Sensory Component Of Motor Control Flashcards
Types of sensory receptors
Mechanoreceptors
Photoreceptors
Chemoreceptors
Thermoreceptors
Nocioreceptors
What is the neural basis of touch
Skin receptors
Skin receptors
Mechanoreceptors located in the dermis layer of skin
- provide CNS with temp, pain, and movement info
Where are the greatest concentration of skin receptors
Finger tips
How was impact of touch during movement tested
Comparing performance of task before and after anesthitizing
What is impact of touch during movement
- Improves movement accuracy
- Improves movement consistency
- Enables force adjustments during movement
- Improves distance estimation during pointing
Haptic input
Combination of cutaneous and proprioceptive info
What can haptic input compensate for
Deficiencies in other sensory systems
Example of Haptic Touch and balance control
Light touch improves balance control in people with balance impairments
Proprioception
Perception of limb, body, and head movement characteristics
- where body segments are in relation to the body
What does proprioception provide
Afferent sensory info regarding direction, location and velocity of movement
Where does CNS receive proprioception info
Afferent neural pathways that begin in specialized sensory neurons known as proprioceptors
Where are proprioceptors located
Muscles, tendons, ligaments and joints
3 types of proprioceptors
- Muscle spindles (detect stretch)
- Golgi tendon organs (detect tension/force)
- Joint receptors (detect compression)
Most important source of proprioceptive info
Muscle spindles
What info do muscle spindles provide about body
Position
Direction
Velocity
Sense of effort
What are muscle spindles
Sensory receptors and gamma intrafusal muscle fibers
How do muscle spindle sensory receptors work
Type 1a sensory nerves carry signals from muscle spindles
Detect changes in length and velocity of stretch
Mechanical deformation stimulates nerve impulse
What are nerve impulses of muscle spindles
Shortening = decrease frequency
Lengthening = increase frequency
1a sensory nerves connect to/synapse with
- Alpha-motor neurons of agonist muscle
- Inhibitory interneurons of antagonist muscles
- Alpha-motor neurons of synergistic muscles
- Interneuron in brainstem and spinal cord
What doses 1a connecting to alpha motor neurons of agonist cause
Monosynaptic stretch reflex
What does 1a connecting with inhibitory interneurons of antagonist muscles cause
Prevents firing of antagonist muscles
What does 1a connecting to alpha motor neurons of synergistic muscles cause
- weak monosynaptic connections
- help with intended movement
What does 1a connecting to interneurons in brainstem and spinal cord cause
Continued ascent for higher level control
How are muscle spindles kept at desired lengths
Intrafusal fibers lie in parallel with extrafusal fibers to keep spindle at desired lengths
What controls intrafusal fibres of muscle spindles
Gamma motor neurons
What 3 things do gamma motor neurons do to control intrafusal fibres of muscle spindles
- Set desired muscle spindle length
- Control and maintains sensitivity of 1a receptors
- Prevent spindle from becoming unloaded during concentric contractions
What is creep
Muscles stretched for long period of time and muscle spindles stop working
Where are Golgi tendon organs located
In musculo-tendon junction (in skeletal muscle near insertion of tendon)
What are GTOs
1b sensory nerves
Detect changes in muscle tension/force (causes relaxation)
Where are joint receptors found
Joint capsule and ligaments
3 types of joint receptors
Ruffini endings
Pacinian corpuscles
Golgi-like receptors
What do not all joint receptors have in common
Not same type and number of receptors
What are joint receptors
Mechanoreceptors that detect changes in
- force and rotation applied to joint
- joint movement angle, especially at extreme limits of angular movement or joint positions
2 techniques to investigate role of proprioception in motor control
- deafferentation techniques
- tendon vibration techniques
Deafferentation techniques
Proprioceptive feedback removed
Tendon vibration techniques
- high speed vibration of the tendon of the agonist muscle
- proprioceptive feedback is distorted
What is deafferentation
Removal (temporary or permanent) of sensory info
What does deafferentation provide
Info about what movements can be accomplished without afferent info
3 types of deafferentation
- 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)
Effects of surgical deafferentation
- 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)
injury and proprioception
- actions are too quick for feedback in proprioceptors to cause adjustment
- wrong execution happens too quickly
How can injury affect proprioception
Lost sensitivity in muscle spindles so can’t detect when its going to happen again
Proprioception after injury
- soft tissue injury results in disruption to afferent-efferent neuromuscular control arc
- extremely important to train proprioception after injury to prevent re-injury
Examples of proprioception training
- BOSU
- balance rocks
- body bar
- Pilates ball
- foam
-perturbations
