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Neurosciences > Exam2Lec6Vision:CentralProcessing > Flashcards

Exam2Lec6Vision:CentralProcessing Flashcards

1
Q

What is most of the visual field

A

Binocular vision

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2
Q

What is the primary projections pathway?

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 receives input from only one eye (left or right) (has 6 layers)

A

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 temportal)

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 layes 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
  • What layers 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
has more procesessing space for macula

27
Q

Like the LGN, how is the striate cortex organized

A

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

28
Q

What layer does info enter the striate cortex?

A

4

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.

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
31
Q

Neurons in the striate cortex are tuned to what?

A

specific edge orientation

32
Q

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

A
  • Within a given column, neurons will respond preferentially to a specific shape orientation.
  • Across a row, neurons will respond to varying shape orientation.
  • In other words, individual ocular dominance columns are responsible for detecting a singular shape orientation. We combine information across columns to detect changes in orientation.
33
Q

mapping neurons for orientation preference in V1 primary visual cortex revels _ -type organization

A

pinwheel

34
Q

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

A

visual cortex (striate)

35
Q

what are the extrastriate visual cortical areas?

A

V2, V3, V4 and V5 and MT (middle temporal)

36
Q

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

A
  • WHERE (Dorsal) Pathway
  • WHAT (Ventral) Pathway
37
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
38
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)
39
Q

What is an anopsia or anopia?

A

defect in the visual field

40
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
41
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)
42
Q

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

A

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

43
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 (because only one eye) (contralateral) hemianopsia

44
Q

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

A

CENTRAL Optic Chiasm -> Bilateral loss of superior + inferior temporal vision
* Bitemporal hemianopsia
* Heteronymous because two different fields of the eyes were lost

45
Q

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

A

RIGHT Optic Tract ->Loss of LEFT visual field
* Homonymous (same visual field from both eyes) hemianopsia

46
Q

What happens when we have damage to the 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

47
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

48
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

49
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.

50
Q

Infarctions can lead to what?

A

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

51
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
52
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
53
Q

What is agnosias?

A

inability to identify something by sight

WHAT pathway

54
Q

What is simultanagnosis

A

inability to perceive more than one object at a time

55
Q

What is prosopagnosia

A

Inability to perceive faces (including your own)

Affects ventral pathway

56
Q

What is akinetopsia?

A

motion blindness

57
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)
58
Q

What is alexia and what is usually paired with?

A
  • inability to recognize words/read
  • agraphia-> cannot write
59
Q

What does congenital cataracts lead to?

A

leading to clouding of the lens

60
Q

What does cataracts inhibit?

A

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

61
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

62
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
63
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

64
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

Neurosciences (28 decks)

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