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Flashcards in Visual system Deck (51):
1

Lesions of the optic chiasm result in

Bitemporal hemianopia

2

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

3

Palinopsia

Persistence or reappearance of a recently viewed object; assoc. w/ parietal & occipital lobe lesions

3

Akinetopsia

Acquired cerebral motion blindness

4

A lesion of the optic nerve results in

Monocular visual loss or monocular scotomas

5

Clinical triad of Balint's syndrome

Simultanagnosia, optic ataxia, ocular apraxia

6

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

7

Formed visual hallucinations arise from

Inferior temporo-occipital visual association cortex

8

How is the pretectum involved in vision?

Changes in pupil size in response to light

9

Meyer's loop

Inferior optic radiations that arc forward into the temporal lobe; carry info from the inferior retina or superior visual field

9

Cortical blindness

Caused by bilateral lesions to the primary visual cortex

10

Common causes of optic chiasm lesions

Pituitary adenoma, meningioma, craniopharyngioma, hypothalamic glioma

11

Lesions of the LGN result in

Contralateral homonymous hemianopsia

11

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

13

Macula

Oval region that surrounds the fovea

14

Info from the fovea is represented by what portion of fibers in the topic nerve?

~1/2

14

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

15

Face/object recognition is localized to the

Midportion of the fusiform gyrus

16

The retina is supplied by what artery?

Ophthalmic

17

Anton's syndrome

Syndrome in which patients with cortical blindness deny blindness & confabulate visual images

17

Dorsal visual stream

"where", info regarding spatial analysis & orientation; runs along top side of cerebrum from occipital to parietal visual areas

17

An inability to recognize facial emotion is associated with lesions to the

Bilateral amygdala

18

Lesions of the lower/upper optic radiations result in

Lower - contralateral superior quadrantanopia Upper - contralateral inferior quadrantanopia

18

Neuroanatomical correlate of Balint's syndrome

Bilateral lesions to dorsolateral parieto-occipital cortex, most often MCA-PCA infarcts

19

The "what" visual stream is supplied by what artery?

PCA

21

Fortification scotoma

Visual blurring & scotomas with scintillating appearance or that consist of jagged alternating light & dark zigzag lines; seen in migraine

22

Off-center receptors

Inhibited by light in the center of the receptive field & excited by light in the surrounding area

23

Release phenomenon

Pts with visual deprivation in part or all of their visual fields caused by either ocular or CNS lesions may see objects, people, or animals in the region of visual loss

24

STS stream

"specialized movement"; visual analysis of mvmt of body parts & biological objects; located in the superior temporal sulcus

26

Amaurosis fugax

TIA of the retina

27

Ventral visual stream

"what", info regarding shape, pattern; runs along underside of cerebrum from occipital to temporal visual areas

29

Charles Bonnet syndrome

Visual hallucinations following loss of vision due to cataracts, glaucoma, or age-related macular degeneration; may be simple or complex

30

Optic disc

Region where axons leaving the retina gather to form the topic nerve

31

The "where" visual stream is supplied by what artery?

MCA-PCA watershed area

33

P cells

Have small receptive fields, sensitive to fine visual detail & colors, project to parvocellular layers of LGN

35

Lesions of the upper/lower banks of the calcarine fissure result in

Upper - CL inferior quadrantanopia Lower - CL superior quadrantanopia

36

On-center receptors

Excited by light in the center of the receptive field, inhibited by light in surrounding area

37

Lesions of the entire calcarine fissure result in

CL homonymous hemianopia

38

Bilateral lesions of the middle temporal gyrus result in

Akinetopsia - can't perceive visual motion

39

What percentage of retinal input is relayed to the striate cortex via the LGN?

70%

41

Tectopulvinar pathway

Optic tract => superior colliculus => pulvinar => other visual cortical areas

42

Lesions to the dorsal visual association pathway will result in

Visuospatial disorientation syndromes (visual neglect, dressing apraxia, simultanagnosia, Balint's)

43

Geniculostriate pathway

Optic tract => LGN => striate cortex

44

M cells

Have large receptive fields, respond best to gross stimulus features & mvmt, project to magnoscellular layers of LGN

45

Center-surround

Concentric receptive fields

46

Lingula

Area below the calcarine fissure

47

Hering's opponent process theory of color vision

3 pairs of receptors: red/green, yellow/blue, white/black; excitation of one inhibits the other

48

Young-Helmholz trichromatic theory of color vision

Red, blue, green receptors in the retina

49

Cuneus

Area above the calcarine fissure

50

What type of visual phenomena may be seen in occipital seizures?

Pulsating color lights or moving geometric shapes

51

A man with a history of glaucoma complains of well-formed visual hallucinations.  What is the name of this syndrome?

Charles Bonnet Syndrome