1.
Operculum (brain)
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In human brain anatomy, an operculum, may refer to the frontal, temporal, or parietal operculum, which together cover the insula as the opercula of insula. It can also refer to the operculum, part of the occipital lobe. The insular lobe is a portion of the cortex that has invaginated to lie deep within the lateral sulcus. It sits like an island almost surrounded by the groove of the sulcus and covered over. A part of the lobe, the frontoparietal operculum, covers the upper part of the insular lobe from the front to the back. The opercula lie on the precentral and postcentral gyri, the part of the parietal operculum that forms the ceiling of the lateral sulcus functions as the secondary somatosensory cortex. Normally, the insular opercula begin to develop between the 20th and the 22nd weeks of pregnancy. At weeks 14 to 16 of fetal development, the insula begins to invaginate from the surface of the cerebrum of the brain, until at full term. Opinions differ on whether Albert Einstein’s brain possessed parietal opercula, Falk, et al. claim that the brain actually did have parietal opercula, while Witelson et al. claim that it did not. Einsteins lower parietal lobe was 15% larger than average, figure 9 of Falk 2013 is a photograph of Einsteins right insula after removal of the operculum. Sulcus lateralis Circular sulcus of insula Dorland, Falk D, Lepore FE, Noe A. The cerebral cortex of Albert Einstein, a description and preliminary analysis of unpublished photographs
2.
Cerebral cortex
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The cerebral cortex is the outer layer of neural tissue of the cerebrum of the brain, in humans and other mammals. It is separated into two cortices, by the 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 plays a key role in memory, attention, perception, awareness, thought, language, and consciousness. In large mammals, the cortex is folded, giving a much greater surface area in the confined volume of the skull. A fold or ridge in the cortex is termed a gyrus, in the human brain more than two-thirds of the cerebral cortex is buried in the sulci. The human cerebral cortex is 2 to 4 millimetres thick, the cerebral cortex is composed of gray matter, consisting mainly of cell bodies and capillaries. It contrasts with the white matter, consisting mainly of the white myelinated sheaths of neuronal axons. The most recent part of the cortex to develop in the evolutionary history of mammals is the neocortex. Neurons in various layers connect vertically to form small microcircuits, called cortical columns, Different neocortical regions known as Brodmann areas are distinguished by variations in their cytoarchitectonics and functional roles in sensation, cognition and behavior. The different cortical layers each contain a distribution of neuronal cell types. There are direct connections between different cortical areas and indirect connections via the thalamus, for example, one of the clearest examples of cortical layering is the stria of Gennari in the primary visual cortex. This is a band of tissue that can be observed with the naked eye in the fundus of the calcarine sulcus of the occipital lobe. The Stria of Gennari is composed of axons bringing visual information from the thalamus into layer four of the visual cortex, during development Cajal-Retzius and subpial granular layer cells are present in this layer. Also, some spiny stellate cells can be found here, inputs to the apical tufts are thought to be crucial for the ‘‘feedback’’ interactions in the cerebral cortex involved in associative learning and attention. Layer II, the granular layer, contains small pyramidal neurons. Layer V, the internal pyramidal layer, contains large pyramidal neurons which give rise to axons leaving the cortex and that is, layer VI neurons from one cortical column connect with thalamus neurons that provide input to the same cortical column. These connections are both excitatory and inhibitory, neurons send excitatory fibers to neurons in the thalamus and also send collaterals to the thalamic reticular nucleus that inhibit these same thalamus neurons or ones adjacent to them. One theory is that because the output is reduced by cholinergic input to the cerebral cortex
3.
Brain
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The brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. The brain is located in the head, usually close to the organs for senses such as vision. The brain is the most complex organ in a vertebrates body, in a human, the cerebral cortex contains approximately 15–33 billion neurons, each connected by synapses to several thousand other neurons. Physiologically, the function of the brain is to exert centralized control over the other organs of the body, the brain acts on the rest of the body both by generating patterns of muscle activity and by driving the secretion of chemicals called hormones. This centralized control allows rapid and coordinated responses to changes in the environment, the operations of individual brain cells are now understood in considerable detail but the way they cooperate in ensembles of millions is yet to be solved. This article compares the properties of brains across the range of animal species. It deals with the human brain insofar as it shares the properties of other brains, the ways in which the human brain differs from other brains are covered in the human brain article. Several topics that might be covered here are instead covered there because more can be said about them in a human context. The most important is brain disease and the effects of brain damage, the shape and size of the brain varies greatly between species, and identifying common features is often difficult. Nevertheless, there are a number of principles of architecture that apply across a wide range of species. Some aspects of structure are common to almost the entire range of animal species, others distinguish advanced brains from more primitive ones. The simplest way to gain information about brain anatomy is by visual inspection, Brain tissue in its natural state is too soft to work with, but it can be hardened by immersion in alcohol or other fixatives, and then sliced apart for examination of the interior. Visually, the interior of the consists of areas of so-called grey matter, with a dark color, separated by areas of white matter. Further information can be gained by staining slices of tissue with a variety of chemicals that bring out areas where specific types of molecules are present in high concentrations. It is also possible to examine the microstructure of brain tissue using a microscope, the brains of all species are composed primarily of two broad classes of cells, neurons and glial cells. Glial cells come in types, and perform a number of critical functions, including structural support, metabolic support, insulation. Neurons, however, are considered the most important cells in the brain. The property that makes neurons unique is their ability to send signals to target cells over long distances
4.
Artery
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Arteries are blood vessels that carry blood away from the heart. While most arteries carry oxygenated blood, there are two exceptions to this, the pulmonary and the umbilical arteries, the effective arterial blood volume is that extracellular fluid which fills the arterial system. The anatomy of arteries can be separated into gross anatomy, at the level, and microscopic anatomy. The outermost layer is known as the tunica externa, also known as tunica adventitia, inside this layer is the tunica media, or media, which is made up of smooth muscle cells and elastic tissue. The innermost layer, which is in contact with the flow of blood, is the tunica intima. This layer is made up of endothelial cells. The hollow internal cavity in which the flows is called the lumen. Arterial formation begins when endothelial cells begin to express specific genes. Arteries form part of the circulatory system and they carry blood that is oxygenated after it has been pumped from the heart. Arteries also aid the heart in pumping blood, arteries carry oxygenated blood away from the heart to the tissues, except for pulmonary arteries, which carry blood to the lungs for oxygenation. Veins and pulmonary veins carry deoxygenated blood. )The pulmonary artery carries blood from the heart to the lungs and it is unique because the blood in it is not oxygenated, as it has not yet passed through the lungs. The other unique artery is the artery, which carries deoxygenated blood from a fetus to its mother. Arteries have a blood pressure than other parts of the circulatory system. The pressure in arteries varies during the cardiac cycle and it is highest when the heart contracts and lowest when heart relaxes. The variation in pressure produces a pulse, which can be felt in different areas of the body, arterioles have the greatest collective influence on both local blood flow and on overall blood pressure. They are the primary adjustable nozzles in the system, across which the greatest pressure drop occurs. The larger arteries are generally elastic and the smaller ones tend to be muscular, systemic arteries deliver blood to the arterioles, and then to the capillaries, where nutrients and gases are exchanged. After travelling from the aorta, blood travels through peripheral arteries into smaller arteries called arterioles, arterioles help in regulating blood pressure by the variable contraction of the smooth muscle of their walls, and deliver blood to the capillaries
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Middle cerebral artery
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The middle cerebral artery is one of the three major paired arteries that supply blood to the cerebrum. The MCA arises from the carotid and continues into the lateral sulcus where it then branches. It also supplies blood to the temporal lobes and the insular cortices. The MCAs are not considered a part of the Circle of Willis, the middle cerebral artery can be classified into 4 parts, M1, The sphenoidal segment, so named due to its origin and loose lateral tracking of the sphenoid bone. Although known also as the segment, this may be misleading since the segment may descend, remain flat. The M1 segment perforates the brain with numerous anterolateral central arteries, M2, Extending anteriorly on the insula, this segment in known as the insular segment. It is also known as the Sylvian segment when the segments are included. The MCA branches may bifurcate or sometimes trifurcate into trunks in this segment which then extend into branches that terminate towards the cortex, M3, The opercular segments and extends laterally exteriorly from the insula towards the cortex. This segment is sometimes grouped as part of M2, m4, These finer terminal or cortical segments irrigate the cortex. They begin at the external of the Sylvian fissure and extend distally away on the cortex of the brain, the M2 and M3 segments may each split into 2 or 3 main trunks with an upper trunk, lower trunk and occasionally a middle trunk. Bifurcations and trifurcations occurs in 50% and 25% of the cases respectively, other cases include duplication of the MCA at the internal carotid artery or an accessory MCA which arise not from the ICA but as a branch from the anterior cerebral artery. The branches of the MCA can be described by the areas that they irrigate, lateral frontobasal, This artery branches out anteriorly, superiorly and laterally to vascularize the inferior frontal gyrus. The arteries fan superiorly over the pars triangularis and vascularize the inferior, near the superior frontal gyrus these arteries anastamose with branches from the pericallosal artery of the anterior cerebral artery. This artery branches once or twice and is relatively invariant across anatomies, rolandic arteries, The artery extends out and exits from the central portion of the operculum then passes inside the central sulcus. This artery bifurcates in 72% of individuals and irrigates the posterior pre-central gyrus, Anterior parietal, This artery usually originates from the anterior or middle MCA trunk. In some cases it branches from the artery or from the posterior parietal artery. It extends the length of interparietal sulcus and descends slightly posteriorly, posterior parietal, Emerges from the posterior end of the Sylvian fissure and extends first posteriorly, and then anteriorly along the posterior of the parietal lobe. It also branches to the supramarginal gyrus, angular, The angular artery is a significant terminal branch of the anterior or middle trunk of the MCA
6.
