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Neuroscience Exam 2 > Lecture 6:Vision-Central Processing > Flashcards

Lecture 6:Vision-Central Processing Flashcards

1
Q

Most of the visual field is what type of vision?

A

Binocular vision

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2
Q

What is the primary projections pathway? (7)

A
  1. Retina
  2. Optic Nerve
  3. Optic Chiasm
  4. Optic Tract
  5. Lateral Geniculate Nucleus
  6. Optic Radiations
  7. Striate (Primary Visual) Cortex
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3
Q

Optic nerve axons from the nasal retina cross at the _ _ and joins axons from the _ _ of the other eye

A

Optic nerve axons from the nasal retina cross at the optic chiasm and joins axons from the temporal retina of the other eye

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4
Q

What makes up the optic tract?

A

the contralateral and ipsilateral axons together

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5
Q

What reveives input from only one eye (has 6 layers)

A

Lateral Geniculate Nucleus (LGN)

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6
Q

What makes up the optic radiations? Where are the optic rad. projected?

A
  • Axons from the LGN
  • striated cortex(V1)
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7
Q

Which optic nerve axons cross at optic chiasm? (nasal or temporal)

A

NASAL, temporal stays ipsilateral

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8
Q

What is the hypothalamus for?

A
  • regulation of circadian rhythms (wake/sleep cycle)

light info

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9
Q

What is the pretectum for?

A

reflex control of pupil and lens

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10
Q

What is superior colliculus for?

A
  • orienting the movement of head and eyes
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11
Q

how is the lateral geniculate nucelus organized?

A

left and right LGN are organized into six distinct layers

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12
Q

LGN-> mono or binocular?

A

monocular! there is no intergration for depth or mvt at the thalmas

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13
Q

The LGN layers recieves what?

A

retinal ganglion cell inputs from either the left or right eye but NOT BOTH

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14
Q

What is not there in the LGN

A

binocular processing

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15
Q

What is preserved in the LGN

A

retinal receptive fields

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16
Q

What are the three retinal ganglion cells that project to LGN locations

A
  • Parvo-cellular (P) ganglion cells
  • Magno-cellular (M) ganglion cells
  • Koniocellular (K) ganglion cells
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17
Q
  • Where do P ganglion cells project?
  • What are their characterics?
  • What do they carry and respond to?
A
  • project into layers 3-6
  • Small cell body/dendritic morphology
  • DO carry color information
  • Respond to sustained (not moving) stimuli
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18
Q

Where do M ganglion cells project into?
What are their characteristics?
What do they not carry?
What do they respond to?

A
  • layers 1 and 2
  • Large cell body/dendritic morphology
  • DO NOT carry color information
  • Respond to transient (moving) visual stimuli+low light

more rods than cones

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19
Q

Where do K ganglion cells project into?
What is their charactertics?
What is their role?

A
  • inbetween layers
  • very small soma
  • fxn is poorly understood-> some role in color perception
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20
Q

projections onto the retina are _ _ and _.

A

upside down and backwards

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21
Q

Parietal (Superior) Optic Radiations carry information from:

A

Superior retinal quadrants
Inferior visual field

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22
Q

Temporal (Inferior) Optic Radiations carry information from:

A

Inferior retinal quadrants
Superior visual field

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23
Q

Where is the meyer’s loop?

A

Temporal (inferior) optic radiations

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24
Q

How is the striated cortex organized?

A

binocular/monocular vision (macula) and superior/inferior visual fields

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25
Q

What is the magnification factor?

A

A large cortical V1 region is devoted to processing information from the small retinal foveal (macula) region.

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26
Q

Is inferior or superior visual fields bigger in the striate cortex

A

superior

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27
Q

Like the LGN, how is the striate cortex organized

A

organized into layers which receive input from either left or right eye

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28
Q

What layer does info enter the striate cortex?

A

4

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29
Q

What processing do we have after layer 4?

A

After layer 4 (layers 3, 2, and 1), we then begin binocular visual processing.

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30
Q

How are the layers in the striate cortex dived further? what are they responsible for?

A
  • Layers are further divided into ocular dominance columns
  • Responsible for processing orientation of shapes
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31
Q

Neurons in the striate cortex are tuned to what?

A

specific edge orientation

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32
Q

Within the ocular dominance column, neurons will respond to what?

A
  • Within a given column, neurons will respond preferentially to a specific shape orientation.
33
Q

Within the ocular dominance row, neurons will respond to what?

