Central Visual Processing I

Question 1

How many layers are in the LGN? How are these layers divided?

Answer 1

6 layers
2 are magno (ventrally) and 4 are parvo (dorsally) with konio layers interspersed between
From ventral to dorsal: Contra-Ips-Ips-Contra-Ips-Contra

Question 2

How many layers are there in VI?

Answer 2

6

Question 3

What layer of V1 does the LGN enter into?

Answer 3

Layer 4

Question 4

The part of the visual field that a given neuron responds to within the visual cortex is defined as:

Answer 4

Receptive field

Question 5

The mapping of a visual input from the retina to V1 is defined as:

Answer 5

Retinotopy

Question 6

The amount of cortex that is designated to a given part of the visual field depends directly on what?

Answer 6

The density of photoreceptors in the retina

Question 7

The majority of the visual cortex is devoted to what part of the retina?

Answer 7

The fovea which has the greatest density of photoreceptors (especially cones)

Question 8

What are the different names for the visual cortex?

Answer 8

Striate or Brodmann area 17 or V1

Question 9

From the optic tract, axons project into a number of targets. What are some of these targets?

Answer 9

Superior colliculi (important in orienting motion of the head with eye movements)
Pretectum (important for pupillary and lens reflexes)
Hypothalamus (regulation of Circadian rhythms)
Thalmogeniculate nucles (LGN) image processing

Question 10

What is the primary visual processing pathway?

Answer 10

Corticogeniculocortical pathway (LGN)

Question 11

What is the first area that joins the information from both the right and left eye to get binocular vision?

Answer 11

V1

Question 12

There are three different types of cone classes. What are they?

Answer 12

R (long), G (medium), and B (short)

Question 13

Where do the M, P, and K pathways originate? Where do they terminate?

Answer 13

Originate in the retina and terminate in the visual cortex

Question 14

What type of visual information does the M (magna) pathway predominately perceive?

Answer 14

High temporal resolution (speed) and motion

Question 15

What type of visual information does the P (parvo) pathway predominately perceive?

Answer 15

High visual acuity and color

Question 16

What type of visual information does the K (konia) pathway predominately perceive?

Answer 16

Color

Question 17

The LGN received feedback from which layer of V1?

Answer 17

Layer 6

Question 18

True or False: The LGN has center-surround receptor fields

Answer 18

True- just like the retinal ganglia

Question 19

Which layers of V1 go onto the extrastriate (V2)?

Answer 19

Layer 2 and layer 3

Question 20

What is ocular dominance?

Answer 20

The predominant eye that is used to see something a certain receptive field

Question 21

What is orientation tuning? How does this relate to action potentials?

Answer 21

Neuron is stimulated by the edge of light when the light is presented at an optimum angle, which produces more action potentials

Question 22

Some V1 neurons aren’t orientation tuned but rather have receptive fields that allow them to be color selective. What are the two different color signals?

Answer 22

1. Red- Green

2. Blue-Yellow

Question 23

True or False: V1 neurons have center-surround receptive fields?

Answer 23

False: with the exception of the neurons responding only to color

Question 24

Every V1 neuron has three different components that make it unique: what are these components?

Answer 24

A specific receptive field position (retinopy), an ocular dominance, and a orientation position

Question 25

What do CO blobs that are interspersed between the orthogonal columns of ocular dominance and orientation position represent? What types of vision do these CO blobs perceive?

Answer 25

Long term metabolic activty | CO blobs perceive monocular, color vision

Question 26

A collection of functional cortical columns that covers the entire range of possible values of a given stimulus parameter is the definition for what term?

Answer 26

Hypercolumn

Question 27

All of the orientation positions for a given point in visual space is the definition for what term?

Answer 27

Orientation hypercolumn

Question 28

A complete orientation cycle- or one orientation hypercolumn, takes up how much distance within V1?

Answer 28

1mm

Question 29

A complete set of cortical columns handling both the right and left eye for a given point in visual space is the definition for what term?

Answer 29

Ocular dominance hypercolumn

Question 30

A complete ocular dominance hypercolumn requires how much distance within the VI?

Answer 30

1mm

Question 31

If you were to cut out a 1mm x 1mm chunk of VI, what would this give you?

Answer 31

All of the possible orientations that can be seen through both eyes for a given point in the visual field

Question 32

What are the two major processing pathways from V2?

Answer 32

1. Dorsal pathway | 2. Ventral pathway

Question 33

What is the dorsal pathway responsible for? What does it connect?

Answer 33

Motion and location (the where) | Connects V2 to the parietal visual cortex

Question 34

What is the ventral pathway responsible for? What does it connect?

Answer 34

``` Pattern recognition (the what) Connects V2 to the temporal visual cortex ```

Question 35

How are CO different in V2 than in VI?

Answer 35

In V2 CO are stripes, in VI CO are blobs

Question 36

The thin stripes due to the CO blobs in VI, contain cells for what kind of vision in V2?

Answer 36

color

Question 37

The pale stripes due to interblobs in VI, contain cells for what kind of vision in V2?

Answer 37

Detection of curvature

Question 38

The thick stripes of V2 contain cells for what kind of vision?

Answer 38

Depth perception

Question 39

What is more retinotopically oriented: VI or V2?

Answer 39

VI

Question 40

As you move up the higher extrastriate layers, what happens to the retinotopy and the receptive field?

Answer 40

Retinotopy decreases while the receptive field increases

Question 41

What are the four layers of ordering in V1?

Answer 41

Retinotopy, ocular dominance, orientation, and CO blobs

Question 42

A bilateral lesion of the temporal lobe will result in what with regard to higher vision?

Answer 42

Inability to discriminate between objects

Question 43

A bilateral lesion of the parietal lobe will result in what with regard to higher vision?

Answer 43

Inability to discriminate locations