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Foundations Final > Visuospatial Processing > Flashcards

Visuospatial Processing Flashcards

1
Q

Higher cognitive functions

A

IQ, achievement level “fund of information”, abstract reasoning/problem solving/concept formation, social cognition, calculations, sequencing

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2
Q

Hecaen’s Classification of Acalculias

A
  1. Alexia and agraphia for numbers
  2. Spatial acalculia
  3. Nonspecific (secondary to mem probs, dementia, etc)
  4. Developmental
  5. Slowed processing (often with CHI)
  6. Anarithmetria
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3
Q

3 visual pathways

A
  1. retina –> optic nerve (CN2) –> thalamus (LGB/LGN) –> occipital lobe. carries info about color, form, motion, and depth
  2. retina –> optic nerve –> superior colliculus. Carries info about location of visual stimulus (old pathway)
  3. retina –> optic nerve –> suprachiasmatic nucleus. Carries information about lightness & darkness.
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4
Q

suprachiasmatic nucleus

A

nucleus in the hypothalamus; in vision, receives information about lightness and darkness; relates to sleep/wake cycles

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5
Q

V1

A

primary visual cortex; earliest cortical visual area, AKA striate cortex

specialized for processing info about static and moving objects; excellent in pattern recognition

contains retinotopic map of spatial information, with “cortical magnification” of the fovea

Neurons here have smallest receptive field

with binocular vision, alternating neurons tuned to right and left eyes

Neurons with smaller receptive fields tend to cluster in columns

upper bank of calcarine sulcus responds to lower visual field & vice versa

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6
Q

Line of gennari

A

(also called the “band” or “stria” of Gennari) is a band of myelinated axons that run parallel to the surface of the cerebral cortex on the banks of the calcarine fissure in the occipital lobe. This formation is visible to the naked eye as a white strip running through the cortical grey matter, and is the reason the primate V1 is also referred to as “striate cortex.” The line of Gennari is due to dense axonal input from the thalamus to layer IV of visual cortex. Although non-primate species have areas that are designated primary visual cortex, some (if not all) lack a stria of Gennari.

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7
Q

V2

A

Visual association area (1st region within association area)

  • receives strong feedforward connections from V1 and sends strong connections to V3, 4, 5
  • Cells attuned to orientation, spatial frequency, and color
  • 1st area affected by attention
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8
Q

V3 & 3a

A

Specialized to process FORM

  • dorsal V3 is part of dorsal stream (receives input from V1 & 2 and projects to posterior parietal cortex)
  • Ventral V3 is part of ventral stream
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9
Q

V4

A

Part of ventral stream; sensitive to line orientation and color; contains fusiform gyrus; sensitive to attention

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10
Q

V5

A

(MT) in humans) = posterior middle temporal gyrus at the border of the occipital lobe. Sensitive to motion

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11
Q

Visual pathway for form

A

retina –> LGN (parvocellular layers) –> V1 (layer 4B) –> BOTH V2 & V3… V2 also projects to V3

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12
Q

Visual pathway for form + color

A

retina –> LGN (parvocellular layers) –> V1 (layers 2/3) –> BOTH V2 & V4 … V2 also projects to V4

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13
Q

Visual pathway for color

A

retina –> LGN (parvocellular layers) –> V1 (layers 2/3) –> BOTH V2 and V4 (fusiform gyrus) … V2 also projects to V4

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14
Q

Visual pathway for motion

A

retina –> LGN (magnocellular layers) –> V1 layer 4b –> BOTH V2 & V5 (MT) … V2 also projects to V5

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15
Q

Motion

A

V5 and through thick stripes of V2

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16
Q

Color

A

V4 (& through thin stripes of V2)

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17
Q

Color + Form

A

V4 (interstripes of V2)

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18
Q

Form

A

V3 (thick stripes of V2)

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19
Q

Achromatopsia

A

Lesion to V4 results in loss of color perception, as well as loss of MEMORY of color.

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20
Q

Hemiachromatopsia

A

Lesion to V4 in only one hemisphere; results in loss of color perception for half of visual field

21
Q

Chromatopsia

A

Condition in which ONLY color is perceived; can occur with carbon monoxide poisoning

22
Q

Akinetopsia (aka motion blindness)

A

Objects can only be seen when they are at rest; condition results from lesion to V5, which is responsible for perception of movement

23
Q

Dorsal Stream

A

“how/where pathway” - - SPATIAL processing; housed in parietal lobes

  • location
  • movement
  • spatial transformations
  • spatial relations
24
Q

Ventral Stream

A

“what pathway” - - OBJECT processing; only pathway fooled by visual illusions

  • color
  • texture
  • pictorial detail
  • shape
  • size
25
Q

parietal lobes

A

home of dorsal stream
Processes HOW motor acts must be performed (e.g., picking up a pen)
- dorsal stream supports spatial processing of info; projects from primary visual area to parietal regions
- Cells in parietal areas 5 & 7 are sensitive to attributes that allow stable cognitive maps to be made

26
Q

frontal lobes

A

dorsal premotor cortex is involved in short-term visuospatial memory (confirmed via lesion studies)

  • however, parietal areas are interconnected & active during visuospatial working mem tasks
  • visuospatial WM depends on dorsal stream and its connections to frontal lobe
  • Guides and plans movements
27
Q

Temporal lobes

A

Ventral stream
Hippocampal formation is involved in spatial learning
- we find larger hippocampi in animals who cache (also larger depending on season)
- Damage to hippocampus in rats impairs their ability to learn mazes
- damage results in inability to form new memories of places, produce memories about location
- cells in HC respond preferentially and selectively to spatial locations and form the basis for memories about space

cortical association areas –> entorhinal cortex –> hippocampus (which integrates information)

28
Q

Binding problem

A

How do we integrate visual information into a single percept?

