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Visual Processing
Sensory Neural Systems
5 February 2008
Rachel L. León
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/LabTutoria
ls/Vision/images/Rodcell.jpg
http://www.matossianeye.com/art2/ANATONY2.jpg
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/Lectures200
5/Visual%20pathways/Blk3Lec2.htm
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
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
Lateral Geniculate Nucleus
http://www.physics.utoledo.edu/~lsa/_color/17_eye.htm

LGN receives most
input from optic tracts

6 layer structure

Magnocellular layers

Parvocellular layers
Gross Dissection –
Human Visual Pathway
http://anatomy.uams.edu/
AnatomyHTML/atlas_htm
l/eye_38.html
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
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