VOR

Question 1

Stabilizes retinal image during head motion

Answer 1

VOR

Question 2

VOR generates eye movements that are

Answer 2

Same speed as head motion but opposite direction to keep the target on the fovea

Question 3

If you move a book in front of your eyes the words will be

Answer 3

Blurry. Because of no VOR. Visual info takes 100ms to get to motoneurons

Question 4

If you keep a book stable but move your head the words will be

Answer 4

Clear - VOR active. Vestibular info takes 7-15 ms to get to motoneurons

Question 5

Visual into compared to vestibular info

Answer 5

Visual info takes longer than VOR

Question 6

Since the VOR driver is vestibular and not visual

Answer 6

It is operational in the dark! Unlike visual info

Question 7

Change in position from side to side , up and down, or for and aft

Answer 7

Translation

Linear acceleration

Question 8

Change in orientation, left to right, tilt up and down, roll shoulder to shoulder is

Answer 8

Rotational

Angular acceleration

Question 9

What is the key difference in static and dynamic

Answer 9

Dynamic gets eyes there, while static keeps them there

Question 10

Compensate for the head remaining still in single tilted or turned position

Answer 10

Static

Question 11

Compensates for the active process of tilting or rotating the head -> accelerated change

Answer 11

Dynamic

Question 12

Both: static and dynamic

Answer 12

Change the eye’s positions as the head position is changed

Question 13

What is the net result of static and dynamic responses?

Answer 13

Eye pointing to the same place in space as before the movement

Question 14

The goal of an effective VOR eye movement is to

Answer 14

Compensate for head movement (math the velocity)

Question 15

Gain is the eye/head velocity. Which is ideally

Answer 15

-1.0

Question 16

Phase is the temporal difference which is ideally

Answer 16

180 degrees

Question 17

Normal values for horizontal and vertical VOR in the dark

Answer 17

In the dark the VOR gain is -0.9 and phase shift is 0

Worse

Question 18

Normal values for horizontal and vertical VOR in light

Answer 18

VOR gain is -1.0 and phase shift is 0.

Light may be helped with visual input and OKN

Question 19

VOR is mainly from ___.

Answer 19

Anterior and posterior canals

Question 20

Static torsional VOR is mediated by

Answer 20

Otolith (not canals)

Question 21

If gain is too high/low and there is a phase lead/lag they will cause

Answer 21

Blur and oscillopsia (imbalance )

Question 22

Ig gain is too high/low there will be

Answer 22

Transient stability of the retinal image

Question 23

If phase lead or phase lag there will be

Answer 23

Constant instability of the retinal image

Question 24

Peripheral (labyrinth) lesions cause

Answer 24

Static (nystagmus) and dynamic (abnormal gain/pahse) imbalance

Question 25

Would it be better to have a shorter or longer time contact (quantifying VOR)

Answer 25

It would be better to have a long time constant because it means you’re accomplishing the task with more time

Question 26

What is the time constant? | What is the normal?

Answer 26

Time it takes for the GAIN to decrease to 37% of its original value (Normal; 12-15 second)

Question 27

What cab decrease time constant (Tc)

Answer 27

``` Repeated test Newborns (have lower than adults) Amblyopia Diseases ANYTHING THAT DECREASES TC IS BAD FOR YOU ```

Question 28

Time constant is when 37% of peak v occurs. You don’t want. To leave peak so quickly meaning

Answer 28

You don't want a shorter Tc

Question 29

Otolith organs

Answer 29

Utricle and succulent

Question 30

Otoliths contain ____ and ____.

Answer 30

Crystals attached to gelatin And Hair cells (sterocilia and kinocilia)

Question 31

When there’s a bend towards kinocilia

Answer 31

Depolarization occurs

Question 32

Sterocilia and kinocilia are embedded in layer and bend when

Answer 32

Crystals are displaced

Question 33

Utricle detects

Answer 33

Horizontal acceleration

Question 34

Saccule detects

Answer 34

Vertical acceleration

Question 35

Inertia of the otoconia with head movements causes dereliction of the stereocilia and A

Answer 35

Subsequent stimulatory or inhibitory response in sensory nerve fibers within CN

Question 36

When stereocilia bend away from kinocilium

Answer 36

Hyper polarized vestibular nerve (inhibition)

Question 37

When stereocilia bend toward kinocilium

Answer 37

AP in vestibular nerve (excitation/depolarization)

Question 38

If head is tilted right, ___ activated and ___ inhibited. | Resulting in + to___ and - to ___. IPSILATERAL INTORTION

Answer 38

R med utricle activated R lat utricle inhibited + RSO -RIO IPSILATERAL INTORTION

Question 39

What can go wrong with otoliths?

Answer 39

Skew deviation: vertical strabismus cause by supranuclear brainstem or cerebellar lesion. It has been associated with asymmetric otolith ocular inputs