Unit 2: Visual System Flashcards

1
Q

What is the structure that makes up the visual center?

A

Macula lutea

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2
Q

What receptors is the macula lutea comprised of?

A

Cones because it’s the area of high visual acuity

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3
Q

What is the structures that is a depression in the center of the macula lutea?

A

Fovea centralis

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4
Q

The fovea centralis is made of what?

A

Foveola (cones only)

Because this is where visual acuity of foveola that is the highest

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5
Q

What is the peripheral border of the functional retina called?

A

Ora serrata

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6
Q

There is an area of convergence of fibers of ganglion cells that form the optic nerve. What is this area called?

A

Optic papilla or the optic disc

This is medial (nasal) and superior to the macula

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7
Q

What is the retinal “blind spot” that has no rods or cones?

A

The optic papilla or optic disc.

This is where the fibers of ganglion cells converge to form the optic nerve. That’s why there are no rods or cones.

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8
Q

What is the name of the neurons of the retina?

A

Bipolar cells

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9
Q

The convergence of many rods to one bipolar cell results in:

A

Summation

The rod system provides for vision of low resolution/acuity and also provides for vision in low light conditions.

10 rods/bipolar cell near macula lutea
100 rods/bipolar cell near ora serrata

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10
Q

Neurons that innervate bipolar cells are called:

A

Ganglion cells

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11
Q

What part of the retina is best suited for low resolution vision, low light vision?

A

Peripheral retina

Because it mostly contains rods

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12
Q

What part of the retina is best suited for color vision, high resolution vision?

A

Macular retina

Because it is comprised mostly of cones and very little or no convergence of bipolar cells on rods.

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13
Q

What do axons of ganglion cells of the retina form?

A

Optic nerves

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14
Q

Fibers from nasal halves of each retina decussate here (temporal fibers, which do not decussate)

A

Optic chiasm

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15
Q

Fibers within this structure carry visual data from contralateral visual field:

A

Optic tracts

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16
Q

The right optic tract carries visual data from the ___ visual field

A

Left

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17
Q

Fibers within the right optic tract are from ganglion cells located in the:

A

Right (nasal) half of the left retina

Right (temporal) half of the right retina

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18
Q

Optic tracts project into the:

A

Lateral geniculate body/nucleus (LGB/LGB) of the thalamus

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19
Q

What nucleus relays neurons for visual data?

A

LGB/LGN (thalamus)

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20
Q

What is the pathway of vision to the cortex from the optic tracts?

A

LGB neurons send axons to posterior limb of internal capsule and then to the cerebral cortex on the medial aspect of the occipital lobe

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21
Q

Meyer’s loop relays visual information from the ________ of the visual field

A

Contralateral upper quandrant

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22
Q

What initiates the processing of visual data?

A

Primary visual cortex (V1)

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23
Q

where is the primary visual cortex (V1) located?

A

Upper and lower banks of calcarine sulcus (occipital lobe)

Corresponds with Brodmann map area 17

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24
Q

Primary Visual Cortex maintains retinotopic organization. Where is the macular visual field located in the Primary Visual Cortex (v1)?

A

Posterior 1/3 of visual cortex

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25
Q

Primary Visual Cortex maintains retinotopic organization. Where is the peripheral visual field located in the Primary Visual Cortex (v1)?

A

Anterior 2/3 of visual cortex

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26
Q

Primary Visual Cortex maintains retinotopic organization. Where is the contralateral lower quadrant of the Primary Visual Cortex (v1)?

A

Upper banks fo calcarine sulcus

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27
Q

Primary Visual Cortex maintains retinotopic organization. Where is the contralateral upper quadrant in the Primary Visual Cortex (v1)?

A

Lower banks of calcarine sulcus

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28
Q

What is the thing that functions to allow for conscious awareness of visual stimuli?

A

Primary Visual Cortex (v1)

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29
Q

What would a lesion of the cortex adjacent to calcarine sulcus (v1)?

A

Cortical blindness

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30
Q

What would a unilateral lesion to the Calcarine Sulcus (v1) do? (One side of cortex is damaged)

A

Loss of vision in the contralateral half of the visual field in both eyes

31
Q

Where is the visual association cortex located?

A

Medial/lateral portion of occipital lobe

(Also the inferolateral temporal and som areas of posterior parietal)

Corresponds with Brodmann map areas 18, 19

32
Q

Which gyri process the visual association cortex?

A

Cuneate Gyrus and Lingual Gyrus

33
Q

What receives input from 1˚ visual cortex & other brain regions and integrates current visual data with previous experiences with visual data? Ie recognize objects, faces, shapes, colors and appreciate motions, relations, and computations mediated in movement

A

Visual Association Cortex

34
Q

If the primary visual association cortex is intact, a lesion of the visual association cortex may result in:

A

Visual agnosia or facial agnosia

No blindness

35
Q

Visual agnosia

A

Inability to appreciate significant of visual information

36
Q

Facial agnosia

A

Inability to identify familiar faces

May have difficulty distinguishing biological sex, age, emotional state

37
Q

What coordinates activities controlled by the hypothalamus that are dependent on circadian rhythms?

