Week 4 (MC) - Balance and Vision

Question 1

What are the 2 major functions of the Vestibular Apparatus?

Answer 1

Informs:
1. Which way is up - head relative to gravity
2. Where am i going? - Head in space –> moving or not –> tries to determine whether we are moving or the surrounding environment is moving

Question 2

Difference between semi-circular canals AND Utricle and Saccule?

i.e. what do they detect?

Answer 2

Semi-circular canals
- Detect angular acceleration in any axis
- Head roll, nodding etc.

Utricle and Saccule
- Detect Linear Acceleration in any axis
- Changes in body translation (e.g. forward back, side to side etc)

Question 3

How is movement translated to a neural signal?

This is a hard question lmao - need to know vestibular anatomy

Answer 3

When the head is set in motion, the cupula moves through endolymph fluid that does not initially move due to inertia, causing the cupula to sway or bend.
Physical strain (bending) of capula stimulates neural signal

Question 4

Define the difference between Utricle and Saccules?

Answer 4

Utricles
Provides information about the magnitude of acceleration in the HORIZONTAL PLANE

Saccules
Provides information about VERTICAL accelerations
- Think S for Straight (keeping your head straight) and going up and down

Question 5

What is the important role of the vestibular system?

Answer 5

To stabilise the head and eyes in space (we try to keep our head still during dynamic exercise)

It has a close connection with visual systems

Question 6

What is Gaze?

Answer 6

Is where the eyes are pointing in space
Is a sum of the head position and eye position (when the body is stationary)

Question 7

What is Vestibulo-ocular Reflexes (VOR)?

Answer 7

Reflex eye movements stabilising retinal images in the eye during head movement. Produces eye movement in the direction opposite to head movement, thus preserving the image in centre of visual field.

Question 8

What are the 3 different vestibulo-ocular reflexes (VOR)?

Answer 8

1. Rotational VOR
Compensates for passive/imposed head rotation
Recieves predominant input from horizontal semicircular canals (e.g. Head turn)

2. Ocular Counter-rolling Response
Compensates for HEAD TILT in vertical plane (posterior canal)
- e.g. head bobbing up and down in a boat

3. Translational VOR
Compensats for linear physical movement
Input from Utricle and Saccule
Eyes fix during physical bodily movements

Question 9

What time is unreasonable to use vision to adjust movement?

Answer 9

<160ms cant use vision to adjust to the movement.

Question 10

What is the principle of rate expansion? (Time to contact)

Answer 10

Is showing that the rate of expansion of a visual image on the retina is correlated with the speed or velocity of the approaching object (e.g. cricket ball)

We visualise the amount of space the object takes up in our vision

Question 11

What happens to the rate of expansion when an object moves across your eye?

Answer 11

The percentage of retinal space that the object takes up doesnt change