Latin
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Latin is a classical language belonging to the Italic branch of the Indo-European languages. The Latin alphabet is derived from the Etruscan and Greek alphabets, Latin was originally spoken in Latium, in the Italian Peninsula. Through the power of the Roman Republic, it became the dominant language, Vulgar Latin developed into the Romance languages, such as Italian, Portuguese, Spanish, French, and Romanian. Latin, Italian and French have contributed many words to the English language, Latin and Ancient Greek roots are used in theology, biology, and medicine. By the late Roman Republic, Old Latin had been standardised into Classical Latin, Vulgar Latin was the colloquial form spoken during the same time and attested in inscriptions and the works of comic playwrights like Plautus and Terence. Late Latin is the language from the 3rd century. Later, Early Modern Latin and Modern Latin evolved, Latin was used as the language of international communication, scholarship, and science until well into the 18th century, when it began to be supplanted by vernaculars. Ecclesiastical Latin remains the language of the Holy See and the Roman Rite of the Catholic Church. Today, many students, scholars and members of the Catholic clergy speak Latin fluently and it is taught in primary, secondary and postsecondary educational institutions around the world. The language has been passed down through various forms, some inscriptions have been published in an internationally agreed, monumental, multivolume series, the Corpus Inscriptionum Latinarum. Authors and publishers vary, but the format is about the same, volumes detailing inscriptions with a critical apparatus stating the provenance, the reading and interpretation of these inscriptions is the subject matter of the field of epigraphy. The works of several hundred ancient authors who wrote in Latin have survived in whole or in part and they are in part the subject matter of the field of classics. The Cat in the Hat, and a book of fairy tales, additional resources include phrasebooks and resources for rendering everyday phrases and concepts into Latin, such as Meissners Latin Phrasebook. The Latin influence in English has been significant at all stages of its insular development. From the 16th to the 18th centuries, English writers cobbled together huge numbers of new words from Latin and Greek words, dubbed inkhorn terms, as if they had spilled from a pot of ink. Many of these words were used once by the author and then forgotten, many of the most common polysyllabic English words are of Latin origin through the medium of Old French. Romance words make respectively 59%, 20% and 14% of English, German and those figures can rise dramatically when only non-compound and non-derived words are included. Accordingly, Romance words make roughly 35% of the vocabulary of Dutch, Roman engineering had the same effect on scientific terminology as a whole
7.
NeuroNames
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NeuroNames is an integrated nomenclature for structures in the brain and spinal cord of the four species most studied by neuroscientists, human, macaque, rat and mouse. It offers a standard, controlled vocabulary of common names for structures, terms in the standard vocabulary have been selected for ease of pronunciation, mnemonic value, and frequency of use in recent neuroscientific publications. Structures and their relations to each other are defined in terms of the standard vocabulary, currently NeuroNames contains standard names, synonyms and definitions of some 2,500 neuroanatomical entities. The nomenclature is maintained by the University of Washington and is the component of a tool called BrainInfo. BrainInfo helps one identify structures in the brain, Information can be accessed by any of some 16,000 synonyms in eight languages. NeuroNames is a vocabulary of the Metathesaurus of the Unified Medical Language System. It is described in depth in the three scientific articles, D. M. Bowden & R. F. Martin. D. M. Bowden & M. F. Dubach, D. M. Bowden, E. Song, J. Kosheleva, M. F. Dubach. NeuroNames, An Ontology for the BrainInfo Portal to Neuroscience on the Web, neuroLex Neuroscience Information Framework Talairach coordinates Overview of NeuroNames BrainInfo NeuroNames Direct Link
8.
NeuroLex
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NeuroLex is a dynamic lexicon of neuroscience concepts. It is a structured as a wiki, using Semantic MediaWiki. NeuroLex is supported by the Neuroscience Information Framework project, one of the big roadblocks to data integration in neuroscience is the inconsistent use of terminology in databases and other resources like the literature. When one uses the terms to mean different things, one cannot easily ask questions that span across multiple resources. For example, if three databases have information about what genes are expressed in cortex, but they all use different definitions of cerebral cortex, the NIF enables discovery and access to public research data and tools worldwide through an open source, networked environment. The Framework is an inventory of neuroscience databases, annotated and integrated with a unified system of biomedical terminology. NIF supports concept-based queries across multiple scales of biological structure and multiple levels of function, making it easier to search for. As part of the NIF, an interface to many different sources of neuroscience information. To make this more effective, the NIF is constructing ontologies to help organize neuroscience concepts into category hierarchies. This allows users to more effective searches and also to organize. But an important adjunct to this activity is to define all of the terms that are used to describe data, e. g. anatomical terms, techniques. The initial entries in the NeuroLex were built from the NIFSTD ontologies which subsumed an earlier vocabulary BIRNLex and it currently contains concepts that span gross anatomy, cells of the nervous system, subcellular structures, diseases, functions and techniques. NIF is soliciting community input to add content and correct what is there. The NIFSTD and BIRNLex vocabularies, building comprehensive ontologies for neuroscience, archived from the original on February 12,2009. The neuroscience information framework, a data and knowledge environment for neuroscience, Gardner D, Goldberg DH, Grafstein B, Robert A, Gardner EP. Terminology for neuroscience data discovery, multi-tree syntax and investigator-derived semantics. Gupta A, Bug W, Marenco L, Qian X, Condit C, Rangarajan A, Müller HM, Miller PL, Sanders B, Grethe JS, Astakhov V, Shepherd G, Sternberg PW, federated access to heterogeneous information resources in the Neuroscience Information Framework. Halavi M, Polavaram S, Donohue DE, Hamilton G, Hoyt J, Smith KP, neuroMorpho. Org implementation of digital neuroscience, dense coverage and integration with the NIF
9.
Glossary of neuroanatomy
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This article attempts to provide definitions to a number of anatomical terminology, definitions and abbreviations, pertinent to the description of the Central Nervous System, particularly in humans. It aims to further information to the description of orientation in neuroanatomy. To understand the terms used for anatomical localisation, consider an animal with a straight CNS, in such animals the terms rostral, caudal, ventral and dorsal mean respectively towards the rostrum, towards the tail, towards the belly and towards the back. For a full discussion of terms, see anatomical terms of location. For many purposes of description, positions and directions are relative to the standard anatomical planes and axes. Such reference to the planes and axes is called the stereotactic approach. However, in humans and most other primates the axis of the CNS is bent and these are shown in the accompanying illustrations and annotations. In particular the anatomical planes and axes that apply to most vertebrate nervous systems need considerable modification before they can be of use in describing the human brain. For example in reference to the brain, rostral still means towards the face, or at any rate. However, in the brain caudal means not towards the tail, alternative terms for this rostro-caudal axis of the brain include medial or antero-posterior axis. Dorsal means in the direction away from the spinal cord i. e. in the direction of the roof of the cranial cavity, ventral means downwards towards floor of the cranial cavity and thence to the body. They lie on the superior-inferior or Dorsoventral axis, the third axis passes through the ears, and is called the left-right, or lateral axis. These three axes of the human brain match the three planes within which they lie, even though the terms for the planes have not been changed from the terms for the bodily planes. The most commonly used reference planes are, Axial, the plane that is horizontal and it contains the lateral and the medial axes of the brain. Coronal, a plane that passes through both ears, and contains the lateral and dorsoventral axes. Sagittal, a plane that passes from between the nostrils, and between the cerebral hemispheres, dividing the brain into left and right halves. It contains the dorsoventral and medial axes of the brain, a parasagittal plane is any plane parallel to the sagittal plane. Afferent An afferent nerve fiber is a fibre originating at the present point, for example a striatal afferent is an afferent originating at the striatum
10.