A
  • Across a row, neurons will respond to varying shape orientation.
34
Q

Individual ocular dominance columns are responsible for?

A

Detecting a singular shape orientation

35
Q

How are detect changes in orientation?

A

Combine information across columns

36
Q

Mapping neurons for orientation preference in V1 primary visual cortex reveals _ -type organization

A

pinwheel

37
Q

When are we consciously aware of our visual field (conscious perception)

A

visual cortex (striate)

38
Q

What are the extra-striate visual cortical areas? (5)

A
  • V2
  • V3
  • V4
  • V5
  • MT (middle temporal)
39
Q

What are the two pathways off the striate cortex (v1)

A
  • WHERE (Dorsal) Pathway
  • WHAT (Ventral) Pathway
40
Q

What is the path for the WHERE (dorsal) pathway and the WHAT (ventral) pathway?

A
  • WHERE: V1 -> V2 -> MT ->Parietal Lobe
  • WHAT: V1->V2->V4-> Temporal Lobe
41
Q

What is the WHERE and WHAT pathway responsible for?

A
  • WHERE: Responsible for spatial recognition (i.e. motion, objects relative to each other in space)
  • WHAT: Responsible for object recognition (i.e. faces)
42
Q

What is an anopsia or anopia?

A

defect in the visual field

43
Q

What words do we use to see how much of the visual world is affected?

A
  • Hemi – half of the visual world
  • Quadrant – one quarter of the visual world
44
Q

What words do we use for which part of the visual world is affected?

A
  • Homonymous – on the same side of the visual world (congruent)
  • Heteronymous – on different sides of the visual world (incongruous)
45
Q

What happens when we have damage to the optic nerve ? (ex: right optic n.)

HIGH yield

A

RIGHT Optic Nerve ->Complete loss of information from right eye

  • Unilateral Blindness
46
Q

What damage causes Unilateral Blindness?

A

Damage in the Optic nerve

47
Q

What happens when we have damage to lateral optic chiasm (what is the offical name)

A

LATERAL Optic Chiasm -> Unilateral (right) loss of superior + inferior temporal vision

  • Incomplete (contralateral) hemianopsia
48
Q

What damage causes Incomplete (contralateral) hemianopsia?

A

Lateral optic chiasm

49
Q

What happens when we have damage to central optic chiasm (+ offical name)

HIGH yield

A

CENTRAL Optic Chiasm -> Bilateral loss of superior + inferior temporal vision

  • Bitemporal hemianopsia
  • Heteronymous because two different fields of the eyes were lost
50
Q

What damage causes Bitemporal hemianopsia?

A

Central optic chiasm

51
Q

What happens when we have damage in the (Right) optic tract? (+offical name)

HIGH yield

A

RIGHT Optic Tract ->Loss of LEFT visual field

  • Homonymous hemianopsia
    (same visual field from both eyes)
52
Q

What damage causes Homonymous hemianopsia?

A

Optic Tract

53
Q

What happens when we have damage to the (right) temporal (inferior/meyers loop) optic radiation? (+offical name)

A

RIGHT Temporal (Inferior/Meyers Loop) Optic Radiation -> Loss of LEFT SUPERIOR visual field
* Homonymous superior quadrantanopsia

54
Q

What damge causes Homonymous superior quadrantanopsia?

A

Temporal (inferior/Meyer’s Loop) Optic Radiation

55
Q

What happens when the RIGHT Parietal (Superior) Optic Radiation gets damage (+offical name)

A

RIGHT Parietal (Superior) Optic Radiation -> Loss of LEFT INFERIOR visual field
* Homonymous inferior quadrantanopsia

56
Q

What damage is cause Homonymous inferior quadrantanopsia?

A

Parietal (Superior) Optic Radiation

57
Q

What happens when we have complete parito-occipital interruption of the optic radiation (+offical name)

A

Loss of superior + inferior LEFT visual field w/ macular sparing
* Homonymous hemianopsia (often result in macula sparing)

58
Q

What would happen if we have incomplete damage to the visual cortex?

A

homonymous (both eyes) scotomas, usually encroaching at least acutely on central vision.

59
Q

Infarctions can lead to what?