A

Suprachiasmatic nucleus

38
Q

Where is the retinohypothalamic tract going?

A

Ganglia from retina go to suprachiasmatic nucleus in the hypothalamus

39
Q

What fibers influence pupillary light reflex/respons?

A

Retinotectal fibers

40
Q

What influences avoidance reflex (involuntary/reflexive movement in response to object in visual field traveling at high velocity)?

A

Retinotectal fibers

41
Q

Where are retinotectal fibers going?

A
  1. Start from optic tract.
  2. Travels through superior brachium.
  3. Synapses on superior colliculus.
  4. To the tectum
42
Q

What fibers coordinate visually-dependent involuntary reflexes of the eyes such as tracking a moving object across the visual field?

A

Corticotectal fibers

43
Q

Tell me the tract of cortico-tectal fibers

A
Start at the occipital cortex
Travels in the geniculocalcarine tract
Traverses the superior brachium
(Does NOT go through thalamus)
Synapses in superior colliculus (tectum)
44
Q

Anopsia (anoxia)

A

Loss of vision

45
Q

Hemianopsia (hemianopia)

A

Loss of vision in the 1/2 of the visual field

46
Q

Quadrantanopsia (quadrantanopia)

A

Loss of vision in 1/4 of the visual field

47
Q

Homonymous

A

Same

48
Q

Example: right homonymous hemianopsia

A

Same deficit in both eyes and the deficit is in the right half of visual field

49
Q

Lesion of R optic nerve

Which eye (R/L/Both) and what part of visual field is affected?

A

Right Eye

Visualization on page 29

50
Q

Lesion of R optic nerve

What is our deficit?

A

Entire visual field for right eye = right eye blindness = right eye anopia

Pg 29

51
Q

Lesion of the optic chiasm at midline

Which eye (R/L/Both) and what part of visual field is affected?

A

Left half of visual field for left eye
Right half of visual field for right eye

Pg 30

52
Q

Lesion of optic chiasm at midline (pituitary tumor)

What is our deficit?

A

Bilateral hemianopsia

Pg 30

53
Q

Lesion: compression of right lateral margin of optic chiasm (aneurysm of internal carotid artery)

Which eye (R/L/Both) and what part of visual field is affected?

A

Right eye, left/nasal/medial visual field

Pg 32

54
Q

Lesion: compression of right lateral margin of optic chiasm

What is the deficit?

A

Nasal hemianopsia of the right eye

Pg 32

55
Q

Lesion of the right optic tract OR right optic radiations OR right 1˚ visual cortex

Which eye (R/L/Both) and what part of visual field is affected?

A

Both eyes and left visual field

Pg 33

56
Q

Lesion of the right optic tract OR right optic radiations OR right 1˚ visual cortex

What is the deficit?

A

Left homononymous hemianopsia

Pg 33

57
Q

Lesion of right Meyer’s loop (possible temporal lobe tumor)

Which eye (R/L/Both) and what part of visual field is affected?

A

Both eyes. Left half of the visual field, and the superior quarter of that field.

Pg 33

58
Q

Lesion of right Meyer’s loop (possible temporal lobe tumor)

What is the deficit?

A

Left superior homonymous quadrantanopia

Pg 33

59
Q

ratio of ganglion cells

to bipolar cells in fovea

A

1:1

60
Q

Ratio of cones to bipolar cells in the fovea

A

1:1

61
Q

rods to bipolar cell ratio

near the macula lutea

A

10:1

62
Q

rods to bipolar cell ratio

near the ora serrata

A

100:1

63
Q

Lesion of the visual association cortex could result in:

A

Facial agnosia

64
Q

Where are fibers from the retinotectal fibers going?

A

From the retina to the tectum via superior brachial (“arm” of superior colliculus)

64
Q

The image of an object projected onto the retina will be___________ and _____________.

A

Inverted and reversed

64
Q

area seen by both eyes = ___________

A

Total visual field

65
Q

an image from the upper left quadrant of the visual field will project onto what part of the retina in each eye?

A

left retina - the lower right (nasal) quadrant

Right retina - the lower right (temporal) quadrant

66
Q

How is visual data organized throughout the central pathway?

A

Retinotopic

Example: visual data from the right halves of both retina (left visual field data) will project to the right side of the brain

67
Q

LGB axons form optic radiations that called ________.

A

geniculocalcarine tract

68
Q

The geniculocalcarine tract passes around the_________ and _________ of the lateral ventricle.

A

collateral trigone, inferior horn

69
Q

fibers of the geniculocalcarine tract that loop around the inferior horn of the lateral
ventricle (temporal lobe) and synapse on lower banks of calcarine sulcus comprises ___________.

A

Meyer’s loop

70
Q

Most of the functional area of the primary visual cortex is located where within the calcarine sulcus?

A

deep within sulcus, minimal amount on medial surface

71
Q

Where is the photosensitive chemical rhodopsin found and how does it work?

A

It is found in the rod cells of the neural layer of the retina. Light changes the configuration of rhodopsin which results in a change in the membrane potential of the rod cell to allow for transduction of light information into visual data

72
Q

There are three types of cone receptors which include one of three photosensitive pigments that absorb either ______, ______ or _______ light.

A

Red, green, blue