Brain hemisphere
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The vertebrate cerebrum is formed by two cerebral hemispheres that are separated by a groove, the longitudinal fissure. The brain can thus be described as being divided into left, each of these hemispheres has an outer layer of grey matter, the cerebral cortex, that is supported by an inner layer of white matter. In eutherian mammals, the hemispheres are linked by the corpus callosum, smaller commissures, including the anterior commissure, the posterior commissure and the fornix, also join the hemispheres and these are also present in other vertebrates. These commissures transfer information between the two hemispheres to coordinate localized functions, there are three poles of the hemispheres named as the occcipital pole, the frontal pole, and at the front of the temporal lobe the temporal pole. If the upper part of either hemisphere be removed, at a level about 1.25 cm, each labium is part of the cingulate gyrus already described, and the slit-like interval between it and the upper surface of the corpus callosum is termed the callosal sulcus. If the hemispheres be sliced off to a level with the surface of the corpus callosum. The large expanse of medullary matter now exposed, surrounded by the margin of gray substance, is called the centrum ovale majus. The blood supply to the centrum ovale is from the middle cerebral artery. The cortical branches of this artery descend to provide blood to the centrum ovale, the cerebral hemispheres are derived from the telencephalon. They arise five weeks after conception as bilateral invaginations of the walls, the hemispheres grow round in a C-shape and then back again, pulling all structures internal to the hemispheres with them. The intraventricular foramina allows communication with the lateral ventricles, the choroid plexus is formed from ependymal cells and vascular mesenchyme. Broad generalizations are often made in popular psychology about certain functions being lateralized and these claims are often inaccurate, as most brain functions are actually distributed across both hemispheres. Most scientific evidence for asymmetry relates to low-level perceptual functions rather than the higher-level functions popularly discussed, the best example of an established lateralization is that of Brocas and Wernickes Areas where both are often found exclusively on the left hemisphere. These areas frequently correspond to handedness however, meaning the localization of these areas is found on the hemisphere opposite to the dominant hand. Function lateralization such as semantics, prosodic, intonation, accentuation, prosody, etc has since been called into question, perceptual information is processed in both hemispheres, but is laterally partitioned, information from each side of the body is sent to the opposite hemisphere. Similarly, motor control signals sent out to the body also come from the hemisphere on the opposite side, thus, hand preference is also related to hemisphere lateralization. In some aspects, the hemispheres are asymmetrical, one side is slightly bigger, there are higher levels of the neurotransmitter norepinephrine on the right and higher levels of dopamine on the left. There is more white matter on right and more grey matter on the left, linear reasoning functions of language such as grammar and word production are often lateralized to the left hemisphere of the brain
11.
Mammal
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Mammals are any vertebrates within the class Mammalia, a clade of endothermic amniotes distinguished from reptiles by the possession of a neocortex, hair, three middle ear bones and mammary glands. All female mammals nurse their young with milk, secreted from the mammary glands, Mammals include the largest animals on the planet, the great whales. The basic body type is a quadruped, but some mammals are adapted for life at sea, in the air, in trees. The largest group of mammals, the placentals, have a placenta, Mammals range in size from the 30–40 mm bumblebee bat to the 30-meter blue whale. With the exception of the five species of monotreme, all modern mammals give birth to live young, most mammals, including the six most species-rich orders, belong to the placental group. The largest orders are the rodents, bats and Soricomorpha, the next three biggest orders, depending on the biological classification scheme used, are the Primates, the Cetartiodactyla, and the Carnivora. Living mammals are divided into the Yinotheria and Theriiformes There are around 5450 species of mammal, in some classifications, extant mammals are divided into two subclasses, the Prototheria, that is, the order Monotremata, and the Theria, or the infraclasses Metatheria and Eutheria. The marsupials constitute the group of the Metatheria, and include all living metatherians as well as many extinct ones. Much of the changes reflect the advances of cladistic analysis and molecular genetics, findings from molecular genetics, for example, have prompted adopting new groups, such as the Afrotheria, and abandoning traditional groups, such as the Insectivora. The mammals represent the only living Synapsida, which together with the Sauropsida form the Amniota clade, the early synapsid mammalian ancestors were sphenacodont pelycosaurs, a group that produced the non-mammalian Dimetrodon. At the end of the Carboniferous period, this group diverged from the line that led to todays reptiles. Some mammals are intelligent, with some possessing large brains, self-awareness, Mammals can communicate and vocalize in several different ways, including the production of ultrasound, scent-marking, alarm signals, singing, and echolocation. Mammals can organize themselves into fission-fusion societies, harems, and hierarchies, most mammals are polygynous, but some can be monogamous or polyandrous. They provided, and continue to provide, power for transport and agriculture, as well as commodities such as meat, dairy products, wool. Mammals are hunted or raced for sport, and are used as model organisms in science, Mammals have been depicted in art since Palaeolithic times, and appear in literature, film, mythology, and religion. Defaunation of mammals is primarily driven by anthropogenic factors, such as poaching and habitat destruction, Mammal classification has been through several iterations since Carl Linnaeus initially defined the class. No classification system is accepted, McKenna & Bell and Wilson & Reader provide useful recent compendiums. Though field work gradually made Simpsons classification outdated, it remains the closest thing to a classification of mammals
12.
Lateral sulcus
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The lateral sulcus is one of the most prominent structures of the human brain. The lateral sulcus divides both the frontal lobe and parietal lobe above from the temporal lobe below and it is in both hemispheres of the brain but is longer in the left hemisphere in most people. The lateral sulcus is one of the earliest-developing sulci of the human brain and it first appears around the fourteenth gestational week. The lateral sulcus has a number of side branches, two of the most prominent and most regularly found are the ascending ramus and the horizontal ramus of the lateral fissure, which subdivide the inferior frontal gyrus. The lateral sulcus also contains the transverse temporal gyri, which are part of the primary, partly due to a phenomenon called Yakovlevian torque, the lateral sulcus is often longer and less curved on the left hemisphere than on the right. It is also located near Sylvian Point, the area lying around the Sylvian fissure is often referred to as the perisylvian cortex. The human secondary somatosensory cortex is a region of cortex in the parietal operculum on the ceiling of the lateral sulcus. Its first description is taken to be in 1641 by Caspar Bartholin who attributed its discovery to Franciscus Sylvius. Bartolini Institutiones Anatomicae where it is noted that F. S and it has been suggested that since Caspar Bartholin died in 1629 and Franciscus Sylvius only started medicine in 1632 that these words are either by his son Thomas Bartholin or Franciscus Sylvius. In 1663 in his Disputationem Medicarum, Franciscus Sylvius described the lateral fissure and it runs posteriorly above the temples as far as the roots of the brain stem. It divides the cerebrum into an upper, larger part and a lower, smaller part, pop musician David Bowie referred to depth psychologist Carl Jung as. crashing out with Sylvian in his lyrics to Drive In Saturday released on his 1973 album Aladdin Sane. The peri-sylvian aphasias sylvian fissure http, //www. uams. edu/radiology/education/residency/diagnostic/pdf/sylvian_cistern_RSNA2003. pdf
13.
Consciousness
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Consciousness is the state or quality of awareness, or, of being aware of an external object or something within oneself. Despite the difficulty in definition, many believe that there is a broadly shared underlying intuition about what consciousness is. Western philosophers, since the time of Descartes and Locke, have struggled to comprehend the nature of consciousness, the majority of experimental studies assess consciousness in humans by asking subjects for a verbal report of their experiences. The origin of the concept of consciousness is often attributed to John Lockes Essay Concerning Human Understanding. Locke defined consciousness as the perception of what passes in a mans own mind and his essay influenced the 18th-century view of consciousness, and his definition appeared in Samuel Johnsons celebrated Dictionary. Consciousness is also defined in the 1753 volume of Diderot and dAlemberts Encyclopédie, the earliest English language uses of conscious and consciousness date back, however, to the 1500s. This phrase had the meaning of knowing that one knows. In its earliest uses in the 1500s, the English word conscious retained the meaning of the Latin conscius. For example, Thomas Hobbes in Leviathan wrote, Where two, or more men, know of one and the fact, they are said to be Conscious of it one to another. The Latin phrase conscius sibi, whose meaning was more related to the current concept of consciousness, was rendered in English as conscious to oneself or conscious unto oneself. For example, Archbishop Ussher wrote in 1613 of being so conscious unto myself of my great weakness, Lockes definition from 1690 illustrates that a gradual shift in meaning had taken place. A related word was conscientia, which primarily means moral conscience, in the literal sense, conscientia means knowledge-with, that is, shared knowledge. The word first appears in Latin juridical texts by such as Cicero. Here, conscientia is the knowledge that a witness has of the deed of someone else, rené Descartes is generally taken to be the first philosopher to use conscientia in a way that does not fit this traditional meaning. Descartes used conscientia the way modern speakers would use conscience, in Search after Truth he says conscience or internal testimony. The dictionary meaning of the word consciousness extends through several centuries, B. inward awareness of an external object, state, or fact. The philosophy of mind has given rise to many stances regarding consciousness, something within ones mind is introspectively conscious just in case one introspects it. Introspection is often thought to deliver ones primary knowledge of ones mental life, an experience or other mental entity is phenomenally conscious just in case there is something it is like for one to have it
14.
