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Scintillating Scotoma
Scintillating scotoma is a common visual aura that was first described by 19th-century physician Hubert Airy (1838–1903). Originating from the brain, it may precede a migraine headache, but can also occur acephalgically (without headache), also known as visual migraine or migraine aura. It is often confused with retinal migraine, which originates in the eyeball or socket. Signs and symptoms Many variations occur, but scintillating scotoma usually begins as a spot of flickering light near or in the center of the visual field, which prevents vision within the scotoma area. It typically affects both eyes, as it is not a problem specific to one eye. The affected area flickers but is not dark. It then gradually expands outward from the initial spot. Vision remains normal beyond the borders of the expanding scotoma(s), with objects melting into the scotoma area background similarly to the physiological blind spot, which means that objects may be seen better by not looking directly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cortical Spreading Depression
] Cortical spreading depression (CSD) or spreading depolarization (SD) is a wave of Electrophysiology, electrophysiological hyperactivity followed by a wave of inhibition. Spreading depolarization describes a phenomenon characterized by the appearance of depolarization waves of the neurons and neuroglia that propagates across the cortex at a velocity of 1.5–9.5 mm/min. CSD can be induced by hypoxic conditions and facilitates neuronal death in energy-compromised tissue. CSD has also been implicated in migraine aura, where CSD is assumed to ascend in well-nourished tissue and is typically benign in most of the cases, although it may increase the probability in migraine patients to develop a stroke. Spreading depolarization within brainstem tissues regulating functions crucial for life has been implicated in sudden unexpected death in epilepsy, by way of ion channel mutations such as those seen in Dravet syndrome, a particularly severe form of childhood epilepsy that appea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blind Spot (vision)
A blind spot, scotoma, is an obscuration of the visual field. A particular blind spot known as the ''physiological blind spot'', "blind point", or ''punctum caecum'' in medical literature, is the place in the visual field that corresponds to the lack of light-detecting photoreceptor cells on the optic disc of the retina where the optic nerve passes through the optic disc.Gregory, R., & Cavanagh, P. (2011)"The Blind Spot" Scholarpedia. Retrieved on 2011-05-21. Because there are no cells to detect light on the optic disc, the corresponding part of the field of vision is invisible. Processes in the brain interpolate the blind spot based on surrounding detail and information from the other eye, so it is not normally perceived. Although all vertebrates have this blind spot, cephalopod eyes, which are only superficially similar, do not. In them, the optic nerve approaches the receptors from behind, so it does not create a break in the retina. The first documented observation o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexa Beiser
Alexa S. Beiser is an American professor of biostatistics and public health researcher. Biography Beiser did her PhD in mathematics at Boston University, following her M.A. at the University of California, San Diego in Applied Mathematics and B.A. in Biology and Psychology from the University of California, Santa Cruz. She has worked at the Boston University School of Public Health since 1985, currently in the Framingham Heart Study (FHS) neurology group. Beiser co-developed the biostatistics doctoral program at Boston University. Research She has worked on areas such as risk factors for dementia Dementia is a disorder which manifests as a set of related symptoms, which usually surfaces when the brain is damaged by injury or disease. The symptoms involve progressive impairments in memory, thinking, and behavior, which negatively affe ..., how stress affects memory, and how physical activity can improve health for people with diabetes. She currently leads the FHS neurolo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stroke
A stroke is a disease, medical condition in which poor cerebral circulation, blood flow to the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemorrhagic, due to bleeding. Both cause parts of the brain to stop functioning properly. Signs and symptoms of a stroke may include an hemiplegia, inability to move or feel on one side of the body, receptive aphasia, problems understanding or expressive aphasia, speaking, dizziness, or Homonymous hemianopsia, loss of vision to one side. Signs and symptoms often appear soon after the stroke has occurred. If symptoms last less than one or two hours, the stroke is a transient ischemic attack (TIA), also called a mini-stroke. A subarachnoid hemorrhage, hemorrhagic stroke may also be associated with a thunderclap headache, severe headache. The symptoms of a stroke can be permanent. Long-term complications may include pneumonia and Urinary incontin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Framingham Heart Study
The Framingham Heart Study is a long-term, ongoing cardiovascular cohort study of residents of the city of Framingham, Massachusetts. The study began in 1948 with 5,209 adult subjects from Framingham, and is now on its third generation of participants. Prior to the study almost nothing was known about the epidemiology of hypertensive or arteriosclerotic cardiovascular disease. Much of the now-common knowledge concerning heart disease, such as the effects of diet, exercise, and common medications such as aspirin, is based on this longitudinal study. It is a project of the National Heart, Lung, and Blood Institute, in collaboration with (since 1971) Boston University. Various health professionals from the hospitals and universities of Greater Boston staff the project. History In 1948, the study was commissioned by Congress, with a choice made between Framingham, Massachusetts and Paintsville, Kentucky. Framingham was chosen when residents showed more general interest in heart ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monosodium Glutamate
