Disorders of color and object recognition: syndromes of the ventral occipitotemporal pathway

Although lesions of the striate cortex are associated with hemifield defects, lesions of the inferior and medial occipitotemporal cortex often are associated with disorders of more high-level and complex visual processing. These disorders of the ventral processing stream can be considered as impairing the perception of color and recognition of objects, in contrast to the problems with motion and spatial localization seen with lesions of the dorsal occipitoparietal stream. Dysfunction in the ventral stream leads to the prototypic syndromes of achromatopsia, general visual agnosia, prosopagnosia, alexia without agraphia, and some forms of topographagnosia. Most of these are not single entities but families of disorders in which dysfunction in different cognitive and perceptual processes can lead to the same symptom. Continuum Lifelong Learning Neurol 2010;16(4):111-127.