Emotion
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Emotion, generally speaking, is any relatively brief conscious experience characterized by intense mental activity and a high degree of pleasure or displeasure. Scientific discourse has drifted to other meanings and there is no consensus on a definition, Emotion is often intertwined with mood, temperament, personality, disposition, and motivation. In some theories, cognition is an important aspect of emotion and those acting primarily on the emotions they are feeling may seem as if they are not thinking, but mental processes are still essential, particularly in the interpretation of events. For example, the realization of our believing that we are in a dangerous situation, other theories, however, claim that emotion is separate from and can precede cognition. According to some theories, they are states of feeling that result in physical and psychological changes that influence our behavior, the physiology of emotion is closely linked to arousal of the nervous system with various states and strengths of arousal relating, apparently, to particular emotions. Emotion is also linked to behavioral tendency, extroverted people are more likely to be social and express their emotions, while introverted people are more likely to be more socially withdrawn and conceal their emotions. Emotion is often the force behind motivation, positive or negative. Nor is the emotion an entity that causes these components, Emotions involve different components, such as subjective experience, cognitive processes, expressive behavior, psychophysiological changes, and instrumental behavior. More recently, emotion is said to consist of all the components, the different components of emotion are categorized somewhat differently depending on the academic discipline. In psychology and philosophy, emotion typically includes a subjective, conscious experience characterized primarily by psychophysiological expressions, biological reactions, a similar multicomponential description of emotion is found in sociology. For example, Peggy Thoits described emotions as involving physiological components, cultural or emotional labels, expressive body actions, the numerous theories that attempt to explain the origin, neurobiology, experience, and function of emotions have only fostered more intense research on this topic. Current areas of research in the concept of emotion include the development of materials that stimulate, in addition PET scans and fMRI scans help study the affective processes in the brain. Emotions can be defined as a positive or negative experience that is associated with a pattern of physiological activity. Emotions produce different physiological, behavioral and cognitive changes, the original role of emotions was to motivate adaptive behaviors that in the past would have contributed to the survival of humans. Emotions are responses to significant internal and external events, the word emotion dates back to 1579, when it was adapted from the French word émouvoir, which means to stir up. The term emotion was introduced into academic discussion to replace passion, according to one dictionary, the earliest precursors of the word likely dates back to the very origins of language. The modern word emotion is heterogeneous In some uses of the word, on the other hand, emotion can be used to refer to states that are mild and to states that are not directed at anything. One line of research looks at the meaning of the word emotion in everyday language
15.
Homeostasis
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Each of these variables is controlled by a separate “homeostat”, which, together, maintain life. The concept was described by French physiologist Claude Bernard in 1865, the term cybernetics is applied to technological control systems such as thermostats, which function as homeostats, but is often defined much more broadly than the biological term homeostasis. The word homeostasis uses combining forms of homeo- and -stasis, New Latin from Greek, ὅμοιος homoios, similar and στάσις stasis, standing still, yielding the idea of staying the same. The conceptual origins of homeostasis reach back to the ancient Greek concepts of balance, harmony, equilibrium, following these hypotheses, Hippocrates compared health to the harmonious balance of the elements, and illness and disease to the systematic disharmony of these elements. Cannon published an extrapolation from Bernards 1865 work naming his theory homeostasis, Cannon further posited that threats to homeostasis might originate from the external environment or the internal environment, and could be physical or psychological, as in emotional distress. Cannon identified these negative feedback systems and emphasized that, regardless of the nature of the threat to homeostasis, the metabolic processes of all living organisms can only take place in very specific physical and chemical environments. The conditions vary with each organism, and with whether the chemical processes take place inside the cell or in the bathing the cells in multicellular creatures. However, a great many other homeostats, encompassing many aspects of human physiology, if an entity is homeostatically controlled it does not imply that its value is necessarily absolutely steady in health. Core body temperature is, for instance, regulated by a homeostat with temperature sensors in, amongst others, however the set point of the regulator is regularly reset. For instance, core temperature in humans varies during the course of the day, with the lowest temperatures occurring at night. The temperature regulators set point is readjusted in adult women at the start of the phase of the menstrual cycle. The temperature regulators set point is reset during infections to produce a fever, Homeostasis does not govern every activity in the body. For instance the signal from the sensor to the effector is, of necessity, highly variable in order to information about the direction. Similarly the effector’s response needs to be adjustable to reverse the error – in fact it should be very nearly in proportion to the error that is threatening the internal environment. The sensors send messages via sensory nerves to the medulla oblongata of the brain indicating whether the pressure has fallen or risen. One of the effector organs is the heart rate is stimulated to rise when the arterial blood pressure falls. Thus the heart rate is not homeostatically controlled, but is one of effector responses to errors in the blood pressure. Another example is the rate of sweating, the blood urea concentration is an example
16.
Perception
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Perception is the organization, identification, and interpretation of sensory information in order to represent and understand the environment. All perception involves signals in the system, which in turn result from physical or chemical stimulation of the sense organs. For example, vision involves light striking the retina of the eye, smell is mediated by odor molecules, Perception is not the passive receipt of these signals, but is shaped by learning, memory, expectation, and attention. Perception can be split into two processes, firstly, processing sensory input, which transforms these low-level information to higher-level information. Secondly, processing which is connected with a persons concepts and expectations, Perception depends on complex functions of the nervous system, but subjectively seems mostly effortless because this processing happens outside conscious awareness. Since the rise of psychology in the 19th Century, psychologys understanding of perception has progressed by combining a variety of techniques. Psychophysics quantitatively describes the relationships between the qualities of the sensory input and perception. Sensory neuroscience studies the mechanisms underlying perception. Perceptual systems can also be studied computationally, in terms of the information they process, Perceptual issues in philosophy include the extent to which sensory qualities such as sound, smell or color exist in objective reality rather than in the mind of the perceiver. The perceptual systems of the brain enable individuals to see the world around them as stable, even though the information is typically incomplete. Human and animal brains are structured in a way, with different areas processing different kinds of sensory information. Some of these take the form of sensory maps, mapping some aspect of the world across part of the brains surface. These different modules are interconnected and influence each other, for instance, taste is strongly influenced by smell. The process of perception begins with an object in the real world, by means of light, sound or another physical process, the object stimulates the bodys sensory organs. These sensory organs transform the energy into neural activity—a process called transduction. This raw pattern of activity is called the proximal stimulus. These neural signals are transmitted to the brain and processed, the resulting mental re-creation of the distal stimulus is the percept. An example would be a shoe, the shoe itself is the distal stimulus
17.
Motor control
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Motor control is the process by which humans and animals use their brain/cognition to activate and coordinate the muscles and limbs involved in the performance of a motor skill. Successful motor control is crucial to interacting with the world, not only determining action capabilities, areas of study related to motor control are motor coordination, motor learning, signal processing, and perceptual control theory. Reaction time refers to the period of time between when the stimulus is presented, and the end of the response, Movement time is the time it takes to complete the movement. The classical definition of a loop system for human movement comes from Jack A. Adams, „ A closed loop system has feedback, error detection. There is a reference that specifies the value for the system. A closed loop system is self regulating by compensating for deviating from the reference. ”Most movements that are carried out during day-to-day activity are formed using a process of accessing sensory information. This type of control is called feedback control, as it relies on sensory feedback to control movements. Feedback control is a form of motor control, relying on sensory information about performance. This sensory input, while processed, does not necessarily cause conscious awareness of the action, closed loop control is a feedback based mechanism of motor control, where any act on the environment creates some sort of change that affects future performance through feedback. Closed loop motor control is best suited to continuously controlled actions and these movements are subject to a speed/accuracy trade-off, because sensory processing is being used to control the movement, the faster the movement is carried out, the less accurate it becomes. Adams is, “An open loop system has no feedback or mechanisms for error regulation, the input events for a system exert their influence, the system effects its transformation on the input and the system has an output. A traffic light with fixed timing snarls traffic when the load is heavy, the system has no compensatory capability. ”Some movements, however, occur too quickly to integrate sensory information, and instead must rely on feed forward control. Open loop control is a feed forward form of motor control, to best study this type of control, most research focuses on deafferentation studies, often involving cats or monkeys whose sensory nerves have been disconnected from their spinal cords. Monkeys who lost all information from their arms resumed normal behavior after recovering from the deafferentation procedure. Most skills were relearned, but fine motor control became very difficult, a core motor control issue is coordinating the various components of the motor system to act in unison to produce movement. In turn, muscles generate forces which actuate joints, getting the pieces to work together is a challenging problem for the motor system and how this problem is resolved is an active area of study in motor control research. In some cases the coordination of motor components is hard-wired, consisting of fixed neuromuscular pathways that are called reflexes. Reflexes are typically characterized as automatic and fixed motor responses, reflexes play a fundamental role in stabilizing the motor system, providing almost immediate compensation for small perturbations and maintaining fixed execution patterns
18.
