Exam 3 Week 14 ppt 5 visual cortex

Question 1

Brodman’s areas of visual cortex

Answer 1

–Foveal area (1) most posterior
–Peripheral areas more rostral (2 & 3)

Question 2

Where does visual pathway end retinotopically?

Answer 2

around the calcarine sulcus of the primary visual cortex

Question 3

Where do some axons of the optic radiation terminate?

Answer 3

visual association cortex

Question 4

How is visual cortex organized?

(draw/imagine a picture)

Answer 4

functional columns

Question 5

Functional columns- principle LGN input to ____

Answer 5

layer IV

Question 6

Matrix of overlapping columns
(name the three columns)

Answer 6

–Ocular dominance columns
–Orientation columns
–Blobs

Question 7

Ocular dominance columns- 3 points to know

Answer 7

1. Respond with preference to right or left eye
2. Largest of column structures
3. Alternating eye dominance

Question 8

Orientation columns- 2 points to know

Answer 8

1. Contain simple & complex cells don’t respond to points of light but bars of light only in certain orientations
2. Adjacent columns related but different orientation

Question 9

What do simple cells do?

Answer 9

• Respond to bars of light only in a certain orientation with inhibitory surround
• Convergence of LGN cells

Question 10

What do complex cells do?

Answer 10

1. Respond to bars of light only in a certain orientation but not have inhibitory surround
2. respond with movement of the bar of light in one direction
3. represent summation of several simple cells

Question 11

What does MaryBeth wish she were doing right now?

Answer 11

Recieving a massage and then eating some pizza

Question 12

Where are blob columns located?

Answer 12

–Located in layers II & III
–Divided into blobs & interblob regions

Question 13

Purpose of blob columns

Answer 13

–Blobs for color processing
–Interblob regions for form processing

Question 14

What is the Modular Organization of the visual cortex?

Answer 14

–2x2 mm areas of 1° visual cortex
–Each Module contains a

• 360° of orientation columns
• Set of of left & right ocular dominance columns
• Set of 16 blobs & interblob regions for color and form discrimination

–Each module is interconnected with adjacent modules

Question 15

Binocular organization

Answer 15

–Layer IV cells of a single ocular dominance column are monocular
–Interconnections between adjacent columns and layers produces binocular vision

Question 16

Brodmann’s areas for visual association cortex and subdivision

Answer 16

Brodmann areas 18 & 19 and is divided into pre-striate cortex (V2) and Extra-striate (V3)

Question 17

Pre-striate cortex – V2 (5 points to know)

Answer 17

1. Complete map of the visual world
2. More complex orientation, spatial frequency, and color characteristics than the primary cortex
3. Response to illusory contours
4. Respond to whether the stimulus is part of the figure or the ground
5. part of Attentional modulation

Question 18

Extra-striate cortex – V3 (2 points to know)

Answer 18

1. Global motion
2. Parts of dorsal & ventral streams

Question 19

Why do I care about Figure-Ground relationships?

Answer 19

allow us to detect objects from their background. It also gives us a form of visual illusion

Question 20

Where is the Dorsal Stream?

Answer 20

Projections from area 18 visual association cortex to the parieto-occipital cortex (posterior parietal cortex)

Question 21

Importance of dorsal stream

Answer 21

–Important for analyzing motion and spatial orientation within the visual field navigate around it, and manipulate objects within it

Question 22

What happens if there is damage to dorsal stream?

Answer 22

Damage in this area produces visual apraxia:

• an object is seen, and identified, but cannot be used.
• Functional significance is lost
• Example can identify a comb by sight, but cannot pick it up and comb hair

Question 23

Where is the ventral stream?

Answer 23

Projections to the occipito-temporal cortex and inferior temporal cortex for

1. identification of the object
2. identification of complex stimuli such as faces
3. further verbal manipulation

Question 24

Damage to ventral stream results in ______

Answer 24

• visual agnosia – inability to name an object even though it is seen
• produces prosopagnosia, the inability to identify people by their faces