Visual system Flashcards
Lesions of the optic chiasm result in
Bitemporal hemianopia
LH damage vs. RH damage effects on block design
LH - error with internal details, tend to recognize when incorrect RH - break configuration but see internal details, do not appreciate when incorrect, may skew to right space
Palinopsia
Persistence or reappearance of a recently viewed object; assoc. w/ parietal & occipital lobe lesions
Akinetopsia
Acquired cerebral motion blindness
A lesion of the optic nerve results in
Monocular visual loss or monocular scotomas
Clinical triad of Balint’s syndrome
Simultanagnosia, optic ataxia, ocular apraxia
Metamorphopsia
Condition in which objects have distorted shape & size; aka “Alice in Wonderland” syndrome Associated with disorders of the inferior or lateral visual association cortex
Formed visual hallucinations arise from
Inferior temporo-occipital visual association cortex
How is the pretectum involved in vision?
Changes in pupil size in response to light
Meyer’s loop
Inferior optic radiations that arc forward into the temporal lobe; carry info from the inferior retina or superior visual field
Cortical blindness
Caused by bilateral lesions to the primary visual cortex
Common causes of optic chiasm lesions
Pituitary adenoma, meningioma, craniopharyngioma, hypothalamic glioma
Lesions of the LGN result in
Contralateral homonymous hemianopsia
LH damage vs. RH damage effects on drawing
LH - drawing is spatially correct but oversimplified with omission of details RH - fragmented drawing, may have details but lost whole & spatial relations, may neglect L side
Macula
Oval region that surrounds the fovea
Info from the fovea is represented by what portion of fibers in the topic nerve?
~1/2
Blindsight
Despite lesions of the primary visual cortex & lack of conscious visual perception, some patients are able to perform tasks, appears to depend on info that is transmitted via extrageniculate visual pathways
Face/object recognition is localized to the
Midportion of the fusiform gyrus
The retina is supplied by what artery?
Ophthalmic
Anton’s syndrome
Syndrome in which patients with cortical blindness deny blindness & confabulate visual images
Dorsal visual stream
“where”, info regarding spatial analysis & orientation; runs along top side of cerebrum from occipital to parietal visual areas
An inability to recognize facial emotion is associated with lesions to the
Bilateral amygdala
Lesions of the lower/upper optic radiations result in
Lower - contralateral superior quadrantanopia Upper - contralateral inferior quadrantanopia
Neuroanatomical correlate of Balint’s syndrome
Bilateral lesions to dorsolateral parieto-occipital cortex, most often MCA-PCA infarcts
