Visuoconstructive Functioning Flashcards

1
Q

Visual Agnosia

A

Inability to recognize familiar objects not related to loss of visual acuity – familiar objects can be seen but not recognized

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2
Q

Prosopagnosia

A

special case of agnosia in which recognition deficits specific to faces

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3
Q

Object Vision Pathway

A

VENTRAL; primary visual cortex; secondary visual cortex; inferior longitudinal fasciculus; posterior inferotemporal cortex

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4
Q

Spatial Vision Pathway

A

DORSAL; superior longitudinal fasciculus;; posterior parietal lobe

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5
Q

Temporal route

A

important for recognizing objects

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6
Q

Parietal route

A

important for spatial location of objects

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7
Q

Monkey Double Dissociation

A

temporal lobe- impaired time in object discrimination but could do the spatial task
parietal lobe- could not do spatial task as quickly but could do object recognition

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8
Q

Methods of Monkey Double Dissociation?

A

Monkeys had to either learn to choose an unfamiliar object or choose object nearest a “landmark”–> removed parts of brain in either temporal or parietal lobe–> dictated the difficulties in performance

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9
Q

Parietal lobe neurons

A

60% of neurons are responsive to peripheral (non-foveal) parts of visual field–> spatial location

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10
Q

Temporal lobe neurons

A

receptive field always includes fovea; differential sensitivity to various objects; 41% excited by various stimuli, 59% demonstrated selectivity

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11
Q

How are objects defined?

A

object constancy; color & texture; variability in sensory information

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12
Q

object constancy

A

recognize objects in infinite orientations

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13
Q

color & texture

A

even when inappropriate, still able to recognize things

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14
Q

variability in sensory information

A

viewing position; distance from retina (size constancy even though they appear different sizes bc of distance); rarely seen in isolation

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15
Q

Viewer centered recognition

A

perception depends on recognizing objects from a variety of perspectives: stored representations for each perspective, match templates in memory to stimulus

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16
Q

Problems with viewer centered recognition

A

need template for each object, need multiple templates for each object, driven by a single cell (grandmother cells &; gnostic units), loss of cell, novel objects

17
Q

grandmother cells

A

coined to convey the notion that recognition arises from the activation of neurons that are finely tuned to specific stimuli

18
Q

gnostic unit

A

type of neuron that can recognize a complex object (Greek “of knowledge”), cell (or cells) signal the presence of a known stimulus

19
Q

object-centered recognition

A

sensory input gives basic properties: objects defined on relationship among basic properties; major/minor axis

20
Q

object-centered recognition occurs by parts

A

basic building blocks analyzed; ensemble hypothesis says recognition results from specific combination of core features; explains confusion of visually similar objects; allows for recognition of novel objects

21
Q

geons

A

attempts to try and define building blocks

22
Q

apperceptive visual agnosia

A

failure in object recognition with basic visual functions (acuity, color, motion) preserved; difficulty with copying; deficits in object constancy;

23
Q

how to test for apperceptive visual agnosia?

A

unusual views test; incomplete figures test—> difficulty with perceptual categorization, thus cannot recognize from usual views based on constancy

24
Q

associative agnosia

A

not attributed to perceptual difficulties; can copy & perform subtle shape discriminations; can perform unusual views test; still can’t name it

25
Warrington Model
left hemisphere systems: semantic categorization & visual analysis; right hemisphere systems: perceptual categorization & visual analysis
26
lesion in left-hemisphere causes?
associative agnosia
27
lesion in right-hemisphere causes?
apperceptive agnosia
28
problem with warrington model
fails to capture difficulty with integration
29
integrative agnosia
to recognize objects, individuals examine each piece in isolation and put together; appears to be a core deficit underlying many agnosias
30
Behrmann et al 2006
These results suggest that encoding the spatial arrangements of parts of an object requires a mechanism that is different from that required for encoding the shape of individual parts, with the former selectively compromised in integrative agnosia
31
prosopagnosia
isolated deficits in facial recognition
32
damage causing prosopagnosia
most frequent following bilateral lesions; possible following right lesions; rare following left lesions; tend to be focused in occipital temporal regions