Visual Lesion Localization

Question 1

how do images on the retina form?

Answer 1

inverted and reversed
info from the upper visual field is projected on the lower retina, R visual field is project on the L hemiretina

Question 2

where does the central fixation point fall?

Answer 2

on the fovea

Question 3

what creates the blind spot? where is it located?

Answer 3

optic disc
lateral to the macula

Question 4

what is the visual field?

Answer 4

total area seen by the combined visual field of both eyes

Question 5

how can the retina be divided?

Answer 5

by a vertical line, divides fovea and retina into two halves
nasal and temporal

Question 6

what is the monocular zone?

Answer 6

portion of the visual field that comes from only one eye, temporal crescent of the visual field projects to the nasal hemiretina

Question 7

what decussated in the optic chiasm?

Answer 7

visual information from the nasal hemiretinae

Question 8

what does each optic tract contain?

Answer 8

axons from the contralateral nasal hemiretina and ipsilateral temporal hemiretina

Question 9

stimuli from one visual hemifield are…

Answer 9

processed in the contralateral thalamus and cerebral cortex

Question 10

inferior optic radiations path

Answer 10

arc forward from thalamus into the temporal lobe near the inferior horn of the lateral ventricle to lingual gyrus
Meyer’s loop, info from the inferior retina

Question 11

upper optic radiations path

Answer 11

from thalamus, pass under parietal lobe to cuneus gyrus
info from the superior retina

Question 12

what are the two types of positive visual phenomena?

Answer 12

simple and formed

Question 13

what are examples of simple positive visual phenomena? what are some causes?

Answer 13

flashes, lights, colors, shapes
retinal detachment, glaucoma, migraines, occipital seizure

Question 14

what are examples of formed positive visual phenomena? what are some causes?

Answer 14

hallucinations of people/animals, complex scenes
focal seizures, complex migraines, neurodegenerative disorders, toxic disturbances, withdrawal

Question 15

what do formed positive visual phenomena arise from?

Answer 15

inferior occipitotemporal visual association cortex

Question 16

what is the release phenomenon?

Answer 16

formed visual hallucinations in an area of visual field loss

Question 17

what is a monocular scotoma? where is the lesion?

Answer 17

defined region of visual loss in a portion of one eye
retina

Question 18

what is monocular visual loss? where is the lesion?

Answer 18

loss of vision from one entire eye
optic nerve

Question 19

what is bitemporal hemianopia? where is the lesion?

Answer 19

loss of temporal visual fields bilaterally (loss of nasal retina info bilaterally)
optic chiasm

Question 20

what is contralateral homonymous hemianopia? where is the lesion?

Answer 20

injury to the same regions of the visual fields for both eyes
optic tract, lateral geniculate nucleus, entire optic radiation, or entire primary visual cortex unilaterally (DGH)

Question 21

what is contralateral superior quadrantanopia? where is the lesion?

Answer 21

“pie in the sky”
Meyer’s loop or lower bank of calcarine fissure (EJ)

Question 22

what is contralateral inferior quadrantanopia? where is the lesion?

Answer 22

“pie on the floor”
parietal lobe interrupting upper optic radiations or upper bank of calcarine fissure

Question 23

what can result in macular sparing?

Answer 23

partial lesions of the visual field because the fovea has a large representation throughout the pathway

Question 24

what can the MCA or PCA do in a lesion of the visual cortex?

Answer 24

provide collateral blood supply to the macular region of the visual cortex

Question 25

what is an altitudinal scotoma? where is the lesion?

Answer 25

upper or lower retina loss occlusion one of two major branches of the central retinal artery

Question 26

what can cause binocular altitudinal scotoma?

Answer 26

disease of the basilar artery

Question 27

where do a minority of fibers in the optic tracts go?

Answer 27

bypass lateral geniculate nucleus to go to the bronchium of the superior colliculus

Question 28

what are projections to the pretectal area* and superior colliculus important for?

Answer 28

directing visual attention and eye movements toward visual stimuli pupillary light reflex*

Question 29

where does the pretectal area and superior colliculus project to?

Answer 29

association cortex via relays in the pulvinar and lateral posterior nucleus of thalamus

Question 30

the pupillary light reflex is under what type of control

Answer 30

parasympathetic

Question 31

pupillary light reflex pathway

Answer 31

light activates retinal ganglion cells, project to both optic tracts to brachium of superior colliculus, synapse in pretectal area axons project bilaterally to Edinger-Westphal nucleus synapse on preganglionic parasympathetic neuron pregang fibers travel bilaterally in CN III to synapse on postgang para neurons in the ciliary ganglion postgang fibers to pupillary constrictor muscles

Question 32

direct vs consensual response

Answer 32

direct - same eye with light shone in it consensual - opposite eye

Question 33

pupil dilation is under what kind of control?

Answer 33

sympathetic

Question 34

pupil dilation pathway

Answer 34

Question 35

dorsal visual processing pathway

Answer 35

"where?" pathway to parieto-occipital association cortex motion and spatial relationships between objects and self

Question 36

ventral visual processing pathway

Answer 36

"what?" pathway to occipitotemporal association cortex analyzing form, with specific regions for colors, faces, letters

Question 37

cortical blindness

Answer 37

bilateral damage to primary visual cortex lack insight into disease (anosognosia) dismiss diagnosis, confabulate visions

Question 38

what can inferior occipitotemporal cortex damage cause?

Answer 38

prosopagnosia, achromatopsia, micropsia

Question 39

what is Balint's syndrome?

Answer 39

bilateral damage to dorsolateral parieto-occipital cortex simultanagnosia, optic ataxia, ocular apraxia

Question 40

prosopagnosia

Answer 40

inability to recognize faces, bilateral fusiform gyrus damage

Question 41

achromatopsia

Answer 41

central disorder of color perception; can't name, point to, or match colors presented visually can name/recall appropriate color of objects verbally

Question 42

micropsia

Answer 42

objects appear unusually small or large

Question 43

simultanagnosia

Answer 43

impaired ability to perceive parts of a visual scene as a whole; perceived area shifts unpredictably

Question 44

optic ataxia

Answer 44

impaired ability to reach for or point to objects under visual guidance; proprioception is intact though, can reach for an object once it has been touched

Question 45

ocular apraxia

Answer 45

difficulty voluntarily directing one's gaze toward objects in the periphery through saccades