and short nerve cell extensions/processes (axons and dendrites). ... White matter is one of the two main solid components of the central nervous system. ... For other articles about other subjects named brain see brain (disambiguation). ... Species 50 species; see text *Several subfamilies of Muroids include animals called rats. ... A sulcus (pl. ... Grays FIG. 726– Lateral surface of left cerebral hemisphere, viewed from the side. ... Families 15, See classification A primate (L. prima, first) is any member of the biological order Primates, the group that contains all the species commonly related to the lemurs, monkeys, and apes, with the latter category including humans. ... Trinomial name Homo sapiens sapiens Linnaeus, 1758 Humans, or human beings, are animals biologically classified as bipedal primates belonging to the mammalian genus Homo, in particular to its only extant species, Homo sapiens (Latin for wise man or knowing man), under the family Hominidae (the great apes). ...


The structure of the cortex is relatively uniform (whence the names "iso" and "homotypical"): it consists of six horizontal layers segregated by cell type, neuronal input, or cell density. The neurons are arranged in structures called neocortical columns. These are patches of the neocortex with a diameter of about 0.5 mm (and a depth of 2 mm). Each column typically responds to a sensory stimulus representing a certain body part or region of sound or vision. These columns are similar and can be thought of as the basic repeating functional units of the neocortex. In humans, the neocortex consists of millions of these columns, and each column has up to 100,000 neurons per square millimeter. Cells in culture, stained for keratin (red) and DNA (green). ... Drawing by Santiago Ramón y Cajal of cells in the pigeon cerebellum. ... A cortical column is a group of neurons in the brain cortex which can be successively penetrated by a probe inserted perpendicularly to the cortical surface, and which have nearly identical receptive fields. ... A schematic representation of hearing. ... Vision may mean: Visual perception via the visual system, one of the senses. ...


The neocortex is divided into several lobes, and different regions of the neocortex have different functions. (See Cerebral cortex and Cerebrum.) Location of the cerebral cortex Slice of the cerebral cortex, ca. ... For other articles about other subjects named brain see brain (disambiguation). ...


Evolution

With respect to evolution, the neocortex is the newest part of the cerebral cortex (whence the name "neo"); the other parts of the cerebral cortex are the paleocortex and archicortex, collectively known as the allocortex. The cellular organization of the allocortex is different from the six-layer structure mentioned above. In humans, 90% of the cerebral cortex is neopallium. A speculative phylogenetic tree of all living things, based on rRNA gene data, showing the separation of the three domains, bacteria, archaea and eukaryotes. ... Location of the cerebral cortex Slice of the cerebral cortex, ca. ... Archicortex is basically categorized under allocortex. ... Ö“üÅ[[]]→óùÄŒ ...


The six-layer cortex appears to be a distinguishing feature of mammals: It has been found in the brains of all mammals but not in any other animals. There is some debate[1][2], however, as to the cross-species nomenclature for neocortex. In avians, for instance, there are clear examples of cognitive processes that are thought to be neocortical in nature, despite the lack of the distinctive six-layer neocortical structure. In a similar manner, reptiles, such as turtles, have primary sensory cortices. A consistent, alternative name has yet to be agreed upon. In biology, a species is the basic unit of biodiversity. ... Orders Many - see section below. ... Orders See text. ...


See also

Human brain image constructed from MRI data // Brain (neural tube) Brainstem (rhombencephalon),(mesencephalon) Rhombencephalon (hindbrain) Metencephalon pons fourth ventricle cerebellum cerebellar vermis cerebellar hemispheres anterior lobe posterior lobe flocculonodular lobe cerebellar nuclei fastigial nucleus globose nucleus emboliform nucleus dentate nucleus Myelencephalon medulla oblongata medullary pyramids Mesencephalon (midbrain) tectum inferior colliculi... Blue Brain is the promotional name for the IBM project to simulate a human brain on the molecular level. ...

References

  1.   Jarvis ED, Gunturkun O, Bruce L, Csillag A, Karten H, Kuenzel W, Medina L, Paxinos G, Perkel DJ, Shimizu T, Striedter G, Wild JM, Ball GF, Dugas-Ford J, Durand SE, Hough GE, Husband S, Kubikova L, Lee DW, Mello CV, Powers A, Siang C, Smulders TV, Wada K, White SA, Yamamoto K, Yu J, Reiner A, Butler AB (2005). "Avian brains and a new understanding of vertebrate brain evolution". Nat Rev Neurosci 6 (2): 151-9. PMID 15685220.
  2.   Reiner A, Perkel DJ, Bruce LL, Butler AB, Csillag A, Kuenzel W, Medina L, Paxinos G, Shimizu T, Striedter G, Wild M, Ball GF, Durand S, Gunturkun O, Lee DW, Mello CV, Powers A, White SA, Hough G, Kubikova L, Smulders TV, Wada K, Dugas-Ford J, Husband S, Yamamoto K, Yu J, Siang C, Jarvis ED (2004). "Revised nomenclature for avian telencephalon and some related brainstem nuclei". J Comp Neurol 473 (3): 377-414. PMID 15116397.

  Results from FactBites:
 
Neocortex - Wikipedia, the free encyclopedia (476 words)
The neocortex (Latin for "new bark" or "new rind") is a part of the brain of mammals.
The neocortex consists of grey matter surrounding the deeper white matter of the cerebrum.
With respect to evolution, the neocortex is the newest part of the cerebral cortex (whence the name "neo"); the other parts of the cerebral cortex are the paleocortex and archicortex, collectively known as the allocortex.
Molecular regionalization of the neocortex is disrupted in Fgf8 hypomorphic mutants -- Garel et al. 130 (9): 1903 -- ... (6722 words)
Molecular regionalization of the neocortex is disrupted in Fgf8 hypomorphic mutants -- Garel et al.
In Fgf8neo/neo embryos, the neocortex primordium and the bulks of the ventral telencephalic ganglionic eminences are present.
Molecular regionalization of the neocortex is perturbed in `mild' Fgf8neo/neo neonates.
  More results at FactBites »

 
 

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