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Hering's Law Of Equal Innervation
Hering's law of equal innervation is used to explain the conjugacy of saccadic eye movement in stereoptic animals. The law proposes that conjugacy of saccades is due to innate connections in which the eye muscles responsible for each eye's movements are innervated equally. The law also states that apparent monocular eye movements are actually the summation of conjugate version and disjunctive (or vergence) eye movements. The law was put forward by Ewald Hering in the 19th century, though the underlying principles of the law date back considerably. Aristotle had commented upon this phenomenon and Ptolemy put forward a theory of why such a physiological law might be useful. It was clearly stated for the first time by Alhacen in his '' Book of Optics'' (1021). Hering's law of equal innervation is best understood with Johannes Peter Müller's stimulus where an observer refoveates a point that moved in one eye only. The least-effort way to refoveate is to move the misaligned eye o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saccade
A saccade ( , French for ''jerk'') is a quick, simultaneous movement of both eyes between two or more phases of fixation in the same direction.Cassin, B. and Solomon, S. ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing Company, 1990. In contrast, in smooth pursuit movements, the eyes move smoothly instead of in jumps. The phenomenon can be associated with a shift in frequency of an emitted signal or a movement of a body part or device. Controlled cortically by the frontal eye fields (FEF), or subcortically by the superior colliculus, saccades serve as a mechanism for fixation, rapid eye movement, and the fast phase of optokinetic nystagmus. The word appears to have been coined in the 1880s by French ophthalmologist Émile Javal, who used a mirror on one side of a page to observe eye movement in silent reading, and found that it involves a succession of discontinuous individual movements. Function Humans and many animals do not look at a scene in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Book Of Optics
The ''Book of Optics'' ( ar, كتاب المناظر, Kitāb al-Manāẓir; la, De Aspectibus or ''Perspectiva''; it, Deli Aspecti) is a seven-volume treatise on optics and other fields of study composed by the medieval Arab scholar Ibn al-Haytham, known in the West as Alhazen or Alhacen (965–c. 1040 AD). The ''Book of Optics'' presented experimentally founded arguments against the widely held extramission theory of vision (as held by Euclid in his ''Optica''), and proposed the modern intromission theory, the now accepted model that vision takes place by light entering the eye.D. C. Lindberg (1976), ''Theories of Vision from al-Kindi to Kepler'', Chicago, Univ. of Chicago Press The book is also noted for its early use of the scientific method, its description of the camera obscura, and its formulation of Alhazen's problem. The book extensively affected the development of optics, physics and mathematics in Europe between the 13th and 17th centuries. Vision t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dissociated Vertical Deviation
Dissociated vertical deviation (DVD) is an eye condition which occurs in association with a squint, typically infantile esotropia. The exact cause is unknown, although it is logical to assume it is from faulty innervation of eye muscles. Presentation The eye drifts upward spontaneously or after being covered. The condition usually affects both eyes, but can occur unilaterally or asymmetrically. It is often associated with latent or manifest-latent nystagmus and, as well as occurring with infantile esotropia, can also be found associated with exotropias and vertical deviations. DVDs are usually controlled from occurring with both eyes open, but may become manifest with inattention. Usually some level of dissociative occlusion is required - to trigger the brain to suppress vision in that eye and then not control a DVD from occurring. The level of dissociative occlusion required may involve using a red filter, a darker filter or complete occlusion (e.g. with a hand). Onset DVD ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sherrington's Law Of Reciprocal Innervation
René Descartes (1596–1650) was one of the first to conceive a model of reciprocal innervation (in 1626) as the principle that provides for the control of agonist and antagonist muscles. Reciprocal innervation describes skeletal muscles as existing in antagonistic pairs, with contraction of one muscle producing forces opposite to those generated by contraction of the other. For example, in the human arm, the triceps acts to extend the lower arm outward while the biceps acts to flex the lower arm inward. To reach optimum efficiency, contraction of opposing muscles must be inhibited while muscles with the desired action are excited. This reciprocal innervation occurs so that the contraction of a muscle results in the simultaneous relaxation of its corresponding antagonist. A common example of reciprocal innervation, is the effect of the nociceptive (or nocifensive) reflex, or defensive response to pain, otherwise commonly known as the withdrawal reflex; a type of involuntary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Listing's Law
Listing's law, named after German mathematician Johann Benedict Listing (1808–1882), describes the Three-dimensional space, three-dimensional orientation of the human eye, eye and its rotation, axes of rotation. Listing's law has been shown to hold when the head is stationary and upright and gaze is directed toward far targets, i.e., when the eyes are either fixating, making saccades, or pursuing moving visual targets. Listing's law (often abbreviated L1) has been generalized to yield the ''binocular extension of Listing's law'' (often abbreviated L2) which also covers vergence. Definition Listing's law states that the eye does not achieve all possible 3D orientations and that, instead, all achieved eye orientations can be reached by starting from one specific "primary" reference orientation and then rotating about an axis that lies within the plane orthogonal to the primary orientation's gaze direction (line of sight / visual axis). This plane is called Listing's plane. It can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chameleon
