The neocortex (Latin Latin or sometimes Roman is an Italic language originally spoken in Latium and Ancient Rome. Although often considered a dead language, in view of the fact that it has no native, fluent speakers, Latin continues to be taught in schools and has been, and currently is, used in the process of new word production in modern languages from many for "new bark Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner bark, which in older stems is living tissue, includes" or "new rind"), also called the neopallium ("new mantel Fireplace mantel or mantelpiece, also known as a chimneypiece, originated in medieval times as a hood that projected over a grate to catch the smoke. The term has evolved to include the decorative framework around the fireplace, and can include elaborate designs extending to the ceiling. Mantelpiece is now the general term for the jambs, mantel") and isocortex ("equal rind"), is a part of the brain The brain is the center of the nervous system in all vertebrate, and most invertebrate, animals. Some primitive animals such as jellyfish and starfish have a decentralized nervous system without a brain, while sponges lack any nervous system at all. In vertebrates, the brain is located in the head, protected by the skull and close to the primary of mammals Mammals are a class of vertebrate, air-breathing animals whose females are characterized by the possession of mammary glands while both males and females are characterized by hair and/or fur, three middle ear bones used in hearing, and a neocortex region in the brain. Some mammals have sweat glands, but most do not. It is the outer layer of the cerebral hemispheres A cerebral hemisphere is defined as one of the two regions of the brain that are delineated by the body's median plane, (medial longitudinal fissure). The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres has an outer layer of grey matter called the cerebral cortex that is supported by, and made up of six layers, labelled I to VI (with VI being the innermost and I being the outermost). The neocortex is part of the cerebral cortex The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different composition in terms of neurons and connectivity. The human (along with the archicortex Archicortex is basically categorized under allocortex. It is any cortex with fewer than six layers, specifically three layered hippocampal cortexes. It is necessary for hippocampus formation and paleocortex The paleocortex is a layer of the cerebral cortex intermediate phylogenetically between the neocortex and archicortex, which are cortical parts of the limbic system The limbic system is a set of brain structures including the hippocampus, amygdala, anterior thalamic nuclei, and limbic cortex, which suggestively support a variety of functions including emotion, behavior, long term memory, and olfaction. The term "limbic" comes from the Latin limbus, for "border" or "edge". Some). It is involved in higher functions such as sensory perception Senses are the physiological capacities within organisms that provide inputs for perception. The senses and their operation, classification, and theory are overlapping topics studied by a variety of fields, most notably neuroscience, cognitive psychology , and philosophy of perception. The nervous system has a specific sensory system or organ,, generation of motor commands Motor cortex is a term that describes regions of the cerebral cortex involved in the planning, control, and execution of voluntary motor functions, spatial reasoning, conscious thought Consciousness is variously defined as subjective experience, or awareness, or wakefulness, or the executive control system of the mind. It is an umbrella term that may refer to a variety of mental phenomena. Although humans realize what everyday experiences are, consciousness refuses to be defined, philosophers note : and language Language is a term most commonly used to refer to so called "natural languages" — the forms of communication considered peculiar to humankind. By extension the term also refers to the type of human thought process which creates and uses language. Essential to both meanings is the systematic creation, maintenance and use of systems of.

