404 Neuroanatomy: Draw It to Know It
Cortical Visual Processing (Advanced ) (Cont.)
Now, in the lateral hemisphere diagram, in the lateral
occipital cortex, anterior to V4, label the lateral occipital
complex. Th is area responds disproportionately strongly
for object recognition. It displays perceptual constancy,
meaning an object can be recognized equally well regard-
less of such properties as object viewpoint, size, or illu-
mination; it also displays form-cue invariance, meaning ,
for example, that an object is equally identifi able whether
it is viewed in the form of a drawing or a photograph.^26
Next, label the fusiform face area within the right, lat-
eral posterior fusiform g yrus; the fusiform face area is
the most well-studied area for facial processing, but
additional facial processing centers for diff erent attri-
butes of facial recognition do exist — they include the
occipital face area as well as a region of the superior tem-
poral sulcus. Also, note that a longstanding debate is
whether the fusiform face area is specifi c for the recogni-
tion of human faces or whether it responds to any over-
trained visual stimulus (eg, cars in car salesmen or birds
in bird-watchers). As a clinical corollary, injury to the
fusiform face area can result in prosopagnosia: a defi cit
for the recognition of familiar faces (ie, friends and
family).^27
Now, show that non-face body parts are processed
separate from faces, most notably, in the extrastriate
body area in the lateral occipitotemporal cortex. When
we view a human fi gure, the person’s face and body
are projected onto the retina contiguously, as they are
perceived in the visual world, and they maintain this
contiguous relationship when they are projected to the
primary visual cortex and, presumably, as they step
through the secondary and tertiary visual cortices. But
for higher-level visual processing, at least in part, the
body is separated from the face and is processed near the
V5 motion-sensitive area (discussed next), presumably
because of the relationship between body parts and move-
ment. Note, however, that just as multiple centers for
facial processing exist, so, too, multiple body part analysis
centers also exist, such as the fusiform body area.^22 , 28
Next, show that the processing of places lies within
the parahippocampal place area, which lies within the
posterior parahippocampal and anterior lingual cortices.
Th e parahippocampal place area responds to environ-
mental scenes and buildings. Injury to the parahip-
pocampal place area can potentially cause landmark
agnosia, which is the inability to recognize fundamental
navigation landmarks: for example, one’s own house.
Landmark agnosia is oft en categorized under the more
broad clinical phenomenon of topographic disorienta-
tion, which is the inability to fi nd one’s way through an
environment, because patients with landmark agnosia
naturally have substantial navigational disorientation.
Note, also, that the parahippocampal place area is
separate from the parietal dorsal stream area, which is
responsible for encoding orientation of the body in
space.^26 , 29 – 32