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Neuro Unit 2 > Lec 9 Vision > Flashcards

Lec 9 Vision Flashcards

1
Q

At the chiasm, what % cross? What % continue ipsilaterally?

A

60% cross.
40% ipsi.

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2
Q

Why do only some cross at the chiasm?

A

important for binocular vision & depth perception

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3
Q

Optic Tracts project where? (4)

A 
Lateral Geniculate (thalamus)
Suprachiasmatic Nucleus (hypothal)
Pretectum
Superior Colliculus (midbrain)
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4
Q

Lateral Geniculate projects where?

A

optic radiations, then to primary visual cortex (V1)

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5
Q

primary visual cortex = brodmans area ___

A

17

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6
Q

Ventral pathway of primary visual cortex projects where?

A

temporal lobe

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7
Q

Dorsal pathway of primary visual cortex projects where?

A

parietal lobe

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8
Q

Retino-hypothalamic path functions

A

circadian rhythm
ANS response

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9
Q

Pretectum function

A

pupillary reflex

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10
Q

Pretectum projects where?

A

Edinger-Westphall (midbrain)

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11
Q

Edinger-Westphall PRE-ganglionic projects where?

A

CN 3 -> ciliary ganglion (lens accom)

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12
Q

Edinger-Westphall POST-ganglionic projects where?

A

sphincter pupillary muscle

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13
Q

Superior colliculus function

A

coordinate head/eye movements

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14
Q

Pupillary direct response

A

stimulated eye constricts

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15
Q

Pupillary consensual response

A

contralateral (un-stimulated) eye also contracts

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16
Q

Axons from the Nasal retina ____ in the chiasm (cross/stay on same side)?

A

cross

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17
Q

Axons from the Temporal retina ____ in the chiasm (cross/stay on same side)?

A

stay on same side

18
Q

Left visual field: which nasal retina, which temporal retina, which optic tract?

A
  • *Left** nasal retina
  • *Right** temporal retina
  • *Right** optic tract
19
Q

Right visual field: which nasal retina, which temporal retina, which optic tract?

A
  • *Right** nasal retina
  • *Left** temporal retina
  • *Left** optic tract
20
Q

Meyers loop: where is it, what part of visual field does it view?

A

inferior Lateral Geniculate.
superior visual field.

21
Q

Superior Lateral Geniculate views what part of the visual field?

A

inferior

22
Q

Anopsia vs. Scotoma

A 
Anopsia = large deficit
Scotoma = small deficit
23
Q

Damage at A

A

complete loss of R visual field

24
Q

Damage at B (Chiasm)

A

Bitemporal Hemianopsia
loss of fibers crossing (from both nasal retina) = loss of both temporal fields.

25
Q

Damage at C (Optic Tract)

A

Left Homonymous Hemianopsia.
loss of fibers from R temporal & L nasal = loss of R nasal field + loss of L temporal field

26
Q

Damage at D (Optic Radiations)

A

Superior Homonymous Quadrantopsia.
loss of fibers from R superior temporal & L superior nasal = loss of L temporal + R nasal superior fields

27
Q

Damage at E (Primary Visual Cortex)

A

Homonymous Hemianopsia w/ Macular Sparing
unknown mechanism

28
Q

Role of extraocular musc

A

Foveation: direct fovea towards object of interest

29
Q

Lat/Med Rectus actions

A

horizontal movements (ABD/ADD)

30
Q

Sup/Inf Rectus actions

A

vertical movements (elev/depress)

31
Q

Sup/Inf Oblique actions

A

Intorsion: top of eye toward nose.
Extorsion: top of eye away from nose.

32
Q

Elevation force couple

A

Sup Rectus
Inf Oblique

33
Q

Depression force couple

A

Inf Rectus
Sup Oblique

34
Q

Vestibulo-Ocular Reflex (VOR)

A

when head moves, eyes move the same distance/speed in OPPOSITE direction

35
Q

Why are saccadic movements considered “ballistic”

A

cannot respond to changes in target position once already started. If a target moves during a saccade, a second saccade must be generated.

36
Q

Amplitude of saccades

A

duration of neuron activity (freq of APs)

37
Q

Direction of saccade is governed by

A

2 gaze centers in Reticular Formation

  1. PPRF
  2. Rostral Interstitial Nucleus
38
Q

PPRF = ____ (horizontal/vertical) movements

A

horizontal

39
Q

Rostral Interstitial Nucleus = ____ (horizontal/vertical) movements

A

vertical

40
Q

What happens once PPRF is activated?

A

Activates ipsi Abducens, which activates LMNs (to ipsi Lat Rectus) and Internuclear neurons (to contra Oculomotor = Med Rectus)

41
Q

L PPRF is activated by

A

R frontal eye field
R superior colliculus

Neuro Unit 2 (10 decks)

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