1. The Eye and Visual
Pathways

2. Light Regulation
• Iris opens and
closes the pupil
– Allows light in
– Protects eye from
light damage
• Reflex
• Light is then focused
by the lens

3. 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

4. Blindspot

5. The Human Eye
Vitreous Gel
Iris
Optic Nerve
Cornea
Macula Pupil
Fovea
Lens
Retina Iris

6. 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

7. 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