PSY 448 Clinical Neuropsychology	Last revised: Sept. 28, 2021
Occipital Lobe Lesions: Behavioral Deficits

Material in this handout summarizes materials from Kolb & Whishaw (2003), pp. 328-338
It is representative, rather than comprehensive in coverage.

Some types of impairments due to occipital and associated region lesions
Blindsight (perceiving locations but not content of visual objects) [YouTube 0.39] Achromatopsia (color blindness) [examples] Motion blindness-Stillness sight (akinopsia) Visual agnosia: inability to combine individual parts of an object together to recognize the entire object (YouTube 5.26) Apperceptive agnosia: inability to recognize overall or basic shape of objects (damage to lateral occipital areas toward ventral stream). Often due to carbon monoxide poisoning which kills tissue in the "watershed" regions--border areas between arterial supplies Associative agnosia: inability to recognize objects despite perception of overall shape (damage along ventral stream anterior to occipital lobe) Visual-form agnosia: inability to recognize objects based on drawings Prosopagnosia: inability to recognize faces including their own. Most can tell difference between human and nonhuman faces as well as identify emotional expression. (Damage bilaterally beneath calcarine fissue near junction with temporal lobe) (YouTube 3.30 Oliver Sacks on Face Blindness 5.04)
Visual Field Defects
hemianopia = blindness in half the visual field quadrantanopia = blindness in one quadrant of the visual field scotoma = a small blind spot