24-Motor5-Eye Flashcards

1
Q

ballistic movement

A

once initiated, cannot be modified

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2
Q

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

A

2,2

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3
Q

Why are saccades necessary?

A
  • 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
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4
Q

Approximate duration of saccades

A

20-50 ms

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5
Q

Peak velocity scales with saccade ___

A

amplitude

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6
Q
A

true

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7
Q

Chain of descending saccade control (x5)

A
  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)
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8
Q
A

false

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9
Q

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

A

Brainstem saccade generator

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10
Q

Cranial nerves involved in saccade output

A
  • abducens
  • oculomotor
  • trochlear
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11
Q

Eye muscles of horizontal movement

A

medial and lateral rectus

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12
Q

Eye muscles of vertical movement

A

superior and inferior rectus

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13
Q

Superior rectus activation leads to ___ of eye

A

elevation

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14
Q

Inferior rectus activation leads to ___ of eye

A

depression

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15
Q

Medial rectus activation leads to ___ of eye

A

adduction

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16
Q

Lateral rectus activation leads to ___ of eye

A

abduction

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17
Q

Motor nucleus of superior rectus

A

oculomotor

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18
Q

Motor nucleus of medial rectus

A

oculomotor

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19
Q

Motor nucleus of inferior rectus

A

oculomotor

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20
Q

Motor nucleus of lateral rectus

A

abducens

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21
Q

Regions in cortical eye fields (x3)

A
  • frontal eye fields (FEF)
  • lateral intraparietal (LIP)
  • supplementary eye fields (SEF)
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22
Q

FEF

A

frontal eye fields

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23
Q

LIP

A

lateral intraparietal (aka posterior parietal cortex)

24
Q

SEF

A

supplementary eye fields

25
Q

Regions involved in saccade control within brainstem (x3)

A
  • saccade pattern generators
  • pontine reticular formation (horiz comp)
  • mesencephalic reticular formation (vert comp)
26
Q

PPRF

A

(paramedian) pontine reticular formation

27
Q

Pontine reticular formation is involved in

A

horizontal saccade component

28
Q

riMLF

A

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

29
Q

Mesencephalic reticular formation is involved in

A

vertical saccade component

30
Q
A

false, lesion in both is required for complete abolishment

31
Q

FEF neurons are spatially tuned for saccade ___ and ___

A

direction, amplitude

32
Q

Preferred saccade of FEF neuron, definition

A

saccade associated with maximum activity of a single FEF neuron

33
Q

Movement field of FEF neuron, definition

A

range of saccades for which single FEF neuron is active

34
Q

[Inferior/superior] colliculus is involved in saccade control

A

superior

35
Q

deep layers of superior colliculus are involved in

A

saccade control

36
Q

superficial layers of superior colliculus are involved in

A

visual processing

37
Q
A

true

38
Q
A

true

39
Q

Rightward saccade:
Which regions of control are on left side vs. right side of brain?

A

Right (ipsilateral-ish):
- PPRF
- abducens nucleus
- lateral rectus activation
Left (contralateral-ish):
- cortical eye fields
- superior colliculus
- oculomotor nucleus
- medial rectus activation

40
Q

Upward saccade:
What regions are involved?

A
  • Cortical eye fields
  • Superior colliculus
  • riMLF
  • Oculomotor nucleus
  • superior/inferior rectus
41
Q

Two components of saccade

A

pulse and step

42
Q

Types of neurons involved in saccade generation

A
  • burst neurons (drive pulse of saccade)
  • tonic neurons (neural integrator, control eye position)
  • omnipause neurons (high firing rate, suppresed for every saccade, located in dorsal raphe)
43
Q

Location of omnipause neurons

A

dorsal raphe nucleus

44
Q

Role of substantia nigra (pars reticulata) in saccades

A

GABAergic, projects to superior colliculus, tonically inhibits saccades (gating function)

45
Q

Role of caudate nucleus in saccades

A

Excited by cortical input, project to substantia nigra (pars reticulata), GABAergic, causes a pause in nigra firing

46
Q

Purpose of smooth pursuit

A

to track moving visual target

47
Q
A

true

48
Q
A

false

49
Q

Tracking of an imagined object involves [smooth pursuit / saccades]

A

saccades only

50
Q

Tracking of own finger in dark involves [smooth pursit / saccades]

A

combination of both? Definitely smoother than tracking imagined object, but not as smooth as tracking visible object

51
Q

Chain of descending smooth pursuit control (x5)

A
  1. cerebral cortex (voluntary smooth pursuit command)
  2. pontine nuclei (relay into cerebellum)
  3. Cerebellar flocculus (area of cerebullum that is required for smooth pursuit)
  4. Vestibular nuclei (output to motor nuclei for eye muscles)
  5. Abducens/oculomotor nuclei
52
Q

Areas of cortex involved in SmPu motor commands (x2)

A

FEF and SEF

53
Q
A

true

54
Q

Cerebellar ___ is involved in saccades

A

vermis

55
Q

Cerebellar ___ is involved in smooth pursuit

A

flocculus