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OP2204- Optometric Neurophysiology Lectures > 2. Topography 1 > Flashcards

2. Topography 1 Flashcards

1
Q

Why is an organization important in the visual pathway?

A

To maintain maps of the visual world. Such that the image formed on the retina is maintained in a parallel manner.

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2
Q

In the sensory/ motor cortex unequal distribution is seen - some aspects cover a larger area in the cortex why?

A

Distribution relates to the number of receptors (Sensory or motor) found in that are, some areas require more space due to this.

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3
Q

Reason for over representation of the fovea in the cortex?

A

A lot of ganglion cells are carrying info to the cortex in comparison to the peripheral retina.
THIS IS KNOWN AS THE MAGNIFICATION FACTOR.

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4
Q

Describe the organization of cells that are together in point in space, in relation to the cortex and RGCs.

A

2 points together in space = next to each other in the retina & fibers from those ganglion cells stay together.

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5
Q

What is monocular correspondence?

A

In 1 eye the adjacent information remains adjacent as you move to the visual maps.

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6
Q

2 types of point-to-point correspondence?

A

Monocular & Binocular

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7
Q

Binocularity in LGN?

A

No binocularity in LGN

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8
Q

Describe the overlap seen when eyes look straight ahead vs when eyes converge?

A

Straight ahead: Visual fields overlap
Eyes converge: Bigger overlap of visual fields

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9
Q

Describe the overlap seen when eyes look straight ahead vs when eyes converge?

A

Straight ahead: Visual fields overlap
Eyes converge: Bigger overlap of visual fields

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10
Q

Are eyes the only determining factor of visual fields?

A

No- head and body movements also contribute to movement of field view.

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11
Q

How does info from photoreceptors, horizontal, amacrine and bipolar cells move to optic nerve ?

A

Info from all this 4 cells moves to retinal ganglion cell layer, that gives rise to a single axon that moves to the optic disc, this will exit through optic nerve head and move to chiasma.

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12
Q

very few fibers in the fovea, why?

A

Because very little overlying tissue in the fovea

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13
Q

RGCs in the fovea location?

A

Found at the periphery, because it has been pushed aside

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14
Q

Horizontal Raphe denotes?

A

Horizontal meridian of the eye

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15
Q

Describe the fibers that are above and below the raphe?

A

The fibers arcuate as they move to the optic disc

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16
Q

Is raphe observed at the optic disc, if yes- explain?

A

Yes
All fibers that emerge below the raphe move to the lower portion of the disc

17
Q

A distinction/ separation is observed of fibres coming from the temporal vs nasal retina- TRUE OR FALSE?

A

TRUE

18
Q

What is arcuate fiber trajectory?

A

Virtually no crossing between upper and lower at the level of Raphe.

19
Q

Raphe more distinct for nasal or temporal region?

A

More distinct for nasal region

20
Q

What is extra striated cortex?

A

Areas beyond V1

21
Q

Nasal fields crossing leads to?

A

Representation of hemi-fields

22
Q

Why is rotation of retinal coordinate maps important?

A

To allow it to get plugged into LGN.

23
Q

Describe what happens to nasal fibers- Inferior peripheral and superior peripheral at the chiasma and why?

A

Inferior peripheral: Anterior knee of Willbrand
Superior peripheral: Posterior knee of Willbrand
WHY- Fibers are trying to keep a map a cross the chiasma

24
Q

Macular crossing occurs at what end of the chiasma?

A

Posterior end

25
Q

Eye is distal to the brain- meaning?

A

Eye is near to the brain

26
Q

In the distal optic nerve- Macular fibers take up central position, why?

A

A lot more fibers are emmerging from the macular compared to the periphery

27
Q

Direction of rotation of retinal coordinates at the chiasma?
Implication of this?

A

Nasal
Implication: Puts upper retina medially & lower retina put laterally

28
Q

Once map emerges from optic tract UT/UN replaced by?

A

Superior

29
Q

Nasal and Temporal fibers go to which layers:

A

Nasal: 1,4 & 6
Temporal: 2,3 & 5

30
Q

In the cortex, Raphe corresponds to?

A

Sulcus

31
Q

How many individual maps within the LGN?

A

12

32
Q

What part of the maps do not overlap with each other?

A

Monocular crescents do not overlap

OP2204- Optometric Neurophysiology Lectures (8 decks)

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