  • Info from prestriate cortex areas flows to dorsal and ventral streams, carrying different types of information
  • connections between adjacent areas and feedback loops facilitate our ability to “bind” visual info
29
Q

Benton’s Classification of Visual Disturbances

A
  1. Visuoperceptual : visual object agnosia, apperceptive agnosia, associative agnosia, prosopagnosia, color anomia
30
Q

Visual object agnosia

A

impairment in object recognition in the presence of intact vision, memory, and intellectual function.

  1. Apperceptive
  2. Associative
31
Q

Apperceptive agnosia

A

Inability to synthesize features into object; may be associated with denial of deficit

good visual acuity, color perception, brightness/contrast discrimination, motion detection

poor shape discrimination

Associated with diffuse brain damage (often carbon monoxide related) and aphasia… it’s been proposed that language may mediate the synthesis of visual info into perceptual objects

32
Q

Associative agnosia

A

Disconnection between visual representations and areas of brain responsible for language and memory, or stored visual memories damaged

  • perception is spared
  • can identify objects by touch or description alone - general object knowledge is intact, but inability to access perceptual knowledge semantically
  • NOT just a naming deficit; individuals also cannot pantomime or sort objects by function
  • Recognition impairment can occur primarily for
    1. objects (with bilateral damage)
    2. Faces (with right hemisphere damage)
    3. Printed word (with left hemisphere damage)
33
Q

Prosopagnosia

A

Inability to recognize familiar faces - often accompanied by recognition difficulty of familiar buildings, landscapes, automobiles.

Are faces special?
- most people with prosopagnosia can also recognize gait, voice, clothing, age, gender, race, and emotional expression.

Identity alone is disturbed.

  • SOME people with prosopagnosia can only match unfamiliar faces.
34
Q

Color Anomia

A

impairment in which patients can discriminate shades, list the colors of common objects (suggesting intact general color knowledge), but cannot name color in field of vision

  • associated with alexia without agraphia
35
Q

Visuospatial Deficits (according to Benton’s classifications)

A
  1. defective localization of points in space (associated with parieto-occipital lesions)
  2. defective judgment of direction and distance (posterior parietal lesions in RH) - poor depth perception, R-L discrimination, mental rotation, clock hand placement
  3. Defective topographical orientation (requires RH lesion) - unable to recall memories of spatial layouts, maps. associated with left neglect
  4. Unilateral visual neglect
36
Q

Visuoconstructive Deficits (according to Benton’s classifications)

A
  1. Defective assembling performance; can be due to damage in either hemisphere. Tested with block design, puzzles & drawings
  2. Defective graphomotor performance - often due to left parietal damage (angular gyrus) - not apraxia
  • copy vs. command may parallel parietal vs. temporal lobe deficits
37
Q

Visual closure deficits

A

inability to identify/recognize a symbol or object when only a part of the object is visual

38
Q

ventral simultagnosia

A

impaired recognition of the meaning of a whole picture or multiple objects with preserved ability to describe its parts; associated with damage to left inferior temporo-occipital regions

39
Q

dorsal simultagnosia

A

Only able to perceive one thing at a time; may bump into things, be unable to localize them. Associated with bilateral parieto-occipital regions

40
Q

Capgras Syndrome

A

Sight of loved one results in imposter delusion. may be due to disconnection between visual areas and limbic areas
- vulnerable to reduplication (looking at pics of someone from another angle, a patient can be convinced it is a new person)

41
Q

Cotard’s

A

Delusion that one is dead; may be an extreme form of caprgras; may show low galvanic skin responses to everything

42
Q

Micro & macro somatagnosia

A

Perception of body part as larger or smaller than it truly is (occurs most commonly with seizures - transient)

Sometimes happens with auras in migraines

Temporal lobes suspected, but not confirmed

43
Q

autopagnosia

A

Inability to point to body parts on one’s self (loss of spatial knowledge of one’s own body)

still able to recognize and name body parts

BUT difficulty POINTING to correct body part on command (self or other)

Intact knowledge about the function of body parts, and able to point to clothing items that are associated with certain body parts

44
Q

finger agnosia

A

Inability to recognize, identify or name fingers (can also apply to toes). Often accompanied by LR confusion

finger agnosia + LR confusion + dyscalculia + Agraphia = gerstmann syndrome

45
Q

Gerstmann Syndrome

A
  1. Finger agnosia
  2. LR confusion
  3. Dyscalculia
  4. Agraphia
46
Q

Left-right confusion

A

occurs most commonly in left-handed women

47
Q

Body part phantoms

A

90% of adult amputees experience phantom limbs, but only 10% of children who lose a limb before the age of 6 do.
40% of mastectomy patients report phantoms.

Cause?

48
Q

Anosagnosia

A

denial of disorder/deficit (common in individuals with hemiplegia/unilateralneglect)

Common in RH posterior parietal lesion (commonly related to stroke)

  • Despite lack of conscious awareness of deficit, will often choose tasks based off deficit (i.e., opting for unimanual task over bimanual one)
49
Q

Spatial neglect

A

Failure to report, respond, or attend to stimuli or events in one hemifield (not caused by sensory/motor deficits)

Always on contralesional side

most common with RH damage posterior to central sulcus

Less severe if damage is LH

can test with clock or letter cancellation tasks

usually transient

Foundations Final (2 decks)

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