Ventral and Dorsal Stream (M2) Flashcards

1
Q

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

A
  1. head-centered coordinate system

2. dorsal stream

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2
Q

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

A
  1. left hemisphere lesion, often left occipital and/or adjacent splenium
  2. disconnect occipital cortex from posterior language areas (esp. left angular gyrus)
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3
Q

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

A
  1. identify grating orientation
  2. recognize letters and numerals visually
  3. recognize line drawings of common objects, including ones she had drawn herself
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4
Q

What stream is responsible for mental rotation of letters?

A

dorsal stream

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5
Q

What is spared in pure alexia?

A
  1. ability to write
  2. ability to understand spoken language
  3. ability to read letter-by-letter
  4. ability to recognize and interpret pictures
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6
Q

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

A
  1. no

2. yes

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7
Q

What is the inability to recognize faces called?

A

prosopagnosia

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8
Q

What stream is responsible for passive letter viewing?

A

ventral stream

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9
Q

What is the roles of V4 in visual perception?

A
  1. some color perception
  2. object perception (non-sophisticated)
  3. gateway to higher ventral stream locations
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10
Q

What type of functions does the ventral stream contain?

A

Static:

  1. pattern recognition
  2. scrutiny of fine detail
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11
Q

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

A
  1. appreceptive agnosia
  2. to form a coherent percept of a stimulus
  3. anoxia from carbon monoxide poisoning
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12
Q

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

A
  1. oculocentric coordinate system

2. superior colliculus

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13
Q

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

A
  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)
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14
Q

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

A
  1. lateral occipital cortex
  2. V4
  3. inferotemporal cortex
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15
Q

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

A

pure alexia

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16
Q

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

A
  1. allocentric coordinate system

2. ventral stream

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17
Q

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

A
  1. V1 to V4 to infero-temporal cortex

2. parvo

18
Q

What is spared in prosopagnosia?

A
  1. recognition of common objects
  2. recognition of one’s own handwriting
  3. able to copy pictures
19
Q

What are the major locations that the retina projects to?

A
  1. dorsal LGN of the thalamus
  2. pulvinar of the thalamus
  3. superior colliculus of the optic tectum
20
Q

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

A
  1. inferotemporal cortex

2. left pre-motor area

21
Q

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

A

perceived direction of stimulus motion

22
Q

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

A
  1. could not identify or match orientation of slot

2. could place card into slot smoothly and normally

23
Q

What major higher ventral stream locations does V4 project to?

A
  1. inferotemporal cortex pattern recognition area
  2. fusiform face area
  3. parahippocampal place area
  4. wordform area
24
Q

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

A
  1. V1 to MT/V5 to posterior parietal cortex

2. magno

25
Q

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

A

dorsal takes attention from ventral

26
Q

How are the cells of the MT organized?

A

in motion opponent fashion

27
Q

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

A
  1. egocentric coordinate system

2. dorsal stream

28
Q

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

A
  1. sluggish and sustained
  2. all visible spatial frequencies (including high)
  3. color opponent and luminance channels
  4. mostly central
29
Q

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

A

delay-and-compare circuit

30
Q

Where is the lesion located in object agnosia?

A

shape area of brain

31
Q

Is the ability to recognize faces hereditary or developmental?

A

hereditary

32
Q

What is often the cause of a pure alexia?

A

infarct to the left posterior cerebral artery

33
Q

What type of functions does the dorsal stream contain?

A

dynamic:

  1. perception of motion
  2. guidance of motor behavior
  3. attracting attention for closer scrutiny
34
Q

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

A
  1. pure alexia (left hemisphere) and/or

2. prosopagnosia (right hemisphere)

35
Q

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

A
  1. brisk and transient
  2. mostly low frequency
  3. only luminance
  4. mostly peripheral
36
Q

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

A
  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)
37
Q

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

A
  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
38
Q

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

A

object agnosia

39
Q

What does damage to the ventral system disturb?

A
  1. object recognition
  2. visual memory
  3. relationship between objects (allocentric coordinate system)
40
Q

Where is the location of the lesion in a prosopagnosia?

A

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