function of the superior colliculus

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Superior Colliculus Function - NayoungKwonBlogNeuroscientically Challenged is an educational website with articles of neuroscience, videos, images, a glossary and more. Where's the top colliculus? Back view of the brain stem showing the upper colliculi. There are two superior colliculi in the . They are placed symmetrically, one on each side of the ; they form two blows on the outer surface of the brain trunk. The superior colliculi are just below the two and above the two. The upper colliculus is often called optical tectum or tectum in nonhuman vertebrates. What is the top colliculus and what does it do? Although the full scope of the functions that can be attributed to the superior colliculi has not been completely delineated, it is understood that the superior colliculi are important to direct the behavioral responses to environmental stimuli. In other words, the top colliculus appears to be able to receive environmental information and then use that information to initiate a behavioral response appropriate to the current environmental context. For example, if you were sitting on the stairs in a baseball game and someone hit a home run, you would follow the ball with your head and eyes. This behavioral response to an environmental stimulus would involve the superior colliculi. In fact, the eye movements and heads like this are the most studied function of the upper colliculus, but the structure. The upper colliculus is composed of several layers of cells, which the anatomists have divided into what are called shallow and deep layers. The surface layers seem to receive mainly visual information from the and the , while the deep layers receive information from the auditory, visual and hearing systems. Deep layers also seem to be where the motor functions of the upper colliculus originate, such as .The different layers of the upper colliculi contain what are known as topographic maps for the information process. The term topographic map in neuroscience is used to refer to an organization where the sensory entry of a particular region of the body is sent to a specific area of the . For example, information from a particular part of the visual field is sent to a corresponding region of the surface layers of the upper colliculus. Because all layers of top colliculus have a similar topographical arrangement, it allows the rapid integration and improvement of signals that come through multiple modes of meaning (e.g. vision and hearing). Moreover, because the motor areas of the upper colliculus have the same topographic arrangement as the sensory areas, it allows the rapid initiation of motor responses to the incoming sensory information. In many other vertebrates (e.g. fish, birds), the top colliculus is one of the largest brain regions. In human beings this is not the case, as it is chained by several other structures. Despite its relatively small size, however, the top colliculus plays a very important role in integrating sensory information and rapidly triggering behavioral reactions to it. Reference (in addition to the text previously linked): King AJ. The Superior Colliculus. Current biology. 2004;14(9):R335-8. Neuroscientically Defied Neuroscientically The challenge is a resource of neuroscience learning. In addition to a blog that discusses current scientific events in a non-technical way, you will also find a series of videos and articles that you can use to learn about the basic principles of science and brain. SUBSCRIBEEnter your email address to receive new content by email: Delivered by TWITTEROTHER LINKS Unless otherwise indicated, all original images on this website are licensed under one.

Colliculus superiorSuperior colliculusDiagram of the superior colliculus (L) of the human (shown in red) and surrounding regions. The top colliculus is surrounded by a red ring and transparent red circle to indicate its location. Section through the middle brain at the upper colliculus level that shows the path of DetailsPart of IdentifiersColliculus ID superior[]The upper colliculus (for the "top hill") is a structure that is on the mammal. In non-mammalian, the structure is known as optical tectum, or optical lobe. The adjective form is commonly used for both structures. superior tectumoptic colliculusoptic lobe In mammals, the upper colliculus forms an important component of the middle brain. It is a structure paired and along with the forms paired the . The top colliculus is a layer structure, with a series of layers that varies by species. The layers can be grouped into the surface layers (and above) and the deepest layers left. Neurons in the surface layers receive direct entry from the retina and respond almost exclusively to visual stimuli. Many neurons in the deepest layers also respond to other modalities, and some respond to stimuli in multiple modalities. The deepest layers also contain a population of engine-related neurons, capable of activating eye movements, as well as other responses. The general function of the technical system is to direct behavioral responses to specific points in the egocentric space ("centered in body"). Each layer contains a surrounding world at coordinates, and the activation of neurons at a particular point on the map evokes a response to the corresponding point in space. In the primates, the top colliculus has been studied mainly with respect to its role in the direction of the eye movements. The visual entry of the retina, or the "comandada" entry of the cerebral cortex, creates a "bump" of activity on the technical map, which, if strong enough, induces to . Even in the primates, however, the top colliculus is also involved in the generation of spatially directed