Self-awareness
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Self-awareness is the capacity for introspection and the ability to recognize oneself as an individual separate from the environment and other individuals. It is not to be confused with consciousness in the sense of qualia, while consciousness is a term given to being aware of ones environment and body and lifestyle, self-awareness is the recognition of that awareness. There are questions regarding what part of the brain allows us to be self-aware, Ramachandran has speculated that mirror neurons may provide the neurological basis of human self-awareness. In an essay written for the Edge Foundation in 2009 Ramachandran gave the explanation of his theory. This could be the basis of introspection, and of the reciprocity of self awareness. There is obviously a chicken-or-egg question here as to which evolved first, the main point is that the two co-evolved, mutually enriching each other to create the mature representation of self that characterizes modern humans. Studies have been done mainly on primates to test if self-awareness is present, apes, monkeys, elephants, and dolphins have been studied most frequently. The most relevant studies to this day that represent self-awareness in animals have been done on chimpanzees, dolphins, self-awareness in animals is tested through mirror self recognition. The ‘Red Spot Technique’ created and experimented by Gordon Gallup studies self-awareness in animals, in this technique, a red odorless spot is placed on an anesthetized primates forehead. The spot is placed on the forehead so that it can only be seen through a mirror, once the individual awakens, independent movements toward the spot after seeing their reflection in a mirror are observed. Animals that can recognize themselves in mirrors can conceive of themselves, Three elephants were exposed to large mirrors where experimenters studied the reaction when they saw their reflection. These elephants were given the mark test in order to see whether they were aware of what they were looking at. This visible mark was applied on the elephants and the researchers reported a large progress with self-awareness, the elephants shared this success rate with other animals such as monkeys and dolphins. Dolphins were put to a similar test and achieved the same results, diana Reiss, a psycho-biologist at the New York Aquarium discovered that bottlenose dolphins can recognize themselves in mirrors. Researchers also used the mark test or mirror test to study the magpies self-awareness, as a majority of birds are blind below the beak, Prior and colleagues marked the birds’ neck with three different colors, red, yellow and a black imitation, as magpies are originally black. When placed in front of a mirror, the birds with the red and yellow spots began scratching at their necks, during one trial with a mirror and a mark, three out of the five magpies showed a minimum of one example of self-directed behavior. The magpies explored the mirror by moving toward it and looking behind it, one of the magpies, Harvey, during several trials would pick up objects, pose, do some wing-flapping, all in front of the mirror with the objects in his beak. This represents a sense of self-awareness, knowing what is going on within himself, a few slight occurrences of behavior towards the magpies own body happened in the trial with the black mark and the mirror
19.
Cognition
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Cognition is the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses. Human cognition is conscious and unconscious, concrete or abstract, as well as intuitive, cognitive processes use existing knowledge and generate new knowledge. These and other different approaches to the analysis of cognition are synthesised in the field of cognitive science. Within psychology and philosophy, the concept of cognition is closely related to concepts such as mind. It encompasses the functions, mental processes, and states of intelligent entities. It is also used in a branch of psychology called social cognition to explain attitudes, attribution. In cognitive psychology and cognitive engineering, cognition is typically assumed to be processing in a participant’s or operator’s mind or brain. Cognition can in specific and abstract sense also be artificial. The term cognition is often used to mean cognitive abilities or cognitive skills. The word cognition comes from the Latin verb cognosco meaning to conceptualize or to recognize, Cognition is a word that dates back to the 15th century, when it meant thinking and awareness. Attention to the process came about more than eighteen centuries ago, beginning with Aristotle and his interest in the inner workings of the mind. Aristotle focused on cognitive areas pertaining to memory, perception, wilhelm Wundt heavily emphasized the notion of what he called introspection, examining the inner feelings of an individual. With introspection, the subject had to be careful to describe his or her feelings in the most objective manner possible in order for Wundt to find the information scientific, Hermann Ebbinghaus conducted cognitive studies that mainly examined the function and capacity of human memory. Ebbinghaus developed his own experiment in which he constructed over 2,000 syllables made out of nonexistent words and he then examined his own personal ability to learn these non-words. He purposely chose non-words as opposed to words to control for the influence of pre-existing experience on what the words might symbolize. Ebbinghaus observed and hypothesized a number of variables that may have affected his ability to learn, one of the reasons, he concluded, was the amount of time between the presentation of the list of stimuli and the recitation or recall of same. Ebbinghaus was the first to record and plot a curve. His work heavily influenced the study of serial position and its effect on memory, mary Whiton Calkins was an influential American pioneer in the realm of psychology
20.
Central nucleus of the amygdala
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The central nucleus of the amygdala is a nucleus within the amygdala. It serves as the major output nucleus of the amygdala and participates in receiving and processing pain information, CeA connects with brainstem areas that control the expression of innate behaviors and associated physiological responses. CeA is responsible for autonomic components of emotions primarily through output pathways to the lateral hypothalamus, the regions described as amygdala nuclei encompass several structures with distinct connectional and functional characteristics in humans and other animals. Among these nuclei are the complex, the cortical nucleus, the medial nucleus. The basolateral complex can be subdivided into the lateral, the basal. The amygdalofugal pathway is one of the three principal pathways by which fibers leave the amygdala, the other main efferent pathways from the amygdala are the stria terminalis and anterior commissure. The anterior commissure also serves to connect the two amygdala, psychological stressor induced an increase in both CRH mRNA levels and CRH content in the CEA. CeA dopamine function is involved in modulation of disengagement behavior, …μ-ORs in the CeA in a positive regulation of sodium intake
21.
Secondary somatosensory cortex
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The human secondary somatosensory cortex is a region of cortex in the parietal operculum on the ceiling of the lateral sulcus. Experiments involving ablation of the somatosensory cortex in primates indicate that this cortical area is involved in remembering the differences between tactile shapes and textures. Functional neuroimaging studies have found S2 activation in response to touch, pain, visceral sensation. In monkeys, apes and hominids, including humans, region S2 is divided several areas. An area at the entrance to the sulcus, adjoining the primary somatosensory cortex, is called the parietal ventral area. Posterior to PV is the somatosensory area. Deeper in the lateral sulcus lies the ventral area, whose outer edge adjoins areas PV and S2. In humans, the somatosensory cortex includes parts of Brodmann area 40 and 43. Areas PV and S2 both map the body surface, functional neuroimaging in humans has revealed that in areas PV and S2 the face is represented near the entrance to the lateral sulcus, and the hands and feet deeper in the fissure. Individual neurons in areas PV and S2 receive input from wide areas of the body surface, area PV connects densely with BA5 and the premotor cortex. Area S2 is interconnected with BA1 and densely so with BA 3b, areas S2 in the left and right hemispheres are densely interconnected, and stimulation on one side of the body will activate area S2 in both hemispheres. Brodmann area 5 Brodmann area 7
22.
