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Topic: Visual cortex

Related Topics

cerebral cortex

adrenal cortex

Primary visual cortex

piriform cortex

visual cortex

cingulate cortex

entorhinal cortex

striate cortex

primary motor cortex

somatosensory cortex

prefrontal cortex

olfactory cortex

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	Visual cortex - Wikipedia, the free encyclopedia
		The name "striate cortex" is derived from the stria of Gennari, a distinctive stripe visible to the naked eye that represents myelinated axons from the lateral geniculate body terminating in layer 4 of the gray matter.
		Visual area V4 is one of the visual areas in the extrastriate visual cortex of the macaque monkey.
		Visual area V4 is not tuned for complex objects such as faces, as areas in the inferotemporal cortex are.
	en.wikipedia.org /wiki/Visual_cortex (3291 words)

	How is the Visual Cortex Organized?
		The visual cortex is part of the outermost layer of the brain, the cortex, and is located at the dorsal pole of the occipital lobe; more simply put, at the lower rear of the brain.
		Visual cortex is broken down into five areas, labelled V1, V2, V3, V4, and MT, which on occasion is referred to as V5.
		Selective injury of visual cortex in animal subjects is historically one of the most productive (and controversial) ways of investigating neural functioning, but in recent times we have developed tools to selectively deactivate or activate specific brain areas without harming them.
	www.wisegeek.com /how-is-the-visual-cortex-organized.htm (732 words)

	Webvision: Visual Cortex
		The human visual system can detect and discriminate between an incredibly diverse assortment of stimuli that may be chromatic or achromatic, in motion or not, pattered or unpatterned, two-dimensional or three.
		Visual input to the brain goes from eye to LGN and then to primary visual cortex, or area V1, which is located in the posterior of the occipital lobe.
		Maunsell JH, Gibson JR (1992) Visual response latencies in striate cortex of the macaque monkey.
	webvision.med.utah.edu /VisualCortex.html (9250 words)

	Research - Stimulation of Visual Cortex
		Restoration of vision, using a neuroprosthesis, depends upon providing the cortex with a well-controlled temporospatial electrical stimulation pattern that mimics the pattern of neural activity normally associated with vision, or uses the natural tuning properties of the visual system, to provide the cortex with meaningful sensory input.
		Our visual cortex does not compute images in terms of spots, or pixels; rather, images are represented in terms of edges, textures, colors, depths, and motion.
		By implanting microelectrodes within the visual cortex, with exposed tip sizes of the same order of magnitude as the neurons to be excited, much more selective stimulation, at lower stimulus currents, can, in principle, be achieved, resulting in more precise control of neuronal function.
	www.iit.edu /~npr/visualprosthesis2.htm (825 words)

	Central Visual Pathways
		As the signal is transmitted to upper layers of cortex, the information from the two eyes is mixed and binocular vision is created, but here in 4C the two eyes are still entirely separate.
		In the end, the parietal visual cortical areas (such as MT and PP) end up dealing with motion of objects, navigation through the world, and spatial reasoning (which is essentially moving things around in your head).
		Temporal visual areas (such as V4 and IT) are involved with the complex perception of patterns and forms as recognizable objects.
	thalamus.wustl.edu /course/cenvis.html (1728 words)

	Basic visual pathway
		Visual images are inverted as they pass through the lens.
		Therefore the left half of the brain is only interested in visual input from the right side of the world.
		Vision at the fovea is spared, perhaps because there is such a large representation of the fovea in the cortex, or perhaps due to overlapping blood supply.
	thalamus.wustl.edu /course/basvis.html (1099 words)

	Activity 2A: Visual Pathways
		The neurochemical signals are transmitted by nerve cells (ganglion cells) through the optic nerve to visual centers in the brain.
		In the visual projections, the images from both retinae are carried to the occipital lobes of the brain (these are in the back of the skull).
		If a defect occurs in the visual projec-tions or cortex, the visual field is cut in half and information is lost from only one side of the body (a condition called a homonymous hemianopsia).
	teachhealthk-12.uthscsa.edu /curriculum/vision-hearing/vision02a.htm (501 words)

	The Primary Visual Cortex
		The primary visual cortex is the part of the neocortex that receives visual input from the retina.
		For example, most cells in the visual cortex respond best to edges at some particular angle or the other (orientation preference) or to inputs from one eye or the other (ocular dominance).
		This was demonstrated in the cat visual cortex in a series of dramatic experiments.
	nn.cs.utexas.edu /web-pubs/sirosh/pvc.html (382 words)

	Visual Field Tester: Visual Prcessing
		Because so much visual processing is done here, this part of the brain is often called the visual cortex.
		The neurons of the cerebral cortex pass their separate analyses of the image on to other parts of the brain in the parietal and temporal lobes, where they are assembled and integrated with memory and emotion into a meaningful scene.
		Each side of the visual field is subdivided into an upper, middle, and lower "quadrant", as shown on the left.
	www.glyphic.com /free/fieldtester/VisualFieldTester1.html (654 words)