head turns, armor movements, and shifts in attention that do not imply overt movements. In other species, the top colliculus is involved in a wide range of responses, including the whole body becomes rats walking. In mammals, and especially primates, the massive expansion of the cerebral cortex reduces colliculus superior to a much lower fraction of the entire brain. However, it remains important in terms of function as the main integrator center for eye movements. In non-mammal species, optical tectum is involved in many responses including swimming in fish, flying in birds, tongue strikes to prey in frogs, and snakes in snakes. In some species, including fish and birds, optical tectum, also known as the optical lobe, is one of the largest components of the brain. Note on terminology: This article follows the terminology established in literature, using the term "superior colliculus" when discussing mammals and "optical computer" when non-mammal species or vertebrates are discussed in general. ContentsStructure[] The upper colliculus is a layer synaptic structure. The two superior colliculi sit under it and surround it in the . Understand the look of the , after the e immediately superior to the . The lower and higher colliculi are collectively known as the (latins, quadruple bodies). The higher colliculi are larger than the lower colliculi, although the lower colliculi are more prominent. The upper colliculus brachio (or upper brachio) is a branch that extends laterally from the upper colliculus, and, passing between it and , is partly continued in an eminence called the , and partly in the . colliculussuperior brachium superior The top colliculus is associated with a nearby structure called parabigeminal core, often known as its satellite. In optical tectum, this nearby structure is known as the isthmi core. parabigeminal nucleusThe neuronural circuit[]The microstructure of the upper colliculus and the optical tectum varies according to the species. As a general rule, there is always a clear distinction between surface layers, which receive inputs mainly from the visual system and mainly show visual responses, and deeper layers, which receive many types of input and project to numerous brain areas related to the engine. The distinction between these two areas is so clear and consistent that some anatomists have suggested that separate brain structures be considered. In mammals, neuroanatomists conventionally identify seven layers The top three layers are called superficial: Lamina ISZLamina IISGSLamina IIINext see two intermediate layers: Lamina IVSGILamina VSAIFinally come the two deep layers: Lamina VISGPLamina VIISAP The surface layers receive mainly retinal inputs, areas related to the vision of the cerebral cortex, and two technic-related structures called the parabigeminal core. The retina entry covers the entire surface area, and is bilateral, although the counterlateral portion is more extensive. The cortical input comes more strongly from (area 17), the secondary visual cortex (areas and ), and the . The parabigeminal core plays a very important role in the technical function described below. Unlike the inputs dominated by vision to the surface layers, the intermediate and deep layers receive inputs from a very diverse set of sensory and motor structures. Most of the areas of the brain cortex project to these layers, although the entry of the "association" areas tends to be heavier than the entry of primary sensory areas or motors.[] However, the cortical areas involved, and the strength of their relative projections differs through the species. Another important entry comes from the , , a component of the . This projection uses the inhibiting neurotransmitter, and it is thought to have a "gating" effect on the upper colliculus. The intermediate and deep layers also receive the entry of the , which transmits the somatosensor information of the face, as well as the , , , , and . In addition to its distinctive inputs, the surface and deep areas of the upper colliculus also have distinctive products. One of the most important exits goes to the intermediate and lateral areas of the thalamus, which in turn project to the areas of the cerebral cortex that are involved in the control of the eye movements. There are also projections from the surface area to the pretectal nuclei, the thalamus and the parabigeminal nucleus. The projections of the deepest layers are more extensive. There are two large descending pathways, which travel to the brain trunk and spinal cord, and numerous projections ascending to a variety of sensory centers and engines, including several that are involved in generating eye movements. Both colliculi also have projections descending to the paramedian pontine reticular formation and the spinal cord, and therefore they may be involved in quicker stimuli responses than the cortical processing would allow. Mosaic structure[]In the detailed examination the collicular layers are not actually smooth leaves, but divided into a discrete column panal arrangement. The clearest indication of the spinal structure comes from the cholinergical inputs that emerge from the parabigeminal nucleus, whose terminals form evenly spaced clusters that extend from top to bottom of . Several other neurochemical markers, including calretinin, parvalbumin, GAP-43 and NMDA receptors, and connections with many other brain structures in the brain trunk and dience also show an infamousness. The total number of columns has been estimated at around 100. The functional meaning of this columnar architecture is not clear, but it is interesting that the recent evidence has involved the cholinergic inputs as part of a recurring circuit producing winning dynamics-all within the tectum, as described