Spinothalamic tract
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The spinothalamic tract is a sensory pathway from the skin to the thalamus. From the ventral posterolateral nucleus in the thalamus, sensory information is relayed upward to the cortex of the postcentral gyrus. The spinothalamic tract consists of two adjacent pathways, anterior and lateral, the anterior spinothalamic tract carries information about crude touch. The lateral spinothalamic tract conveys pain and temperature, in the spinal cord, the spinothalamic tract has somatotopic organization. This is the organization of its cervical, thoracic, lumbar, and sacral components. The pathway decussates at the level of the cord, rather than in the brainstem like the posterior column-medial lemniscus pathway. There are two parts of the spinothalamic tract, The lateral spinothalamic tract transmits pain and temperature. The anterior spinothalamic tract transmits crude touch and firm pressure, the spinothalamic tract, like the dorsal column-medial lemniscus tract, uses three neurons to convey sensory information from the periphery to conscious level at the cerebral cortex. These secondary neurons are called tract cells, the axons of the tract cells cross over to the other side of the spinal cord via the anterior white commissure, and to the anterolateral corner of the spinal cord. Decussation usually occurs 1-2 spinal nerve segments above the point of entry, the axons travel up the length of the spinal cord into the brainstem, specifically the rostral ventromedial medulla. Traveling up the brainstem, the tract moves dorsally, the neurons ultimately synapse with third-order neurons in several nuclei of the thalamus—including the medial dorsal, ventral posterior lateral, and ventral posterior medial nuclei. From there, signals go to the cortex, the primary somatosensory cortex. The types of information transmitted via the spinothalamic tract are described as affective sensation. This means that the sensation is accompanied by a compulsion to act, for instance, an itch is accompanied by a need to scratch, and a painful stimulus makes us want to withdraw from the pain. There are two sub-systems identified, Direct Indirect, in the nervous system, the anterolateral system is an ascending pathway that conveys pain, temperature, and crude touch from the periphery to the brain. This fact aids in determining whether a lesion is in the brain or the spinal cord, with lesions in the brain stem or higher, deficits of pain perception, touch sensation, and proprioception are all contralateral to the lesion. With spinal cord lesions, however, the deficit in perception is contralateral to the lesion. Unilateral lesions usually cause contralateral anaesthesia, anaesthesia will normally begin 1-2 segments below the level of lesion, affecting all caudal body areas
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Sulcus (neuroanatomy)
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In neuroanatomy, a sulcus is a depression or groove in the cerebral cortex. It surrounds a gyrus, creating the characteristic folded appearance of the brain in humans, Sulci are one of three parts of the cerebral cortex, the others being the gyri and the fissures. The three different parts create a surface area for the human brain and other mammalian brains. When looking at the brain, two-thirds of the surface are hidden in the grooves. The sulci and fissures are both grooves in the cortex but they are differentiated by size, a sulcus is a shallower groove that surrounds a gyrus. A fissure is a furrow that divides the brain into lobes. However this distinction is not always clear, for example, the lateral sulcus is also known as the lateral fissure or the Sylvian fissure, and the central sulcus is also known as the central fissure or the Rolandic fissure. As the surface area of the brain increases more functions are made possible, a smooth-surfaced brain is only able to grow to a certain extent. A depression, sulcus, in the area allows for continued growth. This in turn allows for the functions of the brain to continue growing, the sulcal pattern varies between human individuals, and the most elaborate overview on this variation is probably an atlas by Ono, Kubick and Abernathey, Atlas of the Cerebral Sulci. Some of the more prominent sulci are, however, seen across individuals - and even species - making a common nomenclature across individuals, in humans, cerebral convolutions appear at about 5 months and take at least into the first year after birth to fully develop. The potential influences of genetic, epigenetic and environmental factors are not fully understood and it has been found that the width of cortical sulci not only increases with age, but also with cognitive decline in the elderly. Axial sulcus develops in the axis of a rapidly growing homogeneous area e. g. postcalcarine sulcus in the long axis of the striate area. Operculated sulcus separates by its lips into two areas and contains an area in the walls of the sulcus. On the basis of formation, Primary sulci, formed before birth, secondary sulcus, is produced by factors other than the exuberant growth in the adjoining areas of the cortex. Examples are the lateral and parieto-occipital sulci, on the basis of Depth, Complete sulcus is very deep so as to cause elevation in the walls of the lateral ventricle. Examples are the collateral and calcarine sulci, incomplete sulci are superficially situated and are not very deep, E. g. paracentral sulcus. Mammals that have smooth-surfaced or nonconvoluted brains are called lissencephalics and those that have folded or convoluted brains gyrencephalics, the division between the two groups occurs when cortical surface area is about 10 cm2 and the brain has a volume of 3–4 cm3
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Cytoarchitecture
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Cytoarchitecture, also known as cytoarchitectonics, is the study of the cellular composition of the bodys tissues under the microscope. The study of the parcellation of nerve fibers into layers forms the subject of myeloarchitectonics, defining cerebral cytoarchitecture began with the advent of histology—the science of slicing and staining brain slices for examination. It is credited to the Viennese psychiatrist Theodor Meynert, who in 1867 noticed regional variations in the structure of different parts of the gray matter in the cerebral hemispheres. Paul Flechsig was the first to present the cytoarchitecture of human brain into 40 areas, alfred Walter Campbell, then, present the cytoarchitecture of the human brain into 14 areas. Sir Grafton Elliot Smith, a New South Wales native working in Cairo, korbinian Brodmann worked on the brains of diverse mammalian species and developed a division of the cerebral cortex into 52 discrete areas. Brodmann used numbers to categorize the different architectural areas and he believed each of these regions served a unique functional purpose. Constantin von Economo and Georg N. Koskinas, two neurologists in Vienna, produced a work in brain research by defining 107 cortical areas on the basis of cytoarchitectonic criteria. They used letters to categorize the architecture, e. g. F for areas of the frontal lobe, the Nissl staining technique is commonly used for determining the cytoarchitectonics of neuroanatomical structures, using common agents such as thionin, cresyl violet, or neutral red. These dyes intensely stain Nissl bodies, which are abundant in neurons, other common staining techniques used by histologists in other tissues leave brain tissue appearing largely homogenous and do not reveal the level of organization apparent in a Nissl stain
25.
Granule cell
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The name granule cell has been used by anatomists for a number of different types of neuron whose only common feature is that they all have very small cell bodies. Cerebellar granule cells account for the majority of neurons in the human brain and these granule cells receive excitatory input from mossy fibers originating from pontine nuclei. Cerebellar granule cells send parallel fibers up through the Purkinje layer into the layer where they branch out. These parallel fibers form thousands of excitatory granule-cell-Purkinje-cell synapses onto the intermediate, layer 4 granule cells of the cerebral cortex receive inputs from the thalamus and send projections to supragranular layers 2-3, but also to infragranular layers of the cerebral cortex. Granule cells in different brain regions are functionally and anatomically diverse, the only thing they have in common is smallness. For instance, olfactory bulb granule cells are GABAergic and axonless and these two populations of granule cells are also the only major neuronal populations that undergo adult neurogenesis, while cerebellar and cortical granule cells do not. Granule cells have a typical of a neuron consisting of dendrites, a soma. Dendrites, Each granule cell has 3 –4 stubby dendrites which end in a claw, Each of the dendrites are only about 15 μm in length. Soma, Granule cells all have a small diameter of approximately 10 μm. Axon, Each granule cell sends a single axon onto the Purkinje cell dendritic tree, the axon has an extremely narrow diameter, ½ micron. Synapse, 100-300,000 granule cell axons synapse onto a single Purkinje cell, the granule cells, produced by the rhombic lip, are found in the granule cell layer of the cerebellar cortex. They are characterized by a small soma and several short dendrites which terminate with claw-shaped endings. In the transmission electron microscope, these cells are characterized by a darkly stained nucleus surrounded by a rim of cytoplasm. The axon ascends into the layer where it splits to form parallel fibers. The principal cell type of the gyrus is the granule cell. The dentate granule cell has a cell body with a width of approximately 10 μm. The granule cell has a characteristic cone-shaped tree of spiny apical dendrites, the dendrite branches project throughout the entire molecular layer and the furthest tips of the dendritic tree end just at the hippocampal fissure or at the ventricular surface. The granule cells are packed in the granular cell layer of the dentate gyrus
26.
Anatomical terms of location
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Standard anatomical terms of location deal unambiguously with the anatomy of animals, including humans. All vertebrates have the basic body plan – they are strictly bilaterally symmetrical in early embryonic stages. That is, they have left and right halves if divided down the centre. For these reasons, the directional terms can be considered to be those used in vertebrates. By extension, the terms are used for many other organisms as well. While these terms are standardized within specific fields of biology, there are unavoidable, sometimes dramatic, for example, differences in terminology remain a problem that, to some extent, still separates the terminology of human anatomy from that used in the study of various other zoological categories. The vertebrates and Craniata share a heritage and common structure. To avoid ambiguities this terminology is based on the anatomy of each animal in a standard way, for humans, one type of vertebrate, anatomical terms may differ from other forms of vertebrates. Thus what is on top of a human is the head, whereas the top of a dog may be its back, for example, many species are not even bilaterally symmetrical. In these species, terminology depends on their type of symmetry, all descriptions are with respect to the organism in its standard anatomical position, even when the organism in question has appendages in another position. This helps avoid confusion in terminology when referring to the organism in different postures. In humans, this refers to the body in a position with arms at the side. While the universal vertebrate terminology used in medicine would work in human medicine. Many anatomical terms can be combined, either to indicate a position in two axes simultaneously or to indicate the direction of a movement relative to the body, for example, anterolateral indicates a position that is both anterior and lateral to the body axis. There is no limit to the contexts in which terms may be modified to qualify each other in such combinations. Generally the modifier term is truncated and an o or an i is added in prefixing it to the qualified term, where desirable three or more terms may be agglutinated or concatenated, as in anteriodorsolateral. Such terms sometimes used to be hyphenated, but the tendency is to omit the hyphen. There is however little basis for any rule to interfere with choice of convenience in such usage
27.