Anatomy

The neocortex consists of the grey matter Grey matter is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil , glial cells (astroglia and oligodendrocytes) and capillaries. Grey matter contains neural cell bodies, in contrast to white matter, which does not and mostly contains myelinated axon tracts. The color difference arises mainly from the, or neuronal cell bodies and unmyelinated Myelin is a dielectric material that forms a layer, the myelin sheath, usually around only the axon of a neuron. It is essential for the proper functioning of the nervous system. Myelin is an outgrowth of a glial cell. Schwann cells supply the myelin for peripheral neurons, whereas oligodendrocytes, specifically of the interfascicular type, fibers, surrounding the deeper white matter White matter is one of the two components of the central nervous system and consists mostly of myelinated axons. White matter tissue of the freshly cut brain appears pinkish white to the naked eye because myelin is composed largely of lipid tissue veined with capillaries. Its white color is due to its usual preservation in formaldehyde. A 20 year- (myelinated Myelin is a dielectric material that forms a layer, the myelin sheath, usually around only the axon of a neuron. It is essential for the proper functioning of the nervous system. Myelin is an outgrowth of a glial cell. Schwann cells supply the myelin for peripheral neurons, whereas oligodendrocytes, specifically of the interfascicular type, axons An axon or nerve fiber is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma) in the cerebrum The cerebrum or telencephalon, together with the diencephalon, constitute the forebrain. It is the most anterior or, especially in humans, most superior region of the vertebrate central nervous system. "Telencephalon" refers to the embryonic structure, from which the mature "cerebrum" develops. The dorsal telencephalon, or. The neocortex is smooth in rodents Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing and other small mammals, whereas in primates A primate is a member of the biological order Primates (/praɪˈmeɪtiːz/ prī·mā′·tēz; Latin: "prime, first rank"), the group that contains prosimians (including lemurs, lorises, galagos and tarsiers ) and simians (monkeys and apes). With the exception of humans, who inhabit every continent on Earth,[a] most primates live in and other larger mammals it has deep grooves (sulci) and wrinkles (gyri A gyrus is a ridge on the cerebral cortex. It is generally surrounded by one or more sulci) . These folds increase the surface area of the neocortex considerably without taking up too much more volume. This has allowed primates and especially humans to evolve new functional areas of neocortex that are responsible for enhanced cognitive skills such as working memory Working memory is the executive and attentional aspect of short-term memory involved in the interim integration, processing, disposal, and retrieval of information. Working memory tasks include the active monitoring or manipulation of information or behaviors. It is a theoretical construct within cognitive psychology and neuroscience. Theories, speech, and language.

The neocortex contains two primary types of neurons, excitatory pyramidal neurons Pyramidal neurons are a type of neuron found in areas of the brain including cerebral cortex, the hippocampus, and in the amygdala. Pyramidal neurons are the primary excitation units of the mammalian prefrontal cortex and the corticospinal tract. Pyramidal neurons were first discovered and studied by Santiago Ramón y Cajal. Since then, studies on (~80% of neocortical neurons) and inhibitory interneurons An interneuron is a multipolar neuron which connects afferent neurons and efferent neurons in neural pathways. Like motor neurons, interneuron cell bodies are always located in the central nervous system (CNS) (~20%). The structure of the neocortex is relatively uniform (hence the alternative names "iso-" and "homotypic" cortex): it consists of six horizontal layers segregated principally by cell The cell is the functional basic unit of life. It was discovered by Robert Hooke and is the functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. Some organisms, such as most bacteria, are unicellular . Other organisms, such as humans, type and neuronal A neuron (pronounced /ˈnjʊərɒn/ NOOR-on, also known as a neurone or nerve cell) is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core connections. However, there are many exceptions to this uniformity; for example, the motor cortex Motor cortex is a term that describes regions of the cerebral cortex involved in the planning, control, and execution of voluntary motor functions lacks layer IV. There is some canonical circuitry within the cortex; for example, pyramidal neurons in the upper layers II and III project their axons An axon or nerve fiber is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma to other areas of neocortex, while those in the deeper layers V and VI project primarily out of the cortex, e.g. to the thalamus The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections. Its function includes relaying sensation, special sense and motor signals to the cerebral cortex, along with the regulation of, brainstem In vertebrate anatomy the brainstem is the posterior part of the brain, adjoining and structurally continuous with the spinal cord. The brain stem provides the main motor and sensory innervation to the face and neck via the cranial nerves. Though small, this is an extremely important part of the brain as the nerve connections of the motor and, and spinal cord The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system. The spinal cord extends down to the space between the first and second lumbar vertebrae; it does not extend the entire length of the vertebral column. It is around 4. Neurons in layer IV receive all of the synaptic connections In the nervous system, a synapse is a structure that permits a neuron to pass an electrical or chemical signal to another cell. The word "synapse" comes from "synaptein", which Sir Charles Scott Sherrington and colleagues coined from the Greek "syn-" and "haptein" ("to clasp") from outside the cortex (mostly from thalamus), and themselves make short-range, local connections to other cortical layers. Thus, layer IV receives all incoming sensory information and distributes it to the other layers for further processing.

