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3P: Neuro > Visual System > Flashcards

Visual System Flashcards

1
Q

Last stage of visual system where damage causes visual field loss

A

Damage to higher cortical regions of the visual system do NOT result in visual field loss, but instead produce specific impairments in processing of more complex object or spatial information, or can impair awareness of visual space (spatial neglect syndrome, not VF loss)

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2
Q

Unilateral damage to primary visual cortex

A

Homonymous heminopia

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3
Q

Bialteral damage to primary visual cortex

A

Cortical blindness

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4
Q

Clinical syndromes of primary cortex lesions

A

Ischemic damage (infarct) following PCA occlusion (can still spare macula)

Hemonymous hemianopia

If infarc includes ipsilateral selenium, then alexia without a graphia

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5
Q

Loss of abiltiy to read words, typically after PCA infarct

A

Alexia

Comprehnesion of spoken language is intact

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6
Q

Alexia without agraphia

A

Normal abiltiy to write responses to examiners questions

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7
Q

Cortical blindness with ability to identify lines/motion

A

Blindsight phenomenon
-in some patients with cortical blindness, they can correctly guess the form or motion of an object within their VF despite denying “seeing the object”

AKA Riddoch phenomenon

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8
Q

Neuroantaomicl mechanism of blindsight

A

Small percentage of LGN projections that bypass primary visual cortex and project directly ro a higher spatial/motion cortical region called V5

Damage to LGN abolishes blindsight.

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9
Q

Blindsight as potential neuro rehab strategy for partial recovery of vision

A

Some visual system researchers suggest that repeated training and practice with blindsight might potentially promote functional recovery-neural plasticity in the visual system to allow for some VF recovery, either despite permanent damage to V1 or to enhance partial V1 recovery

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10
Q

Achromatopsia

A

Loss of color processing. Patient reports seeing the world in gray. Object form processing/recognition is intact. Damage limited to ventral occipital cortex

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11
Q

Color discrimination

A

Ventral gyri in occipital cortex

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12
Q

Visual agnosia

A

Loss of object recognition. Can see the color and form of an object but does not recognize the whole picture, what the object is or its function

Damage to temporal or occipitotemproal gyri

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13
Q

Prosopagnosia

A

Specific impairment of facial discrimination and recognition, other objects spared. Damage limited to fusiform gyri (anterior to occipitotemproal gyri). Patient can still recognize a person by their voice or other non visual cues

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14
Q

Anomia (anomic aphasia)

A

Recognition without ability to name object/color. Damage to part of broader Wernickes (supramarginal gyrus) or lesion disconnecting the object visual cortex from Wernickes

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15
Q

Neuroanatomy of the dorsal/spatial/motion system

A

Superior parietal lobule

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16
Q

Small or patchy damage to the dorsal/spatial/motion system

A

Produce specific deficits in perception of: position of object in space, size of object, depth perception, detection of motion or direction of motion

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17
Q

Larger area of parietal damage

A

Spatial hemi-neglect

-lack of awareness or attention to half of visual space. Usually the left half. Patient does not perceive any VF loss

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18
Q

Awareness of visual space and spatial neglect syndrome

A
  • usually “hemi-neglect” of left visual space, due to injury on right side. Left side lesion usually does not produce hemi-neglect of right visual space.
  • key region is probably the superior parietal lobule, AKA posterior parietal cortex, but damage to inferior parietal lobule might also be involved
  • not a VF loss: patient denies loss on visual confrontation testin. May detect wiggling inners or object motion on neglected side, but “extinguish” or not notice stimuli on left side if wigging or object motion occurs on both sides simultaneously
19
Q

Basis for predominantly left sided neglect

A
  • left parietal lobe normally attends only tot heright visual spaces; but right parietal lobe normally attends to both sides of visual space
  • thus, with damage to right parietal love, left parietal love supports awareness only of right half of space, producing neglect of left side of space
  • with damage to left parietal lobe, no deficit occurs because right parietal lobe supports awareness of both sides
20
Q

Parietal-temporal occipital region

A

Refers mainly to supramaginal and angular gyri, ala inferior parietal lobule

21
Q

Job of PTO

A

Multi sensory integration. Received input from visual, auditory, and somatosensaory cortex, includes parietal eye field

22
Q

Baling sydnrome

A

Triad of visual and oculomotor deficits

  1. Simultagnosia
  2. Optic ataxia
  3. Ocular apraxia
23
Q

Simultagnosia

A

Difficulty processing/recognizing a complex visual scene from its many parts

24
Q

Optic ataxis

A

Impaired accuracy in visually guided reaching for an object although accurate when relying on proprioception or auditory guidance with eyes closed

25
Q

Ocular apraxia

A

Impaired/inaccurate voluntary saccades to a target object, especially to peripheral target

26
Q

Nasal visual fields processed by ___ retina

A

Temporal

27
Q

Left visual fields processed by _____ LGN and ____cortex

A

Right

Right

28
Q

Optic radiations: superior

A

Inferior visual field

29
Q

Inferior Optic radiations

A

Superior visual field

30
Q

Superior visual space is processed by ____ retinal and _____ side of cal caring sulcus

A

Inferior

Inferior

31
Q

Peripheral to central visual space makes from the

A

Parietal-occipital sulcus toward the occipital pole

32
Q

Position of LGN in thalamus

A

Inferiorly and laterally

33
Q

Optic radiation course

A

Must initially course anteriorly in order to pass from the medial side of the lateral ventricle to the lateral side of the ventricle. Then they can course posteriorly toward the primary visual cortex

They fan out and from a wide sheet of fibers

34
Q

Pulvinar nucleus of the thalamus

A

Receives some visual input from LGM and superior colliculus

-coordinates oculomotor and visual system

35
Q

LGM damage

A

Can be damaged by a thalamic infarct, either partial or complete unilateral damage. Unilateral infarct including LGN would result in hemianopsia on the opposite side of the LGN

36
Q

Korsakoffs and LGN/pulvinar

A

Not involved in the thalamic neurodegenerative disorders of korsakoffs or Wernickes-Korsakoffs sybdrome

37
Q

What infarcts would affect the optic radiations

A

MCA inferior division occlusion (or branch) or PCA occlusion (small amount)

38
Q

Where are ocular dominance columns

A

Primary visual cortex

39
Q

Circuitry affects in alexia without agraphia

A

Infarct of left primary visual cortex and left splenium; not only induces right homonymous hemianopia, but also blocks projections form intact right visual cortex from crossing midline through splenium to reach left Wernickes area

Loss of reading comprehension using either eye yet intact speech comprehension

40
Q

Circuitry for alexia without agraphia

A

Infarct of left primary visual cortex and left splenium: not only induced right homonymous heminaopia, but also blocks projections from intact right visual cortex from crossing midline through splenium to reach left Wernickes area

Loss of reading comprehnesion using either eye. However intact speech comprehension

41
Q

PTO: non visual functions

A

Processing letters, numbers, calculations

42
Q

Gertsmann syndrome

A

Alexia (impaired comprehension of text), acalculia, RL disorientation

Problem with PTO

43
Q

Dyslexia

A

Developmental disorder of reading. Not understood well

Probably involves PTO region

3P: Neuro (11 decks)

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