Sensory Component Of Motor Control

Question 1

Types of sensory receptors

Answer 1

Mechanoreceptors
Photoreceptors
Chemoreceptors
Thermoreceptors
Nocioreceptors

Question 2

What is the neural basis of touch

Answer 2

Skin receptors

Question 3

Skin receptors

Answer 3

Mechanoreceptors located in the dermis layer of skin
- provide CNS with temp, pain, and movement info

Question 4

Where are the greatest concentration of skin receptors

Answer 4

Finger tips

Question 5

How was impact of touch during movement tested

Answer 5

Comparing performance of task before and after anesthitizing

Question 6

What is impact of touch during movement

Answer 6

1. Improves movement accuracy
2. Improves movement consistency
3. Enables force adjustments during movement
4. Improves distance estimation during pointing

Question 7

Haptic input

Answer 7

Combination of cutaneous and proprioceptive info

Question 8

What can haptic input compensate for

Answer 8

Deficiencies in other sensory systems

Question 9

Example of Haptic Touch and balance control

Answer 9

Light touch improves balance control in people with balance impairments

Question 10

Proprioception

Answer 10

Perception of limb, body, and head movement characteristics
- where body segments are in relation to the body

Question 11

What does proprioception provide

Answer 11

Afferent sensory info regarding direction, location and velocity of movement

Question 12

Where does CNS receive proprioception info

Answer 12

Afferent neural pathways that begin in specialized sensory neurons known as proprioceptors

Question 13

Where are proprioceptors located

Answer 13

Muscles, tendons, ligaments and joints

Question 14

3 types of proprioceptors

Answer 14

1. Muscle spindles (detect stretch)
2. Golgi tendon organs (detect tension/force)
3. Joint receptors (detect compression)

Question 15

Most important source of proprioceptive info

Answer 15

Muscle spindles

Question 16

What info do muscle spindles provide about body

Answer 16

Position
Direction
Velocity
Sense of effort

Question 17

What are muscle spindles

Answer 17

Sensory receptors and gamma intrafusal muscle fibers

Question 18

How do muscle spindle sensory receptors work

Answer 18

Type 1a sensory nerves carry signals from muscle spindles
Detect changes in length and velocity of stretch
Mechanical deformation stimulates nerve impulse

Question 19

What are nerve impulses of muscle spindles

Answer 19

Shortening = decrease frequency
Lengthening = increase frequency

Question 20

1a sensory nerves connect to/synapse with

Answer 20

1. Alpha-motor neurons of agonist muscle
2. Inhibitory interneurons of antagonist muscles
3. Alpha-motor neurons of synergistic muscles
4. Interneuron in brainstem and spinal cord

Question 21

What doses 1a connecting to alpha motor neurons of agonist cause

Answer 21

Monosynaptic stretch reflex

Question 22

What does 1a connecting with inhibitory interneurons of antagonist muscles cause

Answer 22

Prevents firing of antagonist muscles

Question 23

What does 1a connecting to alpha motor neurons of synergistic muscles cause

Answer 23

• weak monosynaptic connections
• help with intended movement

Question 24

What does 1a connecting to interneurons in brainstem and spinal cord cause

Answer 24

Continued ascent for higher level control

Question 25

How are muscle spindles kept at desired lengths

Answer 25

Intrafusal fibers lie in parallel with extrafusal fibers to keep spindle at desired lengths

Question 26

What controls intrafusal fibres of muscle spindles

Answer 26

Gamma motor neurons

Question 27

What 3 things do gamma motor neurons do to control intrafusal fibres of muscle spindles

Answer 27

1. Set desired muscle spindle length 2. Control and maintains sensitivity of 1a receptors 3. Prevent spindle from becoming unloaded during concentric contractions

Question 28

What is creep

Answer 28

Muscles stretched for long period of time and muscle spindles stop working

Question 29

Where are Golgi tendon organs located

Answer 29

In musculo-tendon junction (in skeletal muscle near insertion of tendon)

Question 30

What are GTOs

Answer 30

1b sensory nerves Detect changes in muscle tension/force (causes relaxation)

Question 31

Where are joint receptors found

Answer 31

Joint capsule and ligaments

Question 32

3 types of joint receptors

Answer 32

Ruffini endings Pacinian corpuscles Golgi-like receptors

Question 33

What do not all joint receptors have in common

Answer 33

Not same type and number of receptors

Question 34

What are joint receptors

Answer 34

Mechanoreceptors that detect changes in - force and rotation applied to joint - joint movement angle, especially at extreme limits of angular movement or joint positions

Question 35

2 techniques to investigate role of proprioception in motor control

Answer 35

- deafferentation techniques - tendon vibration techniques

Question 36

Deafferentation techniques

Answer 36

Proprioceptive feedback removed

Question 37

Tendon vibration techniques

Answer 37

- high speed vibration of the tendon of the agonist muscle - proprioceptive feedback is distorted

Question 38

What is deafferentation

Answer 38

Removal (temporary or permanent) of sensory info

Question 39

What does deafferentation provide

Answer 39

Info about what movements can be accomplished without afferent info

Question 40

3 types of deafferentation

Answer 40

- surgical (afferent neural pathways surgically removed or altered) - due to sensory neuropathy (large myelinated fibres of limb are lost) - temporary (nerve block - inflate BP cuff to create temp disuse)

Question 41

Effects of surgical deafferentation

Answer 41

- decreased movement precision during activities of daily living or newly learned movements (monkeys) - altered locomotor patterns (cats) - postural responses to surface rotations are altered following total knee replacement (humans)

Question 42

injury and proprioception

Answer 42

- actions are too quick for feedback in proprioceptors to cause adjustment - wrong execution happens too quickly

Question 43

How can injury affect proprioception

Answer 43

Lost sensitivity in muscle spindles so can’t detect when its going to happen again

Question 44

Proprioception after injury

Answer 44

- soft tissue injury results in disruption to afferent-efferent neuromuscular control arc - extremely important to train proprioception after injury to prevent re-injury

Question 45

Examples of proprioception training

Answer 45

- BOSU - balance rocks - body bar - Pilates ball - foam -perturbations