The neurons of the neocortex are also arranged in vertical structures called neocortical columns A cortical column, also called hypercolumn or sometimes cortical module, 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. Neurons within a minicolumn encode similar features, whereas a hypercolumn ". 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 Sound is a travelling wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations or vision Visual perception is the ability to interpret information and surroundings from visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision . The various physiological components involved in vision are referred to collectively as the visual system, and are the focus of much research in psychology, cognitive. These columns are similar, and can be thought of as the basic repeating functional units of the neocortex. In humans, the neocortex consists of about a half-million of these columns, each of which contains approximately 60,000 neurons. However, because of inhomogeneity in columnar borders outside the visual cortex, there is still further studies needed before accepting the columnar cortex theory as fact.^{[citation needed]}

The neocortex is divided into frontal The frontal lobe is an area in the brain of mammals. It is located at the front of each cerebral hemisphere and positioned anterior to the parietal lobes and above and anterior to the temporal lobes. It is separated from the parietal lobe by the primary motor cortex, which controls voluntary movements of specific body parts associated with the, parietal The parietal lobe is a lobe in the brain. It is positioned above the occipital lobe and behind (posterior to) the frontal lobe, occipital The occipital lobe is the visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area 17, commonly called V1 . Human V1 is located on the medial side of the occipital lobe within the calcarine sulcus; the full extent of V1 often continues onto the, and temporal The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both the left and right hemi hellospheres of the brain lobes, which perform different functions. For example, the occipital lobe contains the primary visual cortex The term visual cortex refers to the primary visual cortex and extrastriate visual cortical areas such as V2, V3, V4, and V5. The primary visual cortex is anatomically equivalent to Brodmann area 17, or BA17. The extrastriate cortical areas consist of Brodmann area 18 and Brodmann area 19. There is a visual cortex for each hemisphere of the brain, and the temporal lobe contains the primary auditory cortex The primary auditory cortex is the region of the brain that is responsible for processing of auditory information. It is located on the temporal lobe, and performs the basics of hearing; pitch and volume. Further subdivisions or areas of neocortex are responsible for more specific cognitive processes. In humans, the frontal lobe The frontal lobe is an area in the brain of mammals. It is located at the front of each cerebral hemisphere and positioned anterior to the parietal lobes and above and anterior to the temporal lobes. It is separated from the parietal lobe by the primary motor cortex, which controls voluntary movements of specific body parts associated with the contains areas devoted to abilities that are enhanced in or unique to our species, such as complex language processing localized to the ventrolateral prefrontal cortex (Broca's area The production of language has been linked to the Broca’s area since Paul Pierre Broca reported impairments in two patients. They had lost the ability to speak after injury to the posterior inferior frontal gyrus of the brain. Since then, the approximate region he identified has become known as Broca’s area, and the deficit in language). In humans and other primates, social and emotional processing is localized to the orbitofrontal cortex The orbitofrontal cortex is a prefrontal cortex region in the frontal lobes in the brain which is involved in the cognitive processing of decision-making. It consists in non-human primates of the association cortex areas brodmann area 11, 12 and 13; in humans it consists of brodmann area 10, 11 and 47 Because of its functions in emotion and reward,. (See Cerebral cortex The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different composition in terms of neurons and connectivity. The human and Cerebrum The cerebrum or telencephalon, together with the diencephalon, constitute the forebrain. It is the most anterior or, especially in humans, most superior region of the vertebrate central nervous system. "Telencephalon" refers to the embryonic structure, from which the mature "cerebrum" develops. The dorsal telencephalon, or.)

Evolution

The neocortex is the newest part of the cerebral cortex The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different composition in terms of neurons and connectivity. The human to evolve (hence the prefix "neo"); the other parts of the cerebral cortex are the paleocortex The paleocortex is a layer of the cerebral cortex intermediate phylogenetically between the neocortex and archicortex 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 neocortex.

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.^[3] In a similar manner, reptiles, such as turtles, have primary sensory cortices. A consistent, alternative name has yet to be agreed upon.

Neocortex ratio

The neocortex ratio of a species is the ratio of the size of the neocortex to the rest of the brain. A high neocortex ratio is thought to correlate with a number of social variables such as group size and the complexity of social mating behaviors. (See Dunbar's number)

See also

• List of regions in the human brain
• Blue Brain, a project to produce a computer simulation of a neocortical column and eventually a whole neocortex
• Software model of the neocortex by Jeff Hawkins (http://www.numenta.com/)
• Model of the neocortex by the Brain Engineering Laboratory at Dartmouth College (http://www.dartmouth.edu/~rhg/Research4Neo.html)
• Comparative Neuroscience at Wikiversity

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. doi:10.1038/nrn1606. 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. doi:10.1002/cne.20118. PMID 15116397.
3. ^ http://www.newscientist.com/article/dn14552-mirror-test-shows-magpies-arent-so-birdbrained.html?DCMP=ILC-hmts&nsref=news4_head_dn14552

Categories: Neuroanatomy | Cerebrum

What Links Here:

Most Popular Pages:

Related 'Neo Cortex' Searches: