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Occipital Lobe
The occipital lobes are the center of our visual perception
system. They are not particularly vulnerable to injury because
of their location at the back of the brain, although any
significant trauma to the brain could produce subtle changes to
our visual-perceptual system, such as visual field defects and
scotomas. The Peristriate region of the occipital lobe is
involved in visuospatial processing, discrimination of movement
and color discrimination (Westmoreland et al., 1994). Damage to
one side of the occipital lobe causes homonomous loss of vision
with exactly the same "field cut" in both eyes. Disorders of the
occipital lobe can cause visual hallucinations and illusions.
Visual hallucinations (visual images with no external stimuli)
can be caused by lesions to the occipital region or temporal
lobe seizures. Visual illusions (distorted perceptions) can take
the form of objects appearing larger or smaller than they
actually are, objects lacking color or objects having abnormal
coloring. Lesions in the parietal-temporal-occipital association
area can cause word blindness with writing impairments (alexia
and agraphia) (Kandel, Schwartz & Jessell, 1991).
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