24-Motor5-Eye Flashcards Preview

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Flashcards in 24-Motor5-Eye Deck (55)
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1

ballistic movement

once initiated, cannot be modified

2

Fovea is ___ mm wide on retina, covers about ___ degrees of central vision

2,2

3

Why are saccades necessary?

- Have to reposition fovea to sample important parts of image
- But eye needs to be stationary to resolve clear image
- Therefore saccades move as quickly as possible then freeze

4

Approximate duration of saccades

20-50 ms

5

Peak velocity scales with saccade ___

amplitude

6

[True/false]: voluntary saccades can be made on verbal command without a visual target

true

7

Chain of descending saccade control (x5)

1. Cerebral cortex (voluntary saccade command of direction and amplitude)
2. Superior colliculus (reflexive saccades, head movements)
3. Brainstem saccade generator (computes commands for individual muscles)
4. Motor neurons (abducens, oculomotor, trochlear nuclei)
5. Eye muscles (horiz: medial,lateral rectus; vert: superior, inferior retus)

8

[True/false]: cortex encodes signals for specific muscles in saccade control

false

9

Site of translation from abstract saccade direction/amplitude to individual muscle signals

Brainstem saccade generator

10

Cranial nerves involved in saccade output

- abducens
- oculomotor
- trochlear

11

Eye muscles of horizontal movement

medial and lateral rectus

12

Eye muscles of vertical movement

superior and inferior rectus

13

Superior rectus activation leads to ___ of eye

elevation

14

Inferior rectus activation leads to ___ of eye

depression

15

Medial rectus activation leads to ___ of eye

adduction

16

Lateral rectus activation leads to ___ of eye

abduction

17

Motor nucleus of superior rectus

oculomotor

18

Motor nucleus of medial rectus

oculomotor

19

Motor nucleus of inferior rectus

oculomotor

20

Motor nucleus of lateral rectus

abducens

21

Regions in cortical eye fields (x3)

- frontal eye fields (FEF)
- lateral intraparietal (LIP)
- supplementary eye fields (SEF)

22

FEF

frontal eye fields

23

LIP

lateral intraparietal (aka posterior parietal cortex)

24

SEF

supplementary eye fields

25

Regions involved in saccade control within brainstem (x3)

- saccade pattern generators
- pontine reticular formation (horiz comp)
- mesencephalic reticular formation (vert comp)

26

PPRF

(paramedian) pontine reticular formation

27

Pontine reticular formation is involved in

horizontal saccade component

28

riMLF

mesencephalic reticular formation (aka rostral interstitial nucleus of the medial longitudinal fasciculus)

29

Mesencephalic reticular formation is involved in

vertical saccade component

30

[True/false]: A lesion in either the FEF or SC will abolish saccades

false, lesion in both is required for complete abolishment