Chameleons or chamaeleons ( family Chamaeleonidae) are a distinctive and highly specialized clade of Old World lizards with 202 species described as of June 2015. The members of this family are best known for their distinct range of colors, being capable of shifting to different hues and degrees of brightness. The large number of species in the family exhibit considerable variability in their capacity to change color. For some, it is more of a shift of brightness (shades of brown); for others, a plethora of color-combinations (reds, yellows, greens, blues) can be seen. Chameleons are distinguished by their zygodactylous feet, their prehensile tail, their laterally compressed bodies, their head casques, their projectile tongues, their swaying gait, and crests or horns on their brow and snout. Chameleons' eyes are independently mobile, and because of this there are two separate, individual images that the brain is analyzing of the chameleon’s environment. When hunting prey, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hermann Von Helmholtz
Hermann Ludwig Ferdinand von Helmholtz (31 August 1821 – 8 September 1894) was a German physicist and physician who made significant contributions in several scientific fields, particularly hydrodynamic stability. The Helmholtz Association, the largest German association of research institutions, is named in his honor. In the fields of physiology and psychology, Helmholtz is known for his mathematics concerning the eye, theories of vision, ideas on the visual perception of space, color vision research, the sensation of tone, perceptions of sound, and empiricism in the physiology of perception. In physics, he is known for his theories on the conservation of energy, work in electrodynamics, chemical thermodynamics, and on a mechanical foundation of thermodynamics. As a philosopher, he is known for his philosophy of science, ideas on the relation between the laws of perception and the laws of nature, the science of aesthetics, and ideas on the civilizing power o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johannes Peter Müller
Johannes Peter Müller (14 July 1801 – 28 April 1858) was a German physiologist, comparative anatomist, ichthyologist, and herpetologist, known not only for his discoveries but also for his ability to synthesize knowledge. The paramesonephric duct (Müllerian duct) was named in his honor. Life Early years and education Müller was born in Coblenz. He was the son of a poor shoemaker, and was about to be apprenticed to a saddler when his talents attracted the attention of his teacher, and he prepared himself to become a Roman Catholic Priest. During his college course in Koblenz, he devoted himself to the classics and made his own translations of Aristotle. At first, his intention was to become a priest. When he was eighteen, his love for natural science became dominant, and he turned to medicine, entering the University of Bonn in 1819. There he received his M.D. in 1822. He then studied at the University of Berlin. There, under the influence of Georg Hegel and Karl Ru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ibn Al-Haytham
Ḥasan Ibn al-Haytham, Latinized as Alhazen (; full name ; ), was a medieval mathematician, astronomer, and physicist of the Islamic Golden Age from present-day Iraq.For the description of his main fields, see e.g. ("He is one of the principal Arab mathematicians and, without any doubt, the best physicist.") , ("Ibn al-Ḥaytam was an eminent eleventh-century Arab optician, geometer, arithmetician, algebraist, astronomer, and engineer."), ("Ibn al-Haytham (d. 1039), known in the West as Alhazan, was a leading Arab mathematician, astronomer, and physicist. His optical compendium, Kitab al-Manazir, is the greatest medieval work on optics.") Referred to as "the father of modern optics", he made significant contributions to the principles of optics and visual perception in particular. His most influential work is titled '' Kitāb al-Manāẓir'' (Arabic: , "Book of Optics"), written during 1011–1021, which survived in a Latin edition. Ibn al-Haytham was an early propo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eye Movement (sensory)
Eye movement includes the voluntary or involuntary movement of the eyes. Eye movements are used by a number of organisms (e.g. primates, rodents, flies, birds, fish, cats, crabs, octopus) to fixate, inspect and track visual objects of interests. A special type of eye movement, rapid eye movement, occurs during REM sleep. The eyes are the visual organs of the human body, and move using a system of six muscles. The retina, a specialised type of tissue containing photoreceptors, senses light. These specialised cells convert light into electrochemical signals. These signals travel along the optic nerve fibers to the brain, where they are interpreted as vision in the visual cortex. Primates and many other vertebrates use three types of voluntary eye movement to track objects of interest: smooth pursuit, vergence shifts and saccades. These types of movements appear to be initiated by a small cortical region in the brain's frontal lobe. This is corroborated by removal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ptolemy
Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of importance to later Byzantine, Islamic, and Western European science. The first is the astronomical treatise now known as the ''Almagest'', although it was originally entitled the ''Mathēmatikē Syntaxis'' or ''Mathematical Treatise'', and later known as ''The Greatest Treatise''. The second is the ''Geography'', which is a thorough discussion on maps and the geographic knowledge of the Greco-Roman world. The third is the astrological treatise in which he attempted to adapt horoscopic astrology to the Aristotelian natural philosophy of his day. This is sometimes known as the ''Apotelesmatika'' (lit. "On the Effects") but more commonly known as the '' Tetrábiblos'', from the Koine Greek meaning "Four Books", or by its Latin equivalent ''Qua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
