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BIOL21332 - Motor Systems > Lecture 18 - Vestibular influences on occulomotor control and posture > Flashcards

Lecture 18 - Vestibular influences on occulomotor control and posture Flashcards

1
Q

Where does the output of the vestibular labyrinths project to?

A

The vestibular nuclei

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2
Q

What is the role for vestibulo-ocular reflexes?

A

To keep images on the eyes still when the head moves

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3
Q

What is the role for the vestibulospinal relfexes?

A

To enable the skeletomotor system to compensate for head movements

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4
Q

What signals how fast the head is rotating?

A

The vestibular apparatus

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5
Q

The occulomotor system uses information from the vestibular apparatus to do what?

A

Stabilise the eyes to keep images in the retina

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6
Q

What are the three different types of VOR? [3]

A
  • Rotational vestibular-ocular reflex
  • Translational vestibular-ocular reflex
  • Ocular counter-rolling response
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7
Q

What does Rotational vestibular-ocular reflexes compensate for?

A
  • Head rotation

- Recieves inputs from the semicircular canals

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8
Q

What does the Translational vestibular-ocular reflex compensate for?

A

Linear head movements

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9
Q

What does the Ocular counter-rolling response compensate for?

A

Head tilt in the vertical plane

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10
Q

How does the rotational vestibular-ocular reflex control the eyes?

A

They cause them to slowly rotate in the opposite direction to any rotational head movement

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11
Q

The coordination of head and eye movements to direct the fovea is called?

A

Gaze

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12
Q

What do small gaze movements cause?

A

Saccades

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13
Q

What happens when gaze movements are larger?

A
  • Head and eyes move simultaneously

- VOR is supressed

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14
Q

What are two problems with the VOR?

A
  • It habituates

- The canals do not response well to very slow head movements

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15
Q

How can the problems with the VOR be componsated for?

A

The optokinetic system provides the central vestibular system with visual information

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16
Q

What properties are shared between the VOR and the optokinetic reflex?

A
  • Builds up slowly

- Responds to very slow visual image motion

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17
Q

What is circular vection?

A

When the whole scene is moving it messes up the vestibular stabilisation

18
Q

What does vestibular stabilsation do?

A

Allows one to tell which items are moving and which are stationary

19
Q

Vestibular nuceli respond identically to what?

A
  • Head mvoements

- Movement of an image on the retina

20
Q

How do we know we are falling?

A
  • Visual

- The head moves

21
Q

What is the major factor in the maintainance of posture?

A

Signals from the vestibular nuceli to the spinal cord

22
Q

What are the four different vestibular nuclei? [4]

A
  • Medial
  • Lateral
  • Superior
  • Descending
23
Q

Where does the superior and medial nuclei recieve inputs from?

A

The semicircular canals

24
Q

Where do the superior and medial nuclei send outputs to?

A
  • Occulomotor centres

- Spinal cord

25
Q

The nuerons on the medial nuclei are?

A

Excitatory

26
Q

The neurons in the superior nuclei are?

A

Inhibitory

27
Q

What are the superior and medial nuclei responsible for?

A

Reflexes that control gaze

28
Q

Where does the lateral nucleus recieve inputs from?

A
  • Semicircular canals

- Otolith organs

29
Q

Where does the lateral nucleus send ouputs to?

A

Lateral vestibularspinal tract

30
Q

What is the lateral nucleus responsible for?

A

Postural reflexes

31
Q

Where does the descending nucleus recieve inputs from?

A

Otolith organs

32
Q

Where does the descending nucleus send ouputs to?

A
  • Cerebellum
  • Reticular formation
  • Contralateral vestibular nuclei
  • Spinal cord
33
Q

What is the descedning nucleus responsible for?

A

Intergrating vestibular signals and central motor signals

34
Q

What does posture refer to?

A

The relative postiiton of the body parts of the body with respect to one another and the environment

35
Q

What is static equilibrium?

A

When all the forces acting on the body are balanced so the body is at rest

36
Q

What is dynamic equilibrium?

A

Intended movement without losing balance

37
Q

What is the main force our body must oppose?

A

Gravity

38
Q

How does an individual remain balanced after moving one leg and standing on the other?

A

A counterbalancing movement that shifts the centre of gravity over to the other leg must be done

39
Q

What does anticipatory response for postrual control depend on?

A
  • Feedforward control

- Adjustments to unexpected disturbances uses feedback control

40
Q

What suggest that the cerebellum is important for motor learning?

A

Patients with cerebellar lesions were unable to make adaptive changes in postural control

41
Q

What organ plays an important role in balance when walking?

A

Vestibular labryinth

BIOL21332 - Motor Systems (21 decks)

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