Agnosias

Question 1

Agnosia

Answer 1

Rare neuropsychological symptom; failure of recognition

Question 2

Apperceptive agnosia

Answer 2

Impairment in perceptual processing, prevents recognition

Question 3

Narrow apperceptive agnosia

Answer 3

Adequate elementary visual functioning but inability to recognize, match, copy, or discriminate simple visual forms (via CO poisoning, mercury intoxication, bilateral PCA stroke)

Question 4

Dorsal Simultanagnosia

Answer 4

patient unable to appreciate the meaning of a whole picture or scene even though the individual parts are well-recognized (luria: inability to attend to more than one object at a time); found in damaged bilateral parieto-occipital damage, damaged superior occipital, damaged inferior parietal, or generalized/local degenerative disease; impaired on counting tasks

Question 5

Balint syndrome

Answer 5

psychic paralysis of fixation with an inability to voluntarily look into the peripheral field; optic ataxia (clumsiness or inability to respond to visual stimuli); disturbance of visual attention mainly affecting the periphery of the visual field resulting in concentric narrowing of effective field

Question 6

Repetition Blindness

Answer 6

when visual or auditory stimuli are presented in rapid succession, the second instance of a stimulus will sometimes not be seen/heard if it occurs within 80-150 ms of the first presentation

Question 6

Ventral Stimultanagnosia

Answer 6

lesions restricted to the left occipitotemporal junction; succeed on dot-counting tasks, less impaired in negotiating natural environ; all presenting as letter-by-letter readers

Question 7

Perceptual Categorization Deficit

Answer 7

unilateral posterior right hemisphere lesions; have difficulties matching different view of 2- or 3-dimensional objects

Question 8

Associative Visual Agnosia

Answer 8

presence of a modality-specific object identification defect in the context of preserved ability to copy and/or match; patients cannot name seen objects and typically fails when asked to demo semantic knowledge about the stimulus or its functional properties; associated with prosopagnosia, color agnosia, alexia

Question 9

Optic Aphasia

Answer 9

the patient is unable to name visually presented objects but is able to show recognition by indicating its use, pointing to it when it is named, or otherwise demonstrating knowledge of object meaning; seen in left PCA infarct

Question 10

Nonoptic Aphasia

Answer 10

patients who can name visually presented stimuli but cannot name the same objects when given a definition or demonstrate/describe the use of the objects

Question 11

Central Achromatopsia/Dyschromatopsia

Answer 11

causative lesions can be in optic nerve, chiasm, or one/both cerebral hemispheres, can be hemianopic or in whole visual field; unilateral/bilateral lesions in inferior ventromedial sector of occiptal lobe involving lingual and fusiform gyri; single area in each hemisphere controls color processing for entire hemifield

Question 12

Color Agnosia/Amnesia

Answer 12

existence of internal color space that stores abstract mental representations of color; some patient have defects in categorizing colors despite the ability to perceptually discriminate them (color naming could be intact)

Question 13

Color Anomia

Answer 13

patient can match and name colors from memory but is unable to name visualized colors (visual-verbal task); often associated with alexia without agraphia

Question 14

Specific Color Aphasia

Answer 14

differ from color anomics in their poor performance on verbal-verbal color tasks; aphasic symptoms usually present but difficulty with colors unusually severe; can sort and match colors

Question 15

Prosopagnosia

Answer 15

inability to recognize previously familiar faces; primary defect is in identifying and recognizing whose face they are viewing; associated neuropsych deficits include central achromatopsia, constructional disability, topographical memory loss, dressing apraxia

Question 16

Capgras Syndrome

Answer 16

patient believes that familiar persons have been replaced by imposters