Pathophysiology
Visual agnosia occurs due to damage in the association areas of the visual cortex. The lateral occipital complex appears to respond to many different types of objects. Prosopagnosia (inability to recognize faces) is due to damage of the fusiform face area (FFA). Studies with functional imaging show that there is a certain area specialized for facial recognition, known as the fusiform face area, in the fusiform gyrus of the temporal lobe. However, this area is not exclusive to faces; recognition of other objects of expertise are also processed in this area. The extrastriate body cortex (EBA) was found to be activated by photographs, silhouettes, or stick drawings of human bodies. The parahippocampal place area (PPA) of the limbic cortex has been found to be activated by the sight of scenes and backgrounds. Cerebral achromatopsia (the inability to discriminate between different hues) is caused by damage to the V8 area of the visual association cortex. The left hemisphere seems to play a critical role in recognizing the meaning of common objects.
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