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Perception Exam 3 > Perception in cortex > Flashcards

Perception in cortex Flashcards

1
Q

How many cells in retina?

A

126 mil

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2
Q

How many cells in Cortex?

A

250 mil

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3
Q

How many layers in V1?

A

6

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4
Q

How many layers in Cortex?

A

6

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5
Q

How many cells in V1?

A

150 mil

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6
Q

Tell me about stellate cells

A

Intracortical

Connect LGN and pyramidal

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7
Q

Tell me about pyramidal cells

A

Very long
Apex Out
Connect extrastriate to LGN

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8
Q

Tell me about layer 1 of V1

A

1,2,3 go to extra striate
4,5,6 go back to LGN
Strongly influences deeper pyramidal cells
Role in visual attention and neglect
Thick and thin stripes

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9
Q

What is the V1 layer 1 made up of?

A

Synapses of Extra striate and pyramidal and

LGN and pulvinar

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10
Q

What’s up with V1 layers 1 and 2?

A

Where projections start (Full neurons here, only synpases in V1)
Also role in binocularity and figure-ground
Magno to V5
Parvo to V4

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11
Q

Purpose of Layer 4 and what’s it broken into?

A

Input layer - info to extrastriate or retinal tectal
Broken up into
4a
4b: Goes to V5/MT and superior colliculus
4c(a)
4c(b)

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12
Q

V1 layers 5 and 6 do what again?

A

Loop back to retinotectal/retino geniculate (LGN+Pulvinar)
Layer 6 is the neural loop and takes info from LGN back.
Deeper layers will send info from cortex to LGN
Obvi helps with saccades

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13
Q

What the eff are Meynert cells?

A

Cells of V1 layers 5 and 6 that go from V5/MT to superior colliculus

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14
Q

Where’s the Line of Gennari

A 
Demarcation in V4 where input from the LGN to the cortex goes
4a: From Parvo
4b: From V5/MT
4c(a): From Magno
4c(b): From Parvo
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15
Q

Which layers of V1 go to extrastriate? Where do they go?

A

1,2,3

V2, V3, V4, V5

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16
Q

Which layers of V1 go back to LGN?

A

4: input

5 & 6 go back to LGN

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17
Q

How much of the cortex is central vision?

A

2/3

18
Q

What’s cortical magnification

A

Cortex cares more about foveal vision. Magnified in importance while periphery fades

19
Q

How is the visual cortex arranged?

A

Layers 1-6

Then columnar packs of gum alternating between eyes

20
Q

Where are the cortical blobs?

A

Going down columns of V1. See color so only seen by Parvo stream.

21
Q

What dye is used to visualize cortical blobs and how does it work?

A

Cytochrome oxidase stain

Dies areas that use lots of ATP

22
Q

What types of fields to cortical blobs have?

A

Same as photoreceptor fields upstream. Red/green fields

23
Q

What are the 3 cortical cells Hubel and Wiesel found and which one doesn’t exist

A

Simple
Complex
Hypercomplex doesn’t exist

24
Q

What do simple cells do

A

Fire APs when visual stimulus in certain orientation

25
Q

Where do signals to simple cells come from?

A

Summate signals from LGN to a simple cell

26
Q

What types are there?

A

On and off as well as simple edge detectors

27
Q

What do complex cells do?

A

Only fire APs when orientation and movement of stimulus is correct
If goes opposite direction, will flatline

28
Q

Whatre endstops?

A

Limits to how long a stimulus can be before signals start to weaken. Found in simple and complex cells
Previously mistaken for hypercomplex cells

29
Q

How much space does binocularity take up in the visual cortex?

A

2/3

30
Q

Where does binocularity first occur?

A

Visual cortex

31
Q

What’re the types of stereo cortical cells?

A

Course stereo and fine stereo cells

32
Q

What’re the course cells?

A

Car driving cells
Also lets you do magic eye
2 types of course cells
Far course: beyond line of site. Inhibited if within line of fixation
Near course cells: Excitation and inhibition reverse far

33
Q

What’s responsible for the magic eye effect?

A

Course cells

34
Q

What percentage of stereo cells does course cells make up?

A

30%

35
Q

What do fine stereo cells do?

A

Needle threading stereopsis

36
Q

What’s the difference between fine tuned excitatory and fine tuned inhibitory stereopsis cells?

A

Excitatory: Excited with specific disparities up to 1 degree
Inhibitory: inhibited with stereo disparity

37
Q

What percentage of stereo cells is tuned excitatory?

A

50%

38
Q

What percentage of stereo cells is tuned inhibitory

A

20%

39
Q

What happens with short term abuse of visual system?

A

Complex cells tire out and get motion receptors to habituate. Get water fall illusion (V5/MT)

40
Q

What happens with long term abuse of the visual system?

A

Amblyopia! Can be meridional

If certain oriented edge detectors aren’t stimulated, will also switch directions

Perception Exam 3 (5 decks)

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