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Understanding the Visual Processing Neural Systems

This review provides an overview of visual processing within the sensory neural systems, focusing on the structure of the eye, the role of sensory cells, and retinal processing. It discusses neural coding in the retina, emphasizing ganglion cells, receptive fields, and mechanisms like lateral inhibition that enhance visual boundaries. The classical visual pathway is outlined, detailing the organization of the optic nerves, lateral geniculate nuclei, and the primary visual cortex. Additional visual pathways beyond the LGN, including connections to the superior colliculus and pulvinar, are also explored.

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Understanding the Visual Processing Neural Systems

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  1. Visual Processing Sensory Neural Systems 5 February 2008 Rachel L. León

  2. Review • Basic eye structure • Sensory cells of the eye • Retinal processing http://scienceblogs.com/clock/2006/06/bio101_lecture_6_physiology_re.php http://www.chemistry.wustl.edu/~edudev/LabTutorials/Vision/images/Rodcell.jpg http://www.matossianeye.com/art2/ANATONY2.jpg

  3. Neural Coding in the Retina • Ganglion cells influenced by many receptors • Pattern of illumination that maximally excites ganglion cell is doughnut shaped • Center-surround receptive field • Lateral inhibition of receptive fields enhances boundaries • X, Y, W ganglion cells http://www.neurobio.arizona.edu/282/Lectures2005/Visual%20pathways/Blk3Lec2.htm

  4. Outline • Classical Visual Pathway • Organization of optic nerves and tracts • Lateral geniculate nuclei • Primary visual cortex • Other Pathways http://www.nature.com/nrn/journal/v6/n3/fig_tab/nrn1630_F4.html

  5. Optic Nerve and Tract • Temporal retinal fibers maintain ipsilateral position • Nasal retinal fibers cross at optic chiasm • Optic tract contains all information from contralateral visual field http://library.thinkquest.org/26313/eye_wo1.jpg

  6. Lateral Geniculate Nucleus • LGN receives most input from optic tracts • 6 layer structure • Magnocellular layers • Parvocellular layers http://www.physics.utoledo.edu/~lsa/_color/17_eye.htm

  7. Gross Dissection – Human Visual Pathway http://anatomy.uams.edu/AnatomyHTML/atlas_html/eye_38.html

  8. Primary Visual Cortex • Simple cells vs. Complex cells • Cortical orientation columns • Ocular dominance columns • Blobs – receive parvocellular input http://www.neurobio.arizona.edu/282/Lectures2005/Visual%20pathways/10_022.jpg

  9. Other Visual Pathways • Most of the axons not going to LGN terminate in superior colliculus • Some efferents from SC go to pulvinar • Pulvinar efferents terminate in visual cortex other than V1 • Some optic tract axons terminate in pretectal area

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