	The Cerebral Cortex
		Note: Extra-pyramidal motor cortex is widely distributed throughout cerebrum, though majority of contributions are from parietal and frontal lobes.
		Somatosensory cortex is highly organized by input source---and the body regions capable of the greatest sensitivity occupy the greatest amount of somatosensory cortex.
		The visual cortex of the occipital lobe is divided into layers which are involved in a "division of labor'..each receiving visual input and processing it somewhat differently, via projections to other cortical and subcortical regions.
	www.newmanveterinary.com /CerebralCortex.html (764 words)

	Synchronous Neural Activity in the Visual Cortex
		Investigations of this transition from asynchronous to synchronous firing showed that the onset of firing synchrony is always accompanied by a marked increase of the firing frequency.
		Therefore, we have proposed that achieving firing synchrony between neurons processing the same object might be a mechanism to increase the contrast between the object and its background.
		This general result implies that firing correlation does not depend on the specific characteristics of neurons in the visual cortex and, therefore, plays a role in a variety of related recognition and response tasks.
	www.ks.uiuc.edu /Research/Neural/synchronous.html (622 words)

	Study shows complexity of primate visual cortex - MIT News Office
		For decades, scientists believed that particular areas of the visual cortex in primate brains were each responsible for recognizing certain attributes of a viewed object, such as color or shape.
		Other areas in the visual cortex were similarly thought to perform other aspects of vision such as analysis of motion or depth perception-the "one area, one function" hypothesis.
		Scientists have identified more than 30 different areas in the visual cortex with at least 300 interconnections, indicating a complexity in visual processing that is only now being realized.
	web.mit.edu /newsoffice/1995/cortex-0816.html (551 words)

	Modeling of Neuronal Activity in the Visual Cortex
		From Blasdel (J. of Neuroscience 12, 1992), the optical imaging of the orientation hypercolumn structure in monkey visual cortex.
		Simple cells in the striate cortex respond to visual stimuli in an approximately linear manner, even though the LGN input to the striate cortex, and the cortical network itself, are highly nonlinear...
		In the primate visual pathway, orientation tuning of neurons is first observed in the primary visual cortex.
	www.math.nyu.edu /faculty/shelley/neuronal/neuronal_activity.html (1215 words)

	Global and local similarity of the primary visual cortex
		The core proposition is the existence of two, topographically identical mappings of the visual field to the primary visual cortex, which define the geometrical organisation of orientation preference and drive the formation of patchy connectivity in the supragranular layers.
		It has recently been shown, in the primary visual cortex of the tree shrew, that the patchy intrinsic connections are not perfectly radial, but form an elongated pattern (Bosking et al, 1997).
		CO blobs are assumed to be the central visual field's representation in the local maps of the supragranular layers.
	astronomy.swin.edu.au /~pbourke/papers/helnet (5995 words)

	Comparing Models of the Visual Cortex
		Important for this goal is an understanding of the principles underlying the structure of visual maps.
		Many cells in the mammalian primary visual cortex are selective to certain features in visual input.
		The lateral spatial pattern of orientation preference and ocular dominance in the striate cortex of an adult macaque as revealed by optical imaging.
	www.ks.uiuc.edu /Research/Neural/visual_cortex.html (1035 words)

	Function: Visual Pathway of the Eye
		Here, the left visual from one eye is combined with the other eye and the same goes for the right visual.
		Most visual impulses will travel directly from the lateral geniculate nuclei to the primiary visual cortex, also known as the striate cortex due to its many layers forming a striped appearance.
		From the prestriate cortex, visual signals enter the temporal lobes, located near the side of the head, for further and perhaps even more sophisticated processing.
	library.thinkquest.org /25607/functionVisualPathway.php3 (332 words)

	The Visual Cortex and Object Recognition
		The message passes from the retina down the optic nerve to structures in the mid brain and enters the cortex in a relatively small area called the primary visual cortex.
		They also found that the cells were organized in the cortex in a very systematic fashion, so that, for example, the message passes through a series of levels that analyze these lines in more and more complex ways, and that cells are lined up within the layers according to the orientation to which they respond.
		One theory that might seem logical is that at some later level of analysis, beyond the visual cortex, we have more complex cells that respond to objects like a face and a chair.
	web.umr.edu /~psyworld/object_recognition.htm (416 words)

	Lower Brain Activity In Visual Cortex Associated With Dyslexia (Site not responding. Last check: 2007-11-02)
		From the primary visual cortex they fan out and make connections at a number of secondary locations in the back of the brain devoted to processing visual information.
		Animal studies suggest that the M pathway is involved in fast visual processing and the control of eye movements, suggesting that an M cell deficiency might cause dyslexia by making it difficult for people to recognize rapidly scanned print or by interfering with the fine motor control of the eyes required for reading.
		-- non-dyslexics at the primary visual cortex or earlier in the visual pathway.
	www.pslgroup.com /dg/4930A.htm (1247 words)

