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The Eye and Visual Pathways
Light Regulation
• Iris opens and closes the pupil – Allows light in– Protects eye from
light damage• Reflex• Light is then focused
by the lens
Retina and Photoreceptors
• Rods – more numerous, functions in dim light• Cones – color vision, found in the fovea
– 3 types – red, blue, & green
• Ganglion cells carry information to the optic nerve
Blindspot
The Human Eye
Cornea
Iris
Iris
Lens
Pupil
Vitreous Gel
Optic Nerve
Retina
Macula
Fovea
Visual Pathway • Right visual field is processed in the left hemisphere
• Medial retina crosses at the optic chiasm, lateral does not
• Info goes thru the thalamus– Most goes thru the
lateral geniculate nucleus
– Some first goes through the superior colliculus
Visual Processing• Message first goes to the occipital cortex• Dorsal – ‘where’ pathway
– Ends in parietal lobe
• Ventral – ‘what’ pathway– Ends in the temporal lobe– Color, shape, facial recognition