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Brodmann Area 4
Brodmann area 4 refers to the primary motor cortex of the human brain. It is located in the posterior portion of the frontal lobe. Brodmann area 4 is part of the precentral gyrus. The borders of this area are: the precentral sulcus in front ( anteriorly), the medial longitudinal fissure at the top ( medially), the central sulcus in back (posteriorly), and the lateral sulcus along the bottom (laterally). This area of cortex, as shown by Wilder Penfield and others, has the pattern of a homunculus. That is, the legs and trunk fold over the midline; the arms and hands are along the middle of the area shown here; and the face is near the bottom of the figure. Because Brodmann area 4 is in the same general location as primary motor cortex, the homunculus here is called the motor homunculus. The term area 4 of Brodmann-1909 refers to a cytoarchitecturally defined portion of the frontal lobe of the guenon. It is located predominantly in the precentral gyrus. Brodmann-1909 rega ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precentral Gyrus
The precentral gyrus is a prominent gyrus on the surface of the posterior frontal lobe of the brain. It is the site of the primary motor cortex that in humans is cytoarchitecturally defined as Brodmann area 4. Structure The precentral gyrus lies in front of the postcentral gyrus - mostly on the lateral (convex) side of each cerebral hemisphere - from which it is separated by the central sulcus. Its anterior border is represented by the precentral sulcus, while inferiorly it borders to the lateral sulcus (Sylvian fissure). Medially, it is contiguous with the paracentral lobule. The internal pyramidal layer (layer V) of the precentral cortex contains giant (70-100 micrometers) pyramidal neurons called Betz cells, which send long axons to the contralateral motor nuclei of the cranial nerves and to the lower motor neurons in the ventral horn of the spinal cord. These axons form the corticospinal tract. The Betz cells along with their long axons are referred to as upper motor n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homunculus
A homunculus ( , , ; "little person") is a representation of a small human being, originally depicted as small statues made out of clay. Popularized in sixteenth-century alchemy and nineteenth-century fiction, it has historically referred to the creation of a miniature, fully formed human. The concept has roots in preformationism as well as earlier folklore and alchemic traditions. The term lends its name to the cortical homunculus, an image of a person with the size of the body parts distorted to represent how much area of the cerebral cortex of the brain is devoted to it. History Alchemy The homunculus first appears by name in alchemical writings attributed to Paracelsus (1493–1541). ''De natura rerum'' (1537) outlines his method for creating homunculi: Comparisons have been made with several similar concepts in the writings of earlier alchemists. Although the actual word "homunculus" was never used, Carl Jung believed that the concept first appeared in the ''Visions of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 * Medulla oblongata **Medullary pyramids **Arcuate nucleus **Olivary body ***Inferior olivary nucleus **Rostral ventrolateral medulla **Caudal ventrolateral medulla **Solitary nucleus (Nucleus of the solitary tract) **Respiratory center- Respiratory groups ***Dorsal respiratory group ***Ventral respiratory group or Apneustic centre ****Pre-Bötzinger complex ****Botzinger complex ****Retrotrapezoid nucleus ****Nucleus retrofacialis ****Nucleus retroambiguus ****Nucleus para-ambiguus **Paramedian reticular nucleus **Gigantocellular reticular nucleus **Parafacial zone **Cuneate nucleus ** Gracile nucleus ** Perihypoglossal nuclei *** Intercalated nucleus *** Prepositus nucleus *** Sublingual nucleus **Area postrema **Medullary cranial nerve nucl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brodmann Area
A Brodmann area is a region of the cerebral cortex, in the human or other primate brain, defined by its cytoarchitecture, or histological structure and organization of cells. History Brodmann areas were originally defined and numbered by the German anatomist Korbinian Brodmann based on the cytoarchitectural organization of neurons he observed in the cerebral cortex using the Nissl method of cell staining. Brodmann published his maps of cortical areas in humans, monkeys, and other species in 1909, along with many other findings and observations regarding the general cell types and laminar organization of the mammalian cortex. The same Brodmann area number in different species does not necessarily indicate homologous areas. A similar, but more detailed cortical map was published by Constantin von Economo and Georg N. Koskinas in 1925. Present importance Brodmann areas have been discussed, debated, refined, and renamed exhaustively for nearly a century and remain the most wid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White Matter
White matter refers to areas of the central nervous system (CNS) that are mainly made up of myelinated axons, also called tracts. Long thought to be passive tissue, white matter affects learning and brain functions, modulating the distribution of action potentials, acting as a relay and coordinating communication between different brain regions. White matter is named for its relatively light appearance resulting from the lipid content of myelin. However, the 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 in prepared specimens is due to its usual preservation in formaldehyde. Structure White matter White matter is composed of bundles, which connect various grey matter areas (the locations of nerve cell bodies) of the brain to each other, and carry nerve impulses between neurons. Myelin acts as an insulator, which allows electrical signals to jump, rather than c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiform Layer