in more detail below. All species that have been examined, including mammals and non-mammals, show compartimenization, but there are some systematic differences in the details of the arrangement. In species with a narrow type retina (mainly species with laterally placed eyes, such as rabbits and deer), the compartments cover the entire extension of the SC. In species with centralized fovea, however, the compartimentation is broken down on the front (roster) of the SC. This part of the SC contains many neurons "fixation" that continuously shoot while the eyes remain fixed in a constant position. Function[] The history of optical tectum research has been marked by several major changes of opinion. Before about 1970, most studies involved non-mammals — fish, frogs, birds — that is, species in which optical tectum is the dominant structure that receives eye entry. The general vision was then that optical tectum, in these species, is the main visual center in the non-mammal brain, and, as a consequence, is involved in a wide variety of behaviors[]. However, from the 1970s to 1990, the neuronal recordings of mammals, mainly monkeys, focused mainly on the role of the superior colliculus in controlling eye movements. This line of research came to dominate literature to such an extent that the majority view was that eye movement control is the only important function in mammals, a vision still reflected in many current textbooks. However, at the end of the 1990s, the experiments that used animals whose heads were free to move clearly showed that the SC produces shifts of gaze, usually composed of combined movements of head and eye, instead of eye movements per se. This discovery revived interest in the magnitude of the functions of the superior colliculus, and led to studies of a variety of species and situations. However, the role of the SC in controlling eye movements is understood in depth far greater than any other function. Behavioral studies have shown that the SC is not necessary for the recognition of objects, but plays a critical role in the ability to direct behaviors towards specific objects, and can support this ability even in the absence of the cerebral cortex. Thus, cats with the greatest damage to the visual cortex cannot recognize objects, but they can follow and orient themselves to mobile stimuli, although more slowly than usual. However, if a half of the SC is removed, the cats will constantly circulate towards the side of the injury, and will compulsively guide the objects located there, but will not guide at all the objects located in the opposite hemifield. These deficits decrease over time but never disappear. Eye movements[] In the primates, it can be divided into several types: , in which the eyes are directed towards an immobile object, with eye movements only to compensate the movements of the head; , in which the eyes are constantly moving to track an object in motion; , in which the eyes move very quickly from place to place; and , in which the eyes move simultaneously in opposite directions to hold a unique eye. The superior colliculus is involved in all of these, but its role in the saccades has been studied with greater intensity. Each of the two colliculi, one on each side of the brain, contains a two-dimensional map that represents half of the field of view. The — the highest sensitivity region — is represented on the front edge of the map, and the periphery on the rear edge. Eye movements are evoked by activity in the deep layers of the SC. During the fixation, the neurons close to the front edge — the foveal area — are tonicately active. During smooth search, neurons are activated a small distance from the front edge, which leads to small eye movements. For the saccades, neurons are activated in a region that represents the point to which the saccada will be directed. Just before a saccada, the activity quickly accumulates in the destination location and decreases in other parts of the SC. The encoding is quite broad, so for any saccada given the activity profile forms a "bone" that encompasses a substantial part of the collicular map: The location of the peak of this "hill" represents the goal of the saccade. The SC encodes the objective of a change of sight, but does not seem to specify the precise movements necessary to get there. The decomposition of a gaze becomes movements of head and eye and the precise trajectory of the eye during a sacchain depend on the integration of collicular and non-collicular signals by the motor zones downstream, in ways that are not yet well understood. Regardless of how the movement is evoked or performed, the SC encodes it in "retinotopian" coordinates: that is, the location of the SC 'hill" corresponds to a fixed location in the retina. This seems to contradict the observation that the stimulation of a single point in the SC can result in different directions of change of look, depending on the initial eye orientation. However, it has been shown that this is because the retina location of a stimulus is a non-linear function of destination location, eye orientation and spherical geometry of the eye. There has been some controversy about whether the SC simply orders the eye movements, and leaves the execution to other structures, or if it actively participates in the performance of a saccada. In 1991, Munoz et al., on the basis of the data they collected, argued that during a sacchain, the "son" of the activity in the SC is gradually moved, to reflect the changing compensation of the eye from the place of destination while the saccade advances. At present, the prevailing view is that, although the "hilo" moves slightly during a sacchain, it does not change in a stable and proportional way that the hypothesis "moving