Lecture 29

Question 1

What is the double step paradigm?

Answer 1

The time to make a correctino occur within 75 milliseconds

Question 2

What supports the double step paradigm?

Answer 2

The extrageniculate pathway

Question 3

What stimuli is the extrageniculate pathway for?

Answer 3

Dynamic and unexpected stimuli

Question 4

In Zelaznik et al. (1983), what was evaluated?

Answer 4

The minimum time to use vision in an ongiong movement

Question 5

What were the results from Zelaznik et al. (1983)?

Answer 5

Minimum process time to incorporate vision in an ongoing movement is between 75 and 150 milliseconds

Question 6

What is the feedback delay action supported by?

Answer 6

Dorsal visual pathway (V1-PPC)

Question 7

Describe:

Semicircular canals

Answer 7

A part of proprioception - Vestibular system
* 3 fluid filled ‘half circles’
* Can detect changes in the x, y, and z directions

Question 8

What are semicircular canals sensitive for?

Answer 8

Angular accelerations

Question 9

What information do semicircular canals provide?

Answer 9

Provides information regarding position of the head relative to body

Question 10

Describe and give an example of:

Motion detected by the Horizontal (lateral) canal

Answer 10

Detects head rotation around vertical axis (spinning etc.)

Question 11

Describe and give an example of:

Motion detected by the Anterior canal

Answer 11

Detects head rotation in the sagittal plane (nodding etc.)

Question 12

Describe and give an example of:

Motion detected by the Posterior canal

Answer 12

Detects head rotation in frontal planes (completing a somersault etc.)

Question 13

What are the 3 semicircular canals?

Answer 13

1. Horizontal (lateral) canal
2. Anterior canal
3. Posterior canal

Question 14

Describe:

The design of semicircular canals?

Answer 14

Canals filled with fluid and cilia that are orientated in a specific direction

Question 15

What does the cilia do in semicircular canals?

Answer 15

When the movement of the fluid corresponds with the direction of the cilia, it sends a signal to notify the movement

Question 16

Define:

Otolith organs

Answer 16

Detect changes in gravity and acceleration
* A harder structure that the semicircular canals
* Contains utricles and saccules

Question 17

Describe:

Utricle

Answer 17

Detects change in horizontal movement and linear acceleration
* E.x. Walking

Question 18

What is the utricle important for?

Answer 18

Eye movements

Question 19

Describe:

Saccule

Answer 19

Detects changes in vertical movement and linear acceleration
* E.g. Elevation sensation

Question 20

What is the saccule important for?

Answer 20

Posture

Question 21

What is responsible for motion sickness?

Answer 21

The saccule

Question 22

Explain what happens in motion sickness

Answer 22

Sensory mismatch
* Conflict of information between visual and vestibular systems, causing motion sickness

Question 23

What can result from vestibular deficit results?

Answer 23

Lesions involving vestibular nuclei (sending input information) can result in:
* Significant balance deficits
* Shows as a leaning towards one direction, almost falling in that direction

Question 24

True or False:

VOR happens unconsciously

Answer 24

True, vestibular ocular reflex occurs unconsciously

Question 25

# Describe: Vestibular ocular reflex (VOR)

Answer 25

When the head moves in one direction, the VOR will move the eyes back in the opposite direction of head movement

Question 26

What is the purpose of VOR?

Answer 26

To maintain stable fixation on something (e.x. eyes on the road when it is bumpy)

Question 27

What can lesions causing loss of VOR lead to?

Answer 27

Can cause nystagmus eye movement

Question 28

What is nystagmus eye movement?

Answer 28

Rapid eye movement attempting to maintain fixation

Question 29

Why does nystagmus eye movement when you consume alcohol?

Answer 29

Changes viscosity of fluid in semicircular canals, creates perception that you are moving even though you aren't

Question 30

How are muscle spindles connected with extrafusal muscle fibers?

Answer 30

Connect in parallel

Question 31

What do muscle spindles do?

Answer 31

Provide information about stretch of the muscle

Question 32

How is the sensitivity to stretch of a muscle spindle set?

Answer 32

Set by fusimotor/gamma motor neurons

Question 33

# True or False: There is 1 type of muscle spindle

Answer 33

False, there are multiple

Question 34

What types of muscle spindles provide system with information about limb position?

Answer 34

Type 1a and Type 2

Question 35

# Describe: Type 1a muscle spindles

Answer 35

* Sensitive to rapid stretch of the muscle * Active when there is a velocity change induced by a strertch of the muscle

Question 36

When is a type 1a muscle spindle most active?

Answer 36

When you first begin to move (when the agonist first begins contraction)

Question 37

# Describe: Type 2 muscle spindles

Answer 37

* Provide information about static position of the limbs * Provide information about static stretch

Question 38

What does a type 2 muscle spindle allow you to know?

Answer 38

Allows you to know where your limb is when it is not moving

Question 39

# Describe: Monosynaptic stretch reflex

Answer 39

Involves one synapse * E.x. Knee tap reflex

Question 40

# Explain: How the knee tap reflex works

Answer 40

1. Hammer strike on patella tendon causes quadriceps muscles to stretch 2. Detected by type 1a muscle spindles, sends information to spinal cord 3. Information synapses and send DIRECTY to an alpha motor neuron 4. Stretched muscle contracts (ACTIVATES)

Question 41

# Describe: Hyperreflexia

Answer 41

Abnormal, exaggerated reflex * Exaggerated motor neuron amplitude causes abnormally large contract and thus motion

Question 42

What does hyperreflexia indicate?

Answer 42

Indicative of an upper motor neuron injury

Question 43

# Describe: Hyporeflexia

Answer 43

Absence of reflex * Absence on contraction or small contraction

Question 44

What does hyporeflexia indicate?

Answer 44

Indicative of a lower motor neuron injury

Question 45

What are the two postural control strategies?

Answer 45

Ankle strategy Hip strategy

Question 46

When is the ankle strategy used? Describe

Answer 46

When there is a small threat to posture stability * To counteract, body recruits muscles in inverted pendulum strategy

Question 47

When is the hip strategy used? Describe

Answer 47

When there is a major threat to posture stability * Uses a proximal to distal strategy

Question 48

What is the inverted pendulum strategy?

Answer 48

Normally, body goes from proximal to distal * Inverted pendulum is going from distal to proximal

Question 49

# True or False: The hip strategy is more efficient than the ankle strategy

Answer 49

False, it is not very efficient

Question 50

Where are Golgi tendon organs (GTOs) located?

Answer 50

Located in the neuro-tendinous junction between muscle and tendon

Question 51

Why are GTOs hard to study?

Answer 51

Manipulations will rupture them

Question 52

# Describe: Function of Golgi tendon organ

Answer 52

Provide information about tnesion or force development in the muscle * Prevents overstretch and rupture by inhibiting alpha motor neuron

Question 53

What kind of synapse connections do Golgi tendon organs use?

Answer 53

Oligosynaptic (two synapses) connections

Question 54

# Describe: How the Golgi tendon organs and oligosynaptic connections work

Answer 54

1. Sends information to CNS about a contracting muscle 2. Information gets projected into CNS and synapses with an inhibitory interneuron 3. Inhibitor interneuron synapses with alpha motor neuron 4. DEACTIVATES the alpha motor neuron

Question 55

# True or False: Athletes can ignore information from GTO

Answer 55

True