	Visual system - Wikipedia, the free encyclopedia
		The psychological manifestation of visual information is known as visual perception.
		In the case of the camera, this medium is film or an electronic sensor; in the case of the eye, it is an array of visual receptors.
		Retinal is the fundamental structure involved in the transduction of light into visual signals, i.e.
	en.wikipedia.org /wiki/Visual (1640 words)

	rediff.com US edition: A new kind of vision
		Sur found that the ferrets had an auditory cortex that was wired in a manner similar to the visual cortex, and that they could see even with their auditory cortex.
		The visual cortex has a primary visual cortex that gets inputs from the visual part of the thalamus and the other cortical areas that get inputs from the primary visual cortex.
		What we have in these animals is a duplex visual pathway -- the retina to the visual thalamus to the visual cortex and the retina to the auditory thalamus to the auditory cortex.
	www.rediff.com /us/2000/jun/05us.htm (1447 words)

	ScienceDaily: Brain's Visual Cortex Doesn't "Tell" All It Knows
		The visual cortex lies in the rear of the cerebrum.
		Visual system -- The visual system is the part of the nervous system which allows organisms to see.
		Visual perception -- Visual perception is one of the senses, consisting of the ability to detect light and interpret (see) it as the perception known as sight or naked eye vision.
	www.sciencedaily.com /releases/2001/05/010529070018.htm (1998 words)

	Organization of the Visual Cortex in Human Albinism -- Hoffmann et al. 23 (26): 8921 -- Journal of Neuroscience (Site not responding. Last check: 2007-11-02)
		In A1, A2, A3, and A4, visual acuity was 0.5, 0.5, 0.2, and
		is that the abnormal representation of the ipsilateral visual
		Kaas JH, Guillery RW (1973) The transfer of abnormal visual field representations from the dorsal lateral geniculate nucleus to the visual cortex in Siamese cats.
	www.jneurosci.org /cgi/content/full/23/26/8921 (7094 words)

	UTCS Neural Nets Group Research: Visual Cortex
		The main idea is that the visual cortex is a continuously-adapting structure in a dynamic equilibrium with the external environment, and that lateral connections and synchronization of spiking activity are crucial to its behavior.
		Visual perceptual grouping is a process of identifying constituents that together form a group.
		These demonstrate how perception may be occurring in the adult cortex, with a level of detail not possible to achieve with current biological and psychophysical measurement methods.
	nn.cs.utexas.edu /pages/research/visualcortex.html (872 words)

	Modeling of orientation selectivity in the visual cortex
		Orientation selectivity is a remarkable property of neurons in the visual cortex which is supposed to provide the detection of local bars and edges in the processed visual images and encoding of their orientations (Hubel and Wiesel, 1962; 1974).
		According to the concept of columnar organization, the neighboring neurons in the visual cortex have similar orientation tunings and comprise an orientation column or iso-orientation domain (Hubel and Wiesel, 1974).
		Histograms of responses of three types of neurons in the guinea pig visual cortex (area V1) to the optimally (upper row) and non-optimally oriented (second and third rows) light bars and a diffuse stimulus (bottom row).
	www.rybak-et-al.net /iod.html (890 words)

	Visual Cortex Connects Visual Experience With Non-visual Events
		For years, neural activity in the brain's visual cortex was thought to have only one job: to create visual perceptions.
		The study, slated to appear in the March 17 issue of Science, implies that sensory parts of the brain may be able to accomplish more complex tasks than previously imagined, according to co-authors Marshall G. Shuler, MIT research affiliate, and Mark F. Bear, professor of brain and cognitive sciences.
		Electrodes were implanted in the visual cortex of adult rats.
	www.medicalnewstoday.com /medicalnews.php?newsid=39777 (439 words)

	ANU - The Centre for Visual Sciences (Site not responding. Last check: 2007-11-02)
		Rose and V.G. Dobson John Wiley and Sons, Chichester, U.K. 1985 Boyapati, J. and Henry, G.H. The character and influence of the claustral pathway to the striate cortex of the cat.
		1989 Thalluri, J. and Henry, G.H. Neurons of the striate cortex driven trans-synaptically by electrical stimulation of the superior colliculus.
		1991 Henry,G.H. and Vidyasagar,T.R. Evolution of the visual pathways in mammals.
	cvs.anu.edu.au /geoff/Publications.asp (1475 words)

	Neuroscience for Kids - Braille and the Brain
		For example, the occipital cortex is thought to be used mainly for visual processing.
		The researchers think it is possible that the traditionally visual areas might have been recruited for some other function, possibly for processing touch input they receive by reading with their hands.
		It may be more difficult for the visual cortex to adapt to another type of input if these neurons were originally dedicated to visual input.
	faculty.washington.edu /chudler/brail.html (481 words)

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