Block 12 Flashcards

1
Q

The extrastriate cortex contains how many visual areas

A

20

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2
Q

There is feedback information from higher cortical areas to lower cortical areas via

A

Reciprocal connections

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3
Q

T/F visual information flows along distinct but not independent processing streams

A

True

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4
Q

Temporal/ventral/what stream is critical for

A

Identifying and recognizing objects

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5
Q

Dorsal/parietal/where stream is critical in

A

Motion perception
Localization in visual space
Action organization

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6
Q

Dorsal-dorsal stream

A

Processes action information

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7
Q

Damage to the dorsal-dorsal stream results in

A

Optic ataxia

They cannot point to or reach for a visual target

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8
Q

What is the ventral-dorsal stream

A

It includes MT/V5

Appears to play a role in space perception and action organization

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9
Q

The parvo pathway has strong input to this processing stream

A

Ventral

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10
Q

Magno pathway has strong input to this processing stream

A

Dorsal

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11
Q

T/F the two recessing streams communicate with each other

A

True

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12
Q

V4 reveals an abundance of cells with chromatic sensitivities. What does this mean

A

It is well adapted for color perception

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13
Q

Cells in the inferotemporal cortex respond to complex forms,
What does this include

A

Faces

Form perception

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14
Q

V4 and IT are part of this processing stream

A

Ventral

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15
Q

Cells of the MT and V5 are a part of this processing stream

What do they do?

A

Dorsal stream

Encode motion

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16
Q

What does PET show

A

Radioactive tracer is used to observe changes in blood flow-indicative of increased cortical metabolism

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17
Q

What does fMRI show

A

Better resolution that PET

Shows cortical activity by detecting levels of oxygenation

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18
Q

If a person looks at a screen of colored moving objects and is asked to stare a green object, what stream will be activated

A

Ventral

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19
Q

If a human is looking at a shape of form what stream will be active

A

Ventral

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20
Q

If a human is looking at movement of objects what stream is active

A

Dorsal

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21
Q

T/F information from teh various cortical areas must be synthesized to result in an integrated perception

A

True

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22
Q

What is responsible for the coordination of the processing streams

A

Pre-frontal Cortex

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23
Q

Cells which region(s) can analyze motion

A

MT

V5

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24
Q

To study global motion perception what test is used

A

Random dot kinematograms

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25
T/F in MT/V5 it is more active when viewing a moving object rather than a stationary one
True
26
What is motion aftereffect
It is a motion illusion that occurs in the absence of motion They result from adaptation of direction-specific motion detectors . The adapting stimulus reduces sensitivity to its direction of movement This causes subsequently viewed stationary stimuli to appear to move in the opposite direction
27
Where are the motion detectors responsible for motion aftereffect located
In the cortex | This is the first site for substantial interaction between the 2 eyes
28
The receptive fields of IT are small or large?
Large
29
What does the large receptive field of IT cells provide
Basis to integrate information over an extensive area and analyze complex patterns They respond best to comparatively sophisticated shapes
30
The IT region in monkeys is equivalent to this in humans
Lateral occipital complex (LOC)
31
What does teh LOC respond best to
Objects, but not scrambled objects or object fragments Responds to all objects, and does not show selectivity for a particular type of object
32
Fusiform face area (FFA) responds to
Faces, but not other objects May be involved in face detection and/or recognition
33
Parahippocampal place area (PPA) recognizes
Objects and places, but not faces | May play a role in perceiving scenes
34
T/F the areas that process faces (FFA) and color (V4) are far apart
False, they are close in proximity
35
What is prosopagnosia
The inability to recognize faces
36
What is cerebral achromatopsia
Inability to distinguish hues
37
What is top-down attention
You can direct your attention to the words you are reading You device what you want to pay attention to It is volitional
38
What is bottom up visual attention
Caused by an external stimulus | Your attention is suddenly shifted
39
How does serial processing affect visual attention
You direct your spot light of attention on each object of interest to see if it is available
40
What is change blindness
A phenomenon in which you cannot readily see the differences between two images
41
What can make changes between images more visible
Sequential presentation may trigger our exogenous attention. Makes the changes immediately obvious When the two images are presented simultaneously the difference between them do not as readily elicit attention
42
Top-down attention can stimulate what area
V4
43
Lesions of the striate cortex produce
Blind spots
44
Extra striate lesions can cause
Visual agnosias They wont be able to recognize objects There can be different forms depending on the area damaged
45
What is object agnosia
Can’t recognize real objects
46
What is agnosia for drawings
You cant recognize drawn objects
47
What is prosopagnosia
Can recognize faces
48
What is simultagnosia
Perception of more than one object
49
What is color agnosia
Can’t associate colors with objects
50
What is color anemia
Can’t name colors
51
What is cerebral achromatopsia
Can’t distinguish hues
52
What is visual spatial agnosia
Can’t do Stereoscopic vision, or topographical relations
53
What is cerebral akinetopsia
Can’t perceive motion
54
In akinetopsia what is damaged
Dorsal processing stream | They will have normal VF, VA, and color vision
55
What is happening in the patients with cerebral achromatopsia
They have a normal complement of cones, but they are unable to distinguish hues because of an extra striate lesion They could see color prior to lesion See world as black and white
56
What is hemineglect syndrome
They only see one side, either right or left, and they ignore the other side. This occurs secondary to a lesion in the superior temporal lobe
57
What is simultagnosia
They patient cannot perceive more than one object at a time May be present in Balint’s syndrome (bilateral damage to parietal lobes)
58
What is synesthesia
Very rare Cortical modulates are abnormally linked to each other. So stimulation of one sense leads to activation of another (Seeing a letter or number results in perception of a color)
59
What is phantom vision
In patients with visual loss to experience visual hallucinations
60
What is Charles Bonnet Syndrome
15% of visually impaired patients Hallucinations that take form of a person (can be other forms as well) Images are sharply focused and Vivid Patient recognizes that they are not real The hallucinations do not bother the patients
61
What is the importance of perceptual learning
Can be used to improve amblyopia and near VA in children with low vision Can ameliorate certain age-related declines in visual performance
62
What is electrodiagnosis used for
To confirm normal functional status Test infants and unresponsive patients Monitor for development of drug toxicity Detect sub-clinical disease Detect early functional loss in progressive disease Detect carrier state disease Discriminate level of deficit Monitor progression/resolution of condition
63
A wave of ERG
From photoreceptors
64
B wave
From bipolar layer and depolarization of Mueller cells
65
What is the c wave in ERG
RPE
66
Why isn’t a full field ERG used for maculopathies?
A small area of retina is affected