Ventral and Dorsal Stream (M2)

Question 1

What is the spatial location system that is where things are relative to the head? 1. What area of the brain is this? 2

Answer 1

1. head-centered coordinate system

2. dorsal stream

Question 2

What is the location of the lesion in a pure alexia? 1. What does it disconnect? 2

Answer 2

1. left hemisphere lesion, often left occipital and/or adjacent splenium
2. disconnect occipital cortex from posterior language areas (esp. left angular gyrus)

Question 3

For a person with appreceptive agnosia, what are the things that she could NOT recognize or do?

Answer 3

1. identify grating orientation
2. recognize letters and numerals visually
3. recognize line drawings of common objects, including ones she had drawn herself

Question 4

What stream is responsible for mental rotation of letters?

Answer 4

dorsal stream

Question 5

What is spared in pure alexia?

Answer 5

1. ability to write
2. ability to understand spoken language
3. ability to read letter-by-letter
4. ability to recognize and interpret pictures

Question 6

Are object agnosia patients able to draw an object from memory? 1. Copy an object? 2

Answer 6

1. no

2. yes

Question 7

What is the inability to recognize faces called?

Answer 7

prosopagnosia

Question 8

What stream is responsible for passive letter viewing?

Answer 8

ventral stream

Question 9

What is the roles of V4 in visual perception?

Answer 9

1. some color perception
2. object perception (non-sophisticated)
3. gateway to higher ventral stream locations

Question 10

What type of functions does the ventral stream contain?

Answer 10

Static:

1. pattern recognition
2. scrutiny of fine detail

Question 11

What is the condition that is due to deafferentation of the ventral system? 1. What are they unable to do? 2. What is usually the cause of this? 3

Answer 11

1. appreceptive agnosia
2. to form a coherent percept of a stimulus
3. anoxia from carbon monoxide poisoning

Question 12

What is the spatial location system that is where the world is relative to the eye? 1. What area of the brain is this? 2

Answer 12

1. oculocentric coordinate system

2. superior colliculus

Question 13

What are the major ways that motion is important to aspects of visual perception?

Answer 13

1. figure/ground segregation (camo)
2. perception of 3D space
3. perception of 3D scene (induced motion)
4. perception of self-motion (train)
5. perception of change (time-lapse photo)

Question 14

What are the areas of the brain that respond better when viewing “nonsense object” than “noise”?

Answer 14

1. lateral occipital cortex
2. V4
3. inferotemporal cortex

Question 15

What is the inability to read words in the presence of intact letter recognition and intact writing?

Answer 15

pure alexia

Question 16

What is the spatial location system that is where things are relative to each other? 1. What area of the brain is this? 2

Answer 16

1. allocentric coordinate system

2. ventral stream

Question 17

What is the pathway of the ventral stream? 1. What type of cells are these mostly? 2

Answer 17

1. V1 to V4 to infero-temporal cortex

2. parvo

Question 18

What is spared in prosopagnosia?

Answer 18

1. recognition of common objects
2. recognition of one’s own handwriting
3. able to copy pictures

Question 19

What are the major locations that the retina projects to?

Answer 19

1. dorsal LGN of the thalamus
2. pulvinar of the thalamus
3. superior colliculus of the optic tectum

Question 20

What are the areas of the brain that respond better when naming “tools” than when viewing “nonsense”?

Answer 20

1. inferotemporal cortex

2. left pre-motor area

Question 21

What do the cells in the MT of the brain respond to?

Answer 21

perceived direction of stimulus motion

Question 22

For a person with appreceptive agnosia, what are their results from the “posting” experiment?

Answer 22

1. could not identify or match orientation of slot

2. could place card into slot smoothly and normally

Question 23

What major higher ventral stream locations does V4 project to?

Answer 23

1. inferotemporal cortex pattern recognition area
2. fusiform face area
3. parahippocampal place area
4. wordform area

Question 24

What is the pathway of the dorsal stream? 1. What type of cells are these mostly? 2

Answer 24

1. V1 to MT/V5 to posterior parietal cortex

2. magno

Question 25

Which stream has the ability to attract your attention away from what is happening with the other stream?

Answer 25

dorsal takes attention from ventral

Question 26

How are the cells of the MT organized?

Answer 26

in motion opponent fashion

Question 27

What is the spatial location system that is where things are relative to the body? 1. What area of the brain is this? 2

Answer 27

1. egocentric coordinate system | 2. dorsal stream

Question 28

For parvo cells, what is their temporal ability? 1. Spatial ability? 2. Color ability? 3. Visual field area? 4

Answer 28

1. sluggish and sustained 2. all visible spatial frequencies (including high) 3. color opponent and luminance channels 4. mostly central

Question 29

What is the primary circuit for extracting motion information from the stimulus?

Answer 29

delay-and-compare circuit

Question 30

Where is the lesion located in object agnosia?

Answer 30

shape area of brain

Question 31

Is the ability to recognize faces hereditary or developmental?

Answer 31

hereditary

Question 32

What is often the cause of a pure alexia?

Answer 32

infarct to the left posterior cerebral artery

Question 33

What type of functions does the dorsal stream contain?

Answer 33

dynamic: 1. perception of motion 2. guidance of motor behavior 3. attracting attention for closer scrutiny

Question 34

If a patient has object agnosia, what other associative agnosias will they have (and which brain hemisphere is this located in)?

Answer 34

1. pure alexia (left hemisphere) and/or | 2. prosopagnosia (right hemisphere)

Question 35

For magno cells, what is their temporal ability? 1. Spatial ability? 2. Color ability? 3. Visual field area? 4

Answer 35

1. brisk and transient 2. mostly low frequency 3. only luminance 4. mostly peripheral

Question 36

For a person with appreceptive agnosia, what are the things that she could do involving there visuomotor capabilities?

Answer 36

1. reach and grasp common objects easily and well (egocentric) 2. catch a ball thrown towards her (egocentric) 3. walk around obstacles in the environment (egocentric) 4. follow a light with her eyes (oculocentric)

Question 37

For a person with appreceptive agnosia, what are the things that she could recognize or do?

Answer 37

1. recognize letters and numeral by touch 2. recognize common objects by touch 3. write letters and numerals from dictation 4. draw objects from memory

Question 38

What is the inability to recognize objects in the presence of intact ability to detect them and their features?

Answer 38

object agnosia

Question 39

What does damage to the ventral system disturb?

Answer 39

1. object recognition 2. visual memory 3. relationship between objects (allocentric coordinate system)

Question 40

Where is the location of the lesion in a prosopagnosia?

Answer 40

inferior occipito-temporal cortex that is always in the right hemisphere and often have homologous left hemisphere lesion