A

defects in the visual pathway depending on which structure the vessel is supplying

60
Q

What are the main blood supplies we need to know and what do they supply

A
  • Ophthalmic Artery ->Optic Nerve
  • Middle Cerebral Artery ->Optic Tract
  • Deep Branch of the Middle Cerebral Artery ->Optic Radiations
  • Posterior Cerebral Artery -> V1 Striate Cortex
61
Q

The middle cerebral artery is more likely to cause damage where? What about the posterior cerebral artery?

A
  • middle: More likely to cause damage to peripheral visual field
  • posterior: More likely to cause damage to central visual field
62
Q

What is agnosias?

HIGH yield

A

inability to identify something by sight

WHAT pathway

63
Q

What is simultanagnosis?

HIGH yield

A

inability to perceive more than one object at a time

64
Q

What is prosopagnosia?

HIGH yield

A

Inability to perceive faces (including your own)

Affects ventral pathway

65
Q

What is akinetopsia?

HIGH yield

A

motion blindness

66
Q

What are these?

  • Apperceptive agnosia –
  • Associative agnosia -
  • Semantic agnosia –
  • Achromatopsia –
A
  • Apperceptive agnosia – Inability to distinguish shapes
  • Associative agnosia – inability to recognize what something is used for
  • Semantic agnosia – inability to recognize signs and their symbolic meanings
  • Achromatopsia – loss in color vision (V4 and V8)
67
Q

What is alexia and what is usually paired with?

A
  • inability to recognize words/read
  • agraphia-> cannot write
68
Q

What does congenital cataracts lead to?

A

leading to clouding of the lens

69
Q

What does cataracts inhibit?

A

inhibits the ability of the lens to properly refract light onto the retina

70
Q

With cataracts, the visual pathway is not damage, so what is the problem?

A

The visual pathway is not damaged. Instead, the intensity of the stimulus is affected causing decreases in contrast and brightness sensitivity

  • Can also lose macula vision
71
Q
  • When do we have lots of plasticity in vision?
  • What did they find out when looking fixing catarats in young children and teens?
A
  • Younger, up to eight
  • some of them did realy well but others not so much
  • the older children did not change as much as younger children but their visual cortex was able to adapt closer to normal level
72
Q

When you have a younger child that has a detect in one eye and wanting to fix it, what is VERY IMP? WHY?

A

You need to cover the unaffected eye because the eyes are competitive

  • once one eye is damage, the other eye will take over that visual cortex
73
Q

What is up with peripheral drift optical illusions?

A
  • characterized by anomalous motion that can be observed in the peripheral vision
  • d/t edge and motion sensitivity of receptor fields associated with eye mvt
74
Q
  1. All of the following are true regarding parvo-cellular (P) retinal ganglion cells EXCEPT:
    A. Found in layers 3 through 6 of the lateral geniculate nucleus
    B. Have relatively small cell body and dendritic morphology
    C. They do not carry color information
    D. Primarily respond to sustained stimuli
A

C. They do not carry color information

75
Q
  1. A 43-year-old man is rushed to the ED following the onset of strange neurological symptoms. MRI confirms the presence of an infarction in a region of the brain responsible for spatial recognition. Which of the following pathways is likely being affected?
    A. Ventral; V1→V2→MT→Parietal Lobe
    B. Dorsal; V1→V2→MT→Parietal Lobe
    C. Ventral; V1→V2→V4→Temporal Lobe
    D. Dorsal; V1→V2→V4→Temporal Lobe
A

B. Dorsal; V1→V2→MT→Parietal Lobe

76
Q
  1. Information from the inferior visual field projects onto the primary visual (striate) cortex via which of the following structures?
    A. Parietal Optic Radiations
    B. Superior Colliculus
    C. Temporal Optic Radiations
    D. Inferior Colliculus
A

A. Parietal Optic Radiations

77
Q
  1. A 23-year-old presents to her Ophthalmologist after a gradual decrease in perception from her left visual field. After further examination the physician suspects that the patient is experiencing homonymous hemianopsia due to a lesion along her visual pathway. If so, in which of the following structures is the lesion most likely located?
    A. Right Optic Nerve
    B. Left Visual Cortex
    C. Right Optic Tract
    D. Left Temporal Optic Radiation
A

C. Right Optic Tract

78
Q
  1. Which of the following blood vessels is primarily responsible for providing blood supply to the striate cortex?
    A. Ophthalmic Artery
    B. Middle Cerebral Artery
    C. Deep Branch of the Middle Cerebral Artery
    D. Posterior Cerebral Artery
A

D. Posterior Cerebral Artery

Neuroscience Exam 2 (9 decks)

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