Perception in cortex

Question 1

How many cells in retina?

Answer 1

126 mil

Question 2

How many cells in Cortex?

Answer 2

250 mil

Question 3

How many layers in V1?

Answer 3

6

Question 4

How many layers in Cortex?

Answer 4

6

Question 5

How many cells in V1?

Answer 5

150 mil

Question 6

Tell me about stellate cells

Answer 6

Intracortical

Connect LGN and pyramidal

Question 7

Tell me about pyramidal cells

Answer 7

Very long
Apex Out
Connect extrastriate to LGN

Question 8

Tell me about layer 1 of V1

Answer 8

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

Question 9

What is the V1 layer 1 made up of?

Answer 9

Synapses of Extra striate and pyramidal and

LGN and pulvinar

Question 10

What’s up with V1 layers 1 and 2?

Answer 10

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

Question 11

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

Answer 11

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

Question 12

V1 layers 5 and 6 do what again?

Answer 12

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

Question 13

What the eff are Meynert cells?

Answer 13

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

Question 14

Where’s the Line of Gennari

Answer 14

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

Question 15

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

Answer 15

1,2,3

V2, V3, V4, V5

Question 16

Which layers of V1 go back to LGN?

Answer 16

4: input

5 & 6 go back to LGN

Question 17

How much of the cortex is central vision?

Answer 17

2/3

Question 18

What’s cortical magnification

Answer 18

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

Question 19

How is the visual cortex arranged?

Answer 19

Layers 1-6

Then columnar packs of gum alternating between eyes

Question 20

Where are the cortical blobs?

Answer 20

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

Question 21

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

Answer 21

Cytochrome oxidase stain

Dies areas that use lots of ATP

Question 22

What types of fields to cortical blobs have?

Answer 22

Same as photoreceptor fields upstream. Red/green fields

Question 23

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

Answer 23

Simple
Complex
Hypercomplex doesn’t exist

Question 24

What do simple cells do

Answer 24

Fire APs when visual stimulus in certain orientation

Question 25

Where do signals to simple cells come from?

Answer 25

Summate signals from LGN to a simple cell

Question 26

What types are there?

Answer 26

On and off as well as simple edge detectors

Question 27

What do complex cells do?

Answer 27

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

Question 28

Whatre endstops?

Answer 28

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

Question 29

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

Answer 29

2/3

Question 30

Where does binocularity first occur?

Answer 30

Visual cortex

Question 31

What're the types of stereo cortical cells?

Answer 31

Course stereo and fine stereo cells

Question 32

What're the course cells?

Answer 32

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

Question 33

What's responsible for the magic eye effect?

Answer 33

Course cells

Question 34

What percentage of stereo cells does course cells make up?

Answer 34

30%

Question 35

What do fine stereo cells do?

Answer 35

Needle threading stereopsis

Question 36

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

Answer 36

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

Question 37

What percentage of stereo cells is tuned excitatory?

Answer 37

50%

Question 38

What percentage of stereo cells is tuned inhibitory

Answer 38

20%

Question 39

What happens with short term abuse of visual system?

Answer 39

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

Question 40

What happens with long term abuse of the visual system?

Answer 40

Amblyopia! Can be meridional | If certain oriented edge detectors aren't stimulated, will also switch directions