Spindle neuron
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Other neurons tend to have many dendrites, and the polar-shaped morphology of spindle neurons is unique. A neurons dendrites receive signals, and its axon sends them, recently they have been discovered in the dorsolateral prefrontal cortex of humans. The appearance of spindle neurons in distantly related clades suggests that they represent convergent evolution, austrian psychiatrist and neurologist Constantin von Economo discovered spindle neurons and described them in 1929, which is why they are sometimes called von Economo neurons. Spindle neurons are large cells that may allow rapid communication across the relatively large brains of great apes, elephants. Although rare in comparison to other neurons, spindle neurons are abundant, however, the concentration of spindle cells has been measured to be three times higher in cetaceans in comparison to humans. They have only been found far in the anterior cingulate cortex, fronto-insular cortex. The observation that spindle neurons only occur in a significant group of animals has led to speculation that they are of great importance in human evolution and/or brain function. Their restriction to great apes leads to the hypothesis that they developed no earlier than 15-20 million years ago, recently, primitive forms of spindle neurons have also been discovered in macaque monkey brains and raccoons. Neuronal volumes of ACC spindle neurons were larger in humans and the gracile chimpanzees than the neurons of the robust gorillas. Allmans team proposes that spindle neurons help channel neural signals from deep within the cortex to relatively distant parts of the brain. Specifically, Allmans team found signals from the ACC are received in Brodmanns area 10, in the frontal polar cortex, according to Allman, this neural relay appears to convey motivation to act, and concerns the recognition of error. The ACC is also active during demanding tasks requiring judgment and discrimination, during difficult tasks, or when experiencing intense love, anger, or lust, activation of the ACC increases. In brain imaging studies, the ACC has specifically found to be active when mothers hear infants cry. This fronto-insular cortex is connected to the insula, a region that is roughly the size of a thumb in each hemisphere of the human brain. Moreover, this region of the right hemisphere is crucial to navigation and perception of three-dimensional rotations, the largest number of ACC spindle neurons are found in humans, fewer in the gracile great apes, and fewest in the robust great apes. In both humans and bonobos they are found in clusters of 3 to 6 neurons. They are found in humans, bonobos, common chimpanzees, gorillas, orangutans, some cetaceans, all of the primates examined had more spindle cells in the fronto-insula of the right hemisphere than in the left. In contrast to the number of spindle cells found in the ACC of the gracile bonobos and chimpanzees
28.
Lobes of the brain
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The lobes of the brain were originally a purely anatomical classification, but have been shown also to be related to different brain functions. The cerebrum, the largest portion of the brain, is divided into lobes. If not specified, the lobes of the brain refers to the cerebrum. Terminologia Anatomica divides cerebrum into 6 lobes, the frontal lobe is located at the front of each cerebral hemisphere and positioned in front of the parietal lobe and above and in front of the temporal lobe. It is separated from the parietal lobe by a space between tissues called the sulcus, and from the temporal lobe by a deep fold called the lateral sulcus also called the Sylvian fissure. The precentral gyrus, forming the border of the frontal lobe, contains the primary motor cortex. The frontal lobe contains most of the neurons in the cerebral cortex. The dopamine system is associated with reward, attention, short-term memory tasks, planning, dopamine tends to limit and select sensory information arriving from the thalamus to the forebrain. The parietal lobe is positioned above the occipital lobe and behind the frontal lobe, the major sensory inputs from the skin, relay through the thalamus to the parietal lobe. Several areas of the parietal lobe are important in language processing, the somatosensory cortex can be illustrated as a distorted figure — the homunculus, in which the body parts are rendered according to how much of the somatosensory cortex is devoted to them. The superior parietal lobule and inferior parietal lobule are the areas of body or spatial awareness. A lesion commonly in the superior or inferior parietal lobule leads to hemineglect. The occipital lobe is the 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 posterior pole of the occipital lobe. V1 is often also called striate cortex because it can be identified by a stripe of myelin. Visually driven regions outside V1 are called extrastriate cortex, there are many extrastriate regions, and these are specialized for different visual tasks, such as visuospatial processing, color differentiation, and motion perception. The temporal lobe is located beneath the lateral fissure on both hemispheres of the mammalian brain. The temporal lobe is involved in processing sensory input into derived meanings for the retention of visual memories, language comprehension
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Interoception
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A sense is a physiological capacity of organisms that provides data for perception. The senses and their operation, classification, and theory are overlapping topics studied by a variety of fields, most notably neuroscience, cognitive psychology, the nervous system has a specific sensory system or organ, dedicated to each sense. Humans have a multitude of senses, sight, hearing, taste, smell, and touch are the five traditionally recognized senses. However, what constitutes a sense is a matter of debate, leading to difficulties in defining what exactly a distinct sense is. Other animals also have receptors to sense the world around them, humans have a comparatively weak sense of smell and a stronger sense of sight relative to many other mammals while some animals may lack one or more of the traditional five senses. Some animals may also intake and interpret sensory stimuli in different ways. Some species of animals are able to sense the world in a way humans cannot, with some species able to sense electrical and magnetic fields. There is no agreement as to the number of senses because of differing definitions of what constitutes a sense. The senses are frequently divided into exteroceptive and interoceptive, Exteroceptive senses are senses that perceive the bodys own position, motion, external senses include the traditional five, sight, hearing, touch, smell and taste, as well as thermoception and possibly an additional weak magnetoception. Proprioceptive senses include nociception, equilibrioception, proprioception, interoceptive senses are senses that perceive sensations in internal organs. Non-human animals may possess senses that are absent in humans, such as electroreception and detection of polarized light, in Buddhist philosophy, Ayatana or sense-base includes the mind as a sense organ, in addition to the traditional five. This addition to the commonly acknowledged senses may arise from the psychological orientation involved in Buddhist thought, the mind considered by itself is seen as the principal gateway to a different spectrum of phenomena that differ from the physical sense data. This way of viewing the human sense system indicates the importance of internal sources of sensation and perception that complements our experience of the external world, there are two types of photoreceptors, rods and cones. Rods are very sensitive to light, but do not distinguish colors, cones distinguish colors, but are less sensitive to dim light. There is some disagreement as to whether this one, two or three senses. Neuroanatomists generally regard it as two senses, given that different receptors are responsible for the perception of color and brightness, the inability to see is called blindness. Blindness may result from damage to the eyeball, especially to the retina, damage to the nerve that connects each eye to the brain. Temporary or permanent blindness can be caused by poisons or medications, people with blindsight are usually not aware that they are reacting to visual sources, and instead just unconsciously adapt their behaviour to the stimulus
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Hominidae
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Several revisions in classifying the great apes have caused the use of the term hominid to vary over time. Its original meaning referred only to humans and their closest non-extant relatives and that restrictive meaning has now been largely assumed by the term hominin, which comprises all members of the human clade after the split from the chimpanzees. The current, 21st-century meaning of hominid includes all the great apes including humans, the most recent common ancestor of all Hominidae lived roughly 14 million years ago, when the ancestors of the orangutans speciated from the ancestral line of the other three genera. Those ancestors of the family Hominidae had already speciated from the family Hylobatidae, in the early Miocene, about 22 million years ago, there were many species of arboreally adapted primitive catarrhines from East Africa, the variety suggests a long history of prior diversification. Fossils at 20 million years ago include fragments attributed to Victoriapithecus, the most recent of these far-flung Miocene apes is Oreopithecus, from the fossil-rich coal beds in northern Italy and dated to 9 million years ago. Species close to the last common ancestor of gorillas, chimpanzees and humans may be represented by Nakalipithecus fossils found in Kenya and Ouranopithecus found in Greece. Molecular evidence suggests that between 8 and 4 million years ago, first the gorillas, and then the split off from the line leading to the humans. Human DNA is approximately 98. 4% identical to that of chimpanzees when comparing single nucleotide polymorphisms, the earliest fossils argued by some to belong to the human lineage are Sahelanthropus tchadensis and Orrorin tugenensis, followed by Ardipithecus, with species Ar. kadabba and Ar. ramidus. The classification of the apes has been revised several times in the last few decades. The original meaning of the referred to only humans and their closest relatives—what is now the modern meaning of the term hominin. And the meaning of the taxon Hominidae changed gradually, leading to a different usage of hominid that today all the great apes including humans. A hominid is a member of the family Hominidae, the apes, orangutans, gorillas, chimpanzees. A hominine is a member of the subfamily Homininae, gorillas, chimpanzees, a hominin is a member of the tribe Hominini, Chimpanzees and humans. A homininan is a member of the subtribe Hominina of the tribe Hominini, a human is a member of the genus Homo, of which Homo sapiens is the only extant species, and within that Homo sapiens sapiens is the only surviving subspecies. For each clade it is indicated approximately when newer extant clades emerged, some texts will refer to Homonini as the Hominina branch. Many scientists, including paleoanthropologists, continue to use the term hominid to mean humans, as mentioned, Hominidae was originally the name given to the family of humans and their close relatives, with the other great apes all being placed in a separate family, the Pongidae. However, that eventually made Pongidae paraphyletic because at least one great ape species proved to be more closely related to humans than to other great apes. Most taxonomists today encourage monophyletic groups—this would require, in this case, thus, many biologists now assign Pongo to the family Hominidae
31.
