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Gaze (physiology)
The term gaze is frequently used in physiology to describe coordinated motion of the eyes and neck. The lateral gaze is controlled by the paramedian pontine reticular formation (PPRF). The vertical gaze is controlled by the rostral interstitial nucleus of medial longitudinal fasciculus and the interstitial nucleus of Cajal. Conjugate gaze The ''conjugate gaze'' is the motion of both eyes in the same direction at the same time, and conjugate gaze palsy refers to an impairment of this function. The conjugate gaze is controlled by four different mechanisms: * the saccadic system that allows for voluntary direction of the gaze * the pursuit system that allows the subject to follow a moving object * nystagmus Nystagmus is a condition of involuntary (or voluntary, in some cases) eye movement. Infants can be born with it but more commonly acquire it in infancy or later in life. In many cases it may result in reduced or limited vision. Due to the invol ... which includes both vestibu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physiology
Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical and physical functions in a living system. According to the classes of organisms, the field can be divided into medical physiology, animal physiology, plant physiology, cell physiology, and comparative physiology. Central to physiological functioning are biophysical and biochemical processes, homeostatic control mechanisms, and communication between cells. ''Physiological state'' is the condition of normal function. In contrast, ''pathological state'' refers to abnormal conditions, including human diseases. The Nobel Prize in Physiology or Medicine is awarded by the Royal Swedish Academy of Sciences for exceptional scientific achievements in physiology related to the field of medicine. Foundations Cells Although there are differ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paramedian Pontine Reticular Formation
The paramedian pontine reticular formation, also known as PPRF or paraabducens nucleus, is part of the pontine reticular formation, a brain region without clearly defined borders in the center of the pons. It is involved in the coordination of eye movements, particularly horizontal gaze and saccades. Input, output, and function The PPRF is located anterior and lateral to the medial longitudinal fasciculus (MLF). It receives input from the superior colliculus via the predorsal bundle and from the frontal eye fields via frontopontine fibers. The rostral PPRF probably coordinates vertical saccades; the caudal PPRF may be the generator of horizontal saccades. In particular, activity of the excitatory burst neurons (EBNs) in the PPRF generates the "pulse" movement that initiates a saccade. In the case of horizontal saccades the "pulse" information is conveyed via axonal fibres to the abducens nucleus, initiating lateral eye movements. The angular velocity of the eye during horizontal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rostral Interstitial Nucleus Of Medial Longitudinal Fasciculus
The rostral interstitial nucleus of medial longitudinal fasciculus (riMLF) is a portion of the medial longitudinal fasciculus which controls Gaze (physiology), vertical gaze. They project to the vestibular nuclei. External links * https://uni-tuebingen.de/uni/knl/Vilis/originof.htm * http://anatomy.umc.edu/faculty/lynch.html * https://web.archive.org/web/20091021004541/http://isc.temple.edu/neuroanatomy/lab/atlas/papc/ Brainstem {{Neuroanatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interstitial Nucleus Of Cajal
An interstitial space or interstice is a space between structures or objects. In particular, interstitial may refer to: Biology * Interstitial cell tumor * Interstitial cell, any cell that lies between other cells * Interstitial collagenase, enzyme that breaks the peptide bonds in collagen * Interstitial cystitis * Interstitium, the contiguous fluid-filled space existing between the skin and body organs * Interstitial fluid, a solution that bathes and surrounds the cells of multicellular animals * Interstitial granulomatous dermatitis * Interstitial infusion * Interstitial keratitis * Interstitial lung disease * Interstitial nephritis * Interstitial pregnancy Other uses To describe the spaces within particulate matter such sands, gravels, cobbles, grain, etc. that lie between the discrete particles. * Interstitial art * Interstitial condensation, in construction * Interstitial site, in chemistry * Interstitial defect, in chemistry * Interstitial television show, in televisio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conjugate Gaze Palsy
Conjugate gaze palsies are neurological disorders affecting the ability to move both eyes in the same direction. These palsies can affect gaze in a horizontal, upward, or downward direction. These entities overlap with ophthalmoparesis and ophthalmoplegia. Signs and symptoms Symptoms of conjugate gaze palsies include the impairment of gaze in various directions and different types of movement, depending on the type of gaze palsy. Signs of a person with a gaze palsy may be frequent movement of the head instead of the eyes. For example, a person with a horizontal saccadic palsy may jerk their head around while watching a movie or high action event instead of keeping their head steady and moving their eyes, which usually goes unnoticed. Someone with a nonselective horizontal gaze palsy may slowly rotate their head back and forth while reading a book instead of slowly scanning their eyes across the page. Cause A lesion, which is an abnormality in tissue due to injury or disease, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saccadic System
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 f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pursuit System
In the scientific study of vision, smooth pursuit describes a type of eye movement in which the eyes remain fixated on a moving object. It is one of two ways that visual animals can voluntarily shift gaze, the other being saccadic eye movements. Pursuit differs from the vestibulo-ocular reflex, which only occurs during movements of the head and serves to stabilize gaze on a stationary object. Most people are unable to initiate pursuit without a moving visual signal. The pursuit of targets moving with velocities of greater than 30°/s tends to require catch-up saccades. Smooth pursuit is asymmetric: most humans and primates tend to be better at horizontal than vertical smooth pursuit, as defined by their ability to pursue smoothly without making ''catch-up saccades''. Most humans are also better at downward than upward pursuit. Pursuit is modified by ongoing visual feedback. Measurement There are two basic methods for recording smooth pursuit eye movements, and eye movement in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nystagmus
Nystagmus is a condition of involuntary (or voluntary, in some cases) eye movement. Infants can be born with it but more commonly acquire it in infancy or later in life. In many cases it may result in reduced or limited vision. Due to the involuntary movement of the eye, it has been called "dancing eyes". In normal eyesight, while the head rotates about an axis, distant visual images are sustained by rotating eyes in the opposite direction of the respective axis. The semicircular canals in the vestibule of the ear sense angular acceleration, and send signals to the nuclei for eye movement in the brain. From here, a signal is relayed to the extraocular muscles to allow one's gaze to fix on an object as the head moves. Nystagmus occurs when the semicircular canals are stimulated (e.g., by means of the caloric test, or by disease) while the head is stationary. The direction of ocular movement is related to the semicircular canal that is being stimulated. There are two key form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optokinetic System
The optokinetic response is a combination of a slow-phase and fast-phase eye movements. It is seen when an individual tracks (pursuit movement) a moving object with their eyes, which then moves out of the field of vision, a point at which their eyes move back to the initial position (saccade movement) when they first saw the object. The reflex develops at about 6 months of age. Optokinetic nystagmus/response (OKN/R) is nystagmus that occurs in response to a visual stimulus on the retina. It is present in normally developed patients. The optokinetic response allows the eye to follow objects in motion when the head remains stationary (e.g., observing individual telephone poles on the side of the road as one travels by them in a car, or observing stationary objects while walking past them). Diagnosis Eliciting optokinetic nystagmus With normal vision, an OKN response develops in infants and remains through adulthood. The OKN response consists of initial slow phases in the directio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