Monosodium glutamate (MSG), also known as sodium glutamate, is the sodium salt of glutamic acid. MSG is found naturally in some foods including tomatoes and cheese in this glutamic acid form. MSG is used in cooking as a flavor enhancer with an umami taste that intensifies the meaty, savory flavor of food, as naturally occurring glutamate does in foods such as stews and meat soups. MSG was first prepared in 1908 by Japanese biochemist Kikunae Ikeda, who was trying to isolate and duplicate the savory taste of ''kombu'', an edible seaweed used as a base for many Japanese soups. MSG balances, blends, and rounds the perception of other tastes. MSG is commonly used and found in stock (bouillon) cubes, soups, ramen, gravy, stews, condiments, savory snacks, etc. The U.S. Food and Drug Administration has given MSG its generally recognized as safe (GRAS) designation. It is a popular belief that MSG can cause headaches and other feelings of discomfort, known as "Chinese ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Self-report
A self-report study is a type of survey, questionnaire, or poll in which respondents read the question and select a response by themselves without any outside interference. A ''self-report'' is any method which involves asking a participant about their feelings, attitudes, beliefs and so on. Examples of self-reports are questionnaires and interviews; self-reports are often used as a way of gaining participants' responses in observational studies and experiments. Self-report studies have validity problems. Patients may exaggerate symptoms in order to make their situation seem worse, or they may under-report the severity or frequency of symptoms in order to minimize their problems. Patients might also simply be mistaken or misremember the material covered by the survey. Questionnaires and interviews Questionnaires are a type of self-report method which consist of a set of questions usually in a highly structured written form. Questionnaires can contain both open questions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peripheral Vision
Peripheral vision, or ''indirect vision'', is vision as it occurs outside the point of fixation, i.e. away from the center of gaze or, when viewed at large angles, in (or out of) the "corner of one's eye". The vast majority of the area in the visual field is included in the notion of peripheral vision. "Far peripheral" vision refers to the area at the edges of the visual field, "mid-peripheral" vision refers to medium eccentricities, and "near-peripheral", sometimes referred to as "para-central" vision, exists adjacent to the center of gaze. Boundaries Inner boundaries The inner boundaries of peripheral vision can be defined in any of several ways depending on the context. In everyday language the term "peripheral vision" is often used to refer to what in technical usage would be called "far peripheral vision." This is vision outside of the range of stereoscopic vision. It can be conceived as bounded at the center by a circle 60° in radius or 120° in diameter, centered aro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Occipital Cortex
The occipital lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The name derives from its position at the back of the head, from the Latin ''ob'', "behind", and ''caput'', "head". The occipital lobe is the visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area 17, commonly called V1 (visual one). 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 occipital pole. V1 is often also called striate cortex because it can be identified by a large stripe of myelin, the Stria of Gennari. 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. Bilateral lesions of the occipital lobe can lead ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Widmanstätten Pattern
Widmanstätten patterns, also known as Thomson structures, are figures of long nickel–iron crystals, found in the octahedrite iron meteorites and some pallasites. They consist of a fine interleaving of kamacite and taenite bands or ribbons called '' lamellae''. Commonly, in gaps between the lamellae, a fine-grained mixture of kamacite and taenite called plessite can be found. Widmanstätten patterns describe features in modern steels, titanium, and zirconium alloys. Discovery In 1808, these figures were observed by Count Alois von Beckh Widmanstätten, the director of the Imperial Porcelain works in Vienna. While flame heating iron meteorites, Widmanstätten noticed color and luster zone differentiation as the various iron alloys oxidized at different rates. He did not publish his findings, claiming them only via oral communication with his colleagues. The discovery was acknowledged by Carl von Schreibers, director of the Vienna Mineral and Zoology Cabinet, who named th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herringbone Pattern
The herringbone pattern is an arrangement of rectangles used for floor tilings and road pavement, so named for a fancied resemblance to the bones of a fish such as a herring. The blocks can be rectangles or parallelograms. The block edge length ratios are usually 2:1, and sometimes 3:1, but need not be even ratios. The herringbone pattern has a symmetry of wallpaper group pgg, as long as the blocks are not of different color (i.e., considering the borders alone). Herringbone patterns can be found in wallpaper, mosaics, seating, cloth and clothing ( herringbone cloth), shoe tread, security printing, herringbone gears, jewellery, sculpture, and elsewhere. Examples Related tilings As a geometric tessellation, the herringbone pattern is topologically identical to the regular hexagonal tiling. This can be seen if the rectangular blocks are distorted slightly. In parquetry, more casually known as flooring, herringbone patterns can be accomplished in wood, brick, and tile. S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dazzle Camouflage
Dazzle camouflage, also known as razzle dazzle (in the U.S.) or dazzle painting, is a family of ship camouflage that was used extensively in World War I, and to a lesser extent in World War II and afterwards. Credited to the British marine artist Norman Wilkinson, though with a rejected prior claim by the zoologist John Graham Kerr, it consisted of complex patterns of geometric shapes in contrasting colours interrupting and intersecting each other. Unlike other forms of camouflage, the intention of dazzle is not to conceal but to make it difficult to estimate a target's range, speed, and heading. Norman Wilkinson explained in 1919 that he had intended dazzle primarily to mislead the enemy about a ship's course and so cause them to take up a poor firing position. Dazzle was adopted by the Admiralty in the UK, and then by the United States Navy. Each ship's dazzle pattern was unique to avoid making classes of ships instantly recognisable to the enemy. The result was that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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