Anterior cingulate cortex
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The anterior cingulate cortex is the frontal part of the cingulate cortex that resembles a collar surrounding the frontal part of the corpus callosum. It consists of Brodmann areas 24,32, and 33 and it appears to play a role in a wide variety of autonomic functions, such as regulating blood pressure and heart rate. It is also involved in certain functions, such as reward anticipation, decision-making, impulse control. The anterior cingulate cortex can be divided based on cognitive. The ACC seems to be involved when effort is needed to carry out a task. On a cellular level, the ACC is unique in its abundance of specialized neurons called spindle cells and these cells are a relatively recent occurrence in evolutionary terms and contribute to this brain regions emphasis on addressing difficult problems, as well as the pathologies related to the ACC. A typical task that activates the ACC involves eliciting some form of conflict within the participant that can result in an error. One such task is called the Eriksen flanker task and consists of an arrow pointing to the left or right, another very common conflict-inducing stimulus that activates the ACC is the Stroop task, which involves naming the color ink of words that are either congruent or incongruent. Conflict occurs because people’s reading abilities interfere with their attempt to name the word’s ink color. A variation of this task is the Counting-Stroop, during which people count either neutral stimuli or interfering stimuli by pressing a button, many studies attribute specific functions such as error detection, anticipation of tasks, attention, ) motivation, and modulation of emotional responses to the ACC. The most basic form of ACC theory states that the ACC is involved with error detection, Evidence has been derived from studies involving a Stroop task. They found that for more competitive stimuli ACC activation was greater, a similar theory poses that the ACC’s primary function is the monitoring of conflict. In Eriksen flanker task, incompatible trials produce the most conflict, upon detection of a conflict, the ACC then provides cues to other areas in the brain to cope with the conflicting control systems. Evidence from electrical studies Evidence for ACC as having an error detection function comes from observations of error-related negativity uniquely generated within the ACC upon error occurrences, a distinction has been made between an ERP following incorrect responses and a signal after subjects receive feedback after erroneous responses. No-one has clearly demonstrated that the ERN comes from the ACC, reinforcement learning ERN theory poses that there is a mismatch between actual response execution and appropriate response execution, which results in an ERN discharge. Furthermore, this theory predicts that, when the ACC receives conflicting input from control areas in the brain, varying levels of dopamine are believed to influence the optimization of this filter system by providing expectations about the outcomes of an event. The ERN, then, serves as a beacon to highlight the violation of an expectation, research on the occurrence of the feedback ERN shows evidence that this potential has larger amplitudes when violations of expectancy are large. In other words, if an event is not likely to happen, other studies have examined whether the ERN is elicited by varying the cost of an error and the evaluation of a response
32.
Empathy
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Empathy is the capacity to understand or feel what another person is experiencing from within the other persons frame of reference, i. e. the capacity to place oneself in anothers position. Empathy is seeing with the eyes of another, listening with the ears of another, there are many definitions for empathy which encompass a broad range of emotional states. Types of empathy include cognitive empathy, emotional empathy, and somatic empathy, the English word empathy is derived from the Ancient Greek word εμπάθεια. This, in turn, comes from εν and πάθος, the term was adapted by Hermann Lotze and Robert Vischer to create the German word Einfühlung, which was translated by Edward B. Titchener into the English term empathy, alexithymia is a word used to describe a deficiency in understanding, processing or describing emotions in oneself as opposed to in others. This term comes from the negation of two Ancient Greek words, αλέξω and θυμός, thus alexithymia literally means pushing away your emotions. It also is the ability to feel and share another persons emotions, some believe that empathy involves the ability to match anothers emotions, while others believe that empathy involves being tenderhearted toward another person. Having empathy also can include having the understanding that there are factors that go into decision making. Past experiences have an influence on the making of today. Understanding this allows a person to have empathy for individuals who sometimes make decisions to a problem that most individuals would respond with an obvious response. Broken homes, childhood trauma, lack of parenting and many factors can influence the connections the brain which a person uses to make decisions in the future. Martin Hoffman is a Psychologist who studied the development of empathy, according to Hoffman everyone is born with the capability of feeling empathy. Compassion and sympathy are two terms that many associate with empathy, but all three of these terms are unique, even so, definitions vary, contributing to the challenge of defining empathy. Compassion is often defined as an emotion we feel when others are in need, Sympathy is a feeling of care and understanding for someone in need. It can also be understood as having the separateness of defining oneself, some include in sympathy also an empathic concern, a feeling of concern for another, in which some scholars include the wish to see them better off or happier. Empathy is distinct also from pity and emotional contagion, pity is feeling that another is in trouble and in need of help as they cannot fix their problems themselves, often described as feeling sorry for someone. Emotional contagion is when a person catches the emotions that others are showing without necessarily recognizing this is happening. Since empathy involves understanding the emotional states of people, the way it is characterized is derived from the way emotions themselves are characterized
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Heart rate
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Heart rate is the speed of the heartbeat measured by the number of contractions of the heart per minute. The heart rate can vary according to the physical needs, including the need to absorb oxygen. It is usually equal or close to the pulse measured at any peripheral point, activities that can provoke change include physical exercise, sleep, anxiety, stress, illness, and ingestion of drugs. Many texts cite the normal resting adult heart rate range from 60–100 bpm. Tachycardia is a fast heart rate, defined as above 100 bpm at rest, bradycardia is a slow heart rate, defined as below 60 bpm at rest. Several studies, as well as expert consensus indicates that the normal resting heart rate is probably closer to a range between 50–90 bpm. During sleep a slow heartbeat with rates around 40–50 bpm is common and is considered normal, when the heart is not beating in a regular pattern, this is referred to as an arrhythmia. Abnormalities of heart rate sometimes indicate disease, while heart rhythm is regulated entirely by the sinoatrial node under normal conditions, heart rate is regulated by sympathetic and parasympathetic input to the sinoatrial node. Therefore, stimulation of the accelerans nerve increases heart rate, while stimulation of the nerve decreases it. Due to individuals having a constant blood volume, one of the ways to deliver more oxygen to an organ is to increase heart rate to permit blood to pass by the organ more often. Normal resting heart rates range from 60–100 bpm, bradycardia is defined as a resting heart rate below 60 bpm. However, heart rates from 50 to 60 bpm are common among healthy people, tachycardia is defined as a resting heart rate above 100 bpm, though persistent rest rates between 80–100 bpm, mainly if they are present during sleep, may be signs of hyperthyroidism or anemia. Central nervous system such as substituted amphetamines increase heart rate. Central nervous system depressants or sedatives decrease the heart rate, there are many ways in which the heart rate speeds up or slows down. Most involve stimulant-like endorphins and hormones being released in the brain, many of which are those that are forced/enticed out by the ingestion and this section discusses target heart rates for healthy persons and are inappropriately high for most persons with coronary artery disease. The heart rate is generated by the sinoatrial node. It is also influenced by central factors through sympathetic and parasympathetic nerves, nervous influence over the heartrate is centralized within the two paired cardiovascular centres of the medulla oblongata. During rest, both centers provide slight stimulation to the heart, contributing to autonomic tone and this is a similar concept to tone in skeletal muscles
34.
Grey matter
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Grey matter is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil, glial cells, synapses, and capillaries. The colour difference arises mainly from the whiteness of myelin, in living tissue, grey matter actually has a very light grey colour with yellowish or pinkish hues, which come from capillary blood vessels and neuronal cell bodies. Grey matter refers to unmyelinated neurons and other cells of the nervous system. It is present in the brain, brainstem and cerebellum, grey matter is distributed at the surface of the cerebral hemispheres and of the cerebellum, as well as in the depths of the cerebrum, cerebellar, brainstem. Grey matter in the cord is known as the grey column which travels down the spinal cord distributed in three grey columns that are presented in an H shape. The forward-facing column is the grey column, the rear-facing one is the posterior grey column. The grey matter on the left and right side is connected by the grey commissure, the grey matter in the spinal cord consists of interneurons, as well as cell bodies. Grey matter undergoes development and growth throughout childhood and adolescence, grey matter contains most of the brains neuronal cell bodies. The grey matter includes regions of the involved in muscle control, and sensory perception such as seeing and hearing, memory, emotions, speech, decision making. The grey matter in the cord is split into three grey columns, The anterior grey column contains motor neurons. These synapse with interneurons and the axons of cells that have travelled down the pyramidal tract and these cells are responsible for the movement of muscles. The posterior grey column contains the points where sensory neurons synapse and these receives sensory information from the body, including fine touch, proprioception, and vibration. This information is sent from receptors of the skin, bones and this information is then transmitted in axons up the spinal cord in spinal tracts, including the dorsal column-medial lemniscus tract and the spinothalamic tract. The lateral grey column is the column of the spinal cord. The grey matter of the cord can be divided into different layers. These describe, in general, the purpose of the cells within the matter of the spinal cord at a particular location. High alcohol consumption has been correlated with significant reductions in grey matter volume, in the current edition of the official Latin nomenclature, Terminologia Anatomica, substantia grisea is used for English grey matter. The adjective grisea for grey is however not attested in classical Latin, the adjective grisea is derived from the French word for grey, gris
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. PMID 23466178.<