hill" predicts. However, moving hills can play another role in the upper colliculus; more recent experiments have demonstrated a hill continually moving from the activity of visual memory when the eyes move slowly while maintaining a separate goal of saccade. The output of the SC's motor sector goes to a set of brain and brain cores, which transform the "place" code used by the SC in the "value" code used by oculomotor neurons. Eye movements are generated by six muscles, arranged in three pairs orthogonally aligned. Thus, at the level of the final common path, the eye movements are essentially encoded in a cartesian coordinate system. Although the SC receives a strong entry directly from the retina, in primates it is under the control of the cerebral cortex, which contains several areas that are involved in determining eye movements. The , a part of the motor cortex, are involved in triggering intentional saccades, and an adjacent area, the complementary eye fields, are involved in organizing groups of saccades in sequences. Parietal eye fields, beyond the brain, are mainly involved in reflective saccades, made in response to changes in the sight. The SC only receives inputs in its surface layers, while the deeper layers of colliculus also receive hearing and somatosensory inputs and are connected to many sensory areas of the brain. It is thought that colliculus as a whole helps to guide the head and eyes towards something seen and heard. The upper colliculus also receives hearing information from the lower colliculus. This hearing information is integrated with the visual information already present to produce the ventrilocuum effect. Disability[]As with eye movements, the SC seems to have an important role to play in circuits that support distraction. Alisada distraction occurs in normal aging and is also a central feature in several medical conditions, including (ADHD). Research has shown that lesions to the SC in several species can result in greater distraction and, in humans, the elimination of inhibitive control in the prefrontal cortex SC, so increasing activity in the area also increases distraction. Research in an animal model of ADHD, the spontaneously hypertensive rat, also shows altered collicular behaviors and physiology. In addition, amphetamine (main treatment for ADHD) also suppresses colliculus activity in healthy animals. Other animals[] Other mammals[]Primates[] It is generally accepted that the top colliculus is unique among , since it does not contain a full map of the visual field seen by the side eye. On the other hand, like the and, each colliculus represents only the contralateral half of the , up to the middle line, and excludes a representation of the ipsilateral half. This functional feature is explained by the absence, in primates, of anatomical connections between the temporary half of the upper and contralateral colliculus. In other mammals, the lymph node cells retinate throughout the counterlateral project of retina to the colliculus contralateral. This distinction between primates and non-primatoes has been one of the key lines of evidence in support of the proposal by the Australian neuroscientist in 1986, after discovering that the flying foxes () resemble the primates in terms of the pattern of anatomical connections between the retina and the superior colliculus. Cats[]In the cat the top colliculus projects through it and interacts with the motor neurons in the . Bats are not, in fact, blind, but depend much more on ecolocalization than the vision of navigation and catching of prey. They get information about the surrounding world emitting sound chirps and then hear the echoes. Your brains are highly specialized for this process, and some of these specializations appear in the upper colliculus. In bats, the retina projection occupies only a thin area just below the surface, but there are extensive entrances of hearing areas, and exits to motor areas capable of guiding the ears, head or body. The echoes from different directions activate neurons in different locations in the collicular layers, and the activation of collicular neurons influences the chiropes that emit bats. Therefore, there is a strong case that the superior colliculus performs the same type of functions for hearing behaviors guided by bats it performs for the visual guided behaviors of other species. Bats are usually classified into two main groups: (the most numerous and commonly found throughout the world), and (the fruit bats found in Asia, Africa and Australasia). With an exception, do not echo and build on a developed sense of vision to navigate. The image of the neurons in the top colliculus in these animals forms a precise map of the , similar to that found in and . Rodents[]The superior colliculu in rodents has been hypothesized to mediate sensory approaches and avoidance behaviors. Studies using circuit analysis tools in the top colliculus of the mouse have revealed several important functions. Non-mammal vertebrates[]Optical Tectum[] He is the visual center of the non-mammal brain that develops from the mesencephalon. In non-mammals the connections of optical tectum are important for the recognition and reaction to various objects of size that is facilitated by excitatory optical nervous transmitters like . The visual experience that goes beyond the beginning of development produces a change in technical activity. The changes in the technical activity led to an inability to hunt and capture successfully prey. Hypothalamus's inhibitive signaling to deep tech is important in processing tectal in cebrafish larvae. The techntal neuropyla contains structures that include axons and dendritos. The neuropyla also contains superficial inhibitory neurons located in . Instead of a large cerebral