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting of allocortex. It is separated into two cortices, by the longitudinal fissure that divides the cerebrum into the left and right cerebral hemispheres. The two hemispheres are joined beneath the cortex by the corpus callosum. The cerebral cortex is the largest site of neural integration in the central nervous system. It plays a key role in attention, perception, awareness, thought, memory, language, and consciousness. The cerebral cortex is part of the brain responsible for cognition. In most mammals, apart from small mammals that have small brains, the cerebral cortex is folded, providing a greater surface area in the confined volume of the cranium. Apart from minimising brain and cranial volume, cortical folding is crucial for the brai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Granular Layer (cerebral Cortex)
The internal granular layer of the cortex, also commonly referred to as the granular layer of the cortex, is the layer IV in the subdivision of the mammalian cortex into 6 layers. The adjective internal is used in opposition to the external granular layer of the cortex, the term granular refers to the granule cells found here. This layer receives the afferent connections from the thalamus and from other cortical regions and sends connections to the other layers. The line of Gennari The line of Gennari (also called the "band" or "stria" of Gennari) is a band of myelinated axons that runs parallel to the surface of the cerebral cortex on the banks of the calcarine fissure in the occipital lobe. This formation is visible to the ... (occipital stripe) is also present in this layer. Cerebral cortex {{neuroanatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyramidal Layer
A pyramid (from el, πυραμίς ') is a structure whose outer surfaces are triangular and converge to a single step at the top, making the shape roughly a pyramid in the geometric sense. The base of a pyramid can be trilateral, quadrilateral, or of any polygon shape. As such, a pyramid has at least three outer triangular surfaces (at least four faces including the base). The square pyramid, with a square base and four triangular outer surfaces, is a common version. A pyramid's design, with the majority of the weight closer to the ground and with the pyramidion at the apex, means that less material higher up on the pyramid will be pushing down from above. This distribution of weight allowed early civilizations to create stable monumental structures. Civilizations in many parts of the world have built pyramids. The largest pyramid by volume is the Great Pyramid of Cholula, in the Mexican state of Puebla. For thousands of years, the largest structures on Earth were pyrami ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyramidal Cell
Pyramidal cells, or pyramidal neurons, are a type of multipolar neuron found in areas of the brain including the cerebral cortex, the hippocampus, and the amygdala. Pyramidal neurons are the primary excitation units of the mammalian prefrontal cortex and the corticospinal tract. Pyramidal neurons are also one of two cell types where the characteristic sign, Negri bodies, are found in post-mortem rabies infection. Pyramidal neurons were first discovered and studied by Santiago Ramón y Cajal. Since then, studies on pyramidal neurons have focused on topics ranging from neuroplasticity to cognition. Structure File:GFPneuron.png, Pyramidal neuron visualized by green fluorescent protein (gfp) File:Hippocampal-pyramidal-cell.png, A hippocampal pyramidal cell One of the main structural features of the pyramidal neuron is the conic shaped soma, or cell body, after which the neuron is named. Other key structural features of the pyramidal cell are a single axon, a large apical dendrite, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Korbinian Brodmann
Korbinian Brodmann (17 November 1868 – 22 August 1918) was a German neurologist who became famous for mapping the cerebral cortex and defining 52 distinct regions, known as Brodmann areas, based on their cytoarchitectonic (histological) characteristics. Life and career Brodmann was born in Liggersdorf, Province of Hohenzollern. He studied medicine in Munich, Würzburg, Berlin, and Freiburg, where he received his medical diploma in 1895. Subsequently he studied at the Medical School in the University of Lausanne in Switzerland, and then worked in the University Clinic in Munich. He received a doctor of medicine degree from the University of Leipzig in 1898, with a thesis on chronic ependymal sclerosis. From 1900 to 1901, Brodmann also worked in the Psychiatric Clinic at the University of Jena, with Ludwig Binswanger, and in the Municipal Mental Asylum in Frankfurt. There, he met Alois Alzheimer, who was influential in his decision to pursue basic neuroscience research. Fol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guenon
The guenons (, ) are Old World monkeys of the genus ''Cercopithecus'' (). Not all members of this genus have the word "guenon" in their common names; also, because of changes in scientific classification, some monkeys in other genera may have common names that include the word "guenon". Nonetheless, the use of the term guenon for monkeys of this genus is widely accepted. All members of the genus are endemic to sub-Saharan Africa, and most are forest monkeys. Many of the species are quite local in their ranges, and some have even more local subspecies. Many are threatened or endangered because of habitat loss. The species currently placed in the genus ''Chlorocebus'', such as vervet monkeys and green monkeys, were formerly considered as a single species in this genus, ''Cercopithecus aethiops''. In the English language, the word "guenon" is apparently of French origin. In French, ''guenon'' was the common name for all species and individuals, both males and females, from the gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytoarchitecture
Cytoarchitecture (Greek '' κύτος''= "cell" + '' ἀρχιτεκτονική''= "architecture"), also known as cytoarchitectonics, is the study of the cellular composition of the central nervous system's tissues under the microscope. Cytoarchitectonics is one of the ways to parse the brain, by obtaining sections of the brain using a microtome and staining them with chemical agents which reveal where different neurons are located. The study of the parcellation of ''nerve fibers'' (primarily axons) into layers forms the subject of myeloarchitectonics ( History of the cerebral cytoarchitecture Defining cerebral cytoarchitecture began with the advent of —the science of slicing a ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