cortex, the zebra fish has a relatively large optical tectum that is hypothesized to carry out part of the visual processing that the cortex performs in mammals. Recent studies of lesions have suggested that optical tectum has no influence on the movement responses of greater order as or , but it can be more integral to the lower order cues in the perception of movement as in the identification of small objects. Optical tectum is one of the fundamental components of the , existing through a range of species. Some aspects of the structure are very consistent, including a structure composed of a series of layers, with a dense input of the optical pathways to the surface layers and another strong input that transmits the somatosensori entry to deeper layers. Other aspects are very variable, such as the total number of layers (from 3 in the African lung fish to 15 in the golden fish), and the number of different types of cells (from 2 in the lung fish to 27 in the house sparrow). Optical tectum is closely associated with an adjacent structure called the isthmi core, which has attracted a lot of interest because it obviously makes a very important contribution to the technical function. (In the upper colliculu, the similar structure is called the parabigeminal nucleus.) The isthmii nucleus is divided into two parts, called isthmus pars magnocellularis (Imc; "part with large cells") and isthmus pars parvocellularis (Ipc; "part with small cells"). The connections between the three areas — optical tectum, Ipc and Imc— are topographical. Neurons in the surface layers of the optical tectum project to the corresponding points in the Ipc and Imc. The projections for the Ipc are very focused, while the projections for the Imc are somewhat more diffuse. Ipc gives rise to well-focused colinergic projections both to Imc and optical tectum. In the optical tectum, the cholinergicas inputs of Ipc branch to give rise to terminals that extend through a whole column, from top to bottom. Imc, on the other hand, gives rise to GABAergic a tectum Ipc and optical projections that spread widely in the lateral dimensions, which encompass most of the retinotopian map. Therefore, the tectum-Ipc-Imc circuit causes the technical activity to produce recurrent feedback that implies adjusted excitation of a small column of neighboring tectal neurons, along with the global inhibition of distant tectal neurons. nucleus isthmiImcIpc Optical Tectum is involved in many responses, including swimming in fish, flying in birds, tongue strikes in frogs, and fang-strikes in snakes. In some species, including fish and birds, optical tectum, also known as the optical lobe, is one of the largest components of the brain. In hagfish, lamprey, and shark is a relatively small structure, but in fish it expands greatly, in some cases becoming the largest structure of the brain. In amphibians, reptiles, and especially birds, it is also a very significant component. In which you can detect , as and , the initial neural entry is through the one instead of the . The rest of the processing is similar to that of the visual sense and therefore implies optical tectum. Fish[]Lamprey[]He has been widely studied because he has a relatively simple brain that is thought of in many ways to reflect the brain structure of early vertebrate ancestors. Since the 1970s, Sten Grillner and his colleagues at the Stockholm Karolinska Institute have used the lampre as a model system to develop the fundamental principles of motor control in vertebrates, starting in the spinal cord and working up in the brain. In a series of studies, they found that the neuronal circuits within the spinal cord are able to generate the rhythmic motor patterns that underlie swimming, that these circuits are controlled by specific locomotive areas in the brain trunk and midbrain, and that these areas in turn are controlled by higher brain structures, including the and the tectum. In a study of the tectum of luminosity published in 2007, they found that electrical stimulation could cause eye movements, lateral folding movements, or swimming activity, and that the type, amplitude and direction of movement varied as a function of the location within the tectum that was stimulated. These findings were construed as consistent with the idea that tectum generates locomotive directed by targets in the lampre as it does in other species. Birds[ ]In the birds the optical tectum is involved in the flight and is one of the largest brain components. The study of avian visual processing has allowed greater understanding of that in mammals, including humans. See also[]Additional images[]Schema that shows the central connections of the optical and pathways. (Superior colliculus visible near the center.) Upper colliculu Brain. Later view. Notes[]ab3337abab1251abab8311653215ab30327420813071102789112325abc2963References[]41925123441991122489443846013410332514223114297879142112191051780 External links[] Wikimedia Commons has media related to . ########################################################################################################################################################################################################################################################## : Sensory/ascendence : Motor/descendence (Ventral): Sensory/ascendant : Motor/descendence : : Base: Motor/descending : Surface Surface : Sensory/ascendence : Motor/descendence : Sensory/ascendence : Motor/descendence : : Base: Motor/descending : Surface : Sensory/ascendence : Motor/descendence : : : Motor/descendence : Surface Navigation menu Personal tools Named spaces Variants Views More Search Navigation Contributed Tools Printing/exporting Other projects Languages

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