Motor Control Part 1 Theories of Motor Control Flashcards
What is the Reflex Theory?
A theory of motor control saying that complex behavior could be explained through the combined action of individual reflexes that were “chained” together (stimulus → reflex → stimulus → reflex, etc.)
What are some limitations of the Reflex Theory? (5)
- If both spontaneous and voluntary movements are recognized as behavior then reflex alone cannot be the basic unit of behavior
- Does not explain movements that happen too quickly to allow for sensory feedback from preceding movement to trigger the next
- Does not explain movement that occurs without sensory stimulus (voluntary movement can occur by thought alone)
- Does not explain how a single stimulus can result in varying responses depending on the context and descending commands (many ways to accomplish same goal)
- Does not account for “novel” experiences
What is the Hierarchical Theory?
The brain has higher, middle, and lower levels of control
• Higher = association areas of cortex
• Middle = motor cortex
• Lower = spinal levels of motor function
True or False: There is never bottom up control
True
True or False: In the hierarchical theory, reflexes are not the sole determinant of motor control, but can be part of it.
True
Motor Programming Theories are moving away from what in terms of the CNS?
Moving away from CNS as only a reactive system to it being also an active system.
When we stand upright, activity _________ in ________ postural muscles to counteract the force of gravity.
Increases; antigravity
This definition is: Postural Tone
What type of input is critical for postural tone? (2)
Sensory –> somatosensory and vestibular especially.
Quiet stance is characterized by what 4 things?
- Body alignment/sway
- Postural tone
- Mm tone
- Passive skeletal alignment
Depending on the frequency of sway movement, what two strategies might one use to keep upright?
Ankle or hip strategies
Perturbation is defined as:
A cause of disturbance or upset.
A secondary influence on a system that modifies behavior.
Which movement strategy is most common; A/P or M/L?
A/P
Which part of the CNS selects the specific movement patterns used to recover stability following displacement of the COM?
The higher level cortex.
True or False: Muscles cannot belong to more than one synergy.
False.
What is the ankle strategy?
A postural strategy that keeps the body upright. First the gastrocnemius is activated to keep the body from falling fwd, then the hamstrings, then the paraspinal mm.
What is the hip strategy?
A postural strategy that keeps the body upright. It comes in after the ankle strategy. It is a large, rapid motion at the hips and comes in response to larger and faster perturbations.
When do we use a stepping strategy?
When ankle or hip strategies are not enough.
What senses contribute to postural control? (3)
Vestibular
Visual
Somatosensory
What do each of the three senses contribute in respect to postural control?
Vestibular: Position of head in respect to gravity and inertial forces.
Visual: Position of head in respect to vertical.
Somatosensory: Position of body and its segments in respect to its supporting surfaces as well as each body segment with another.
Quiet stance is characterized by:
small amounts of spontaneous postural sway
What sensory strategies are used in quiet stance? (2)
Visual
Somatosensory
(we don’t use vestibular b/c we’re not moving)
What sensory strategies are used in perturbed stance? (2)
Somatosensory
Vestibular
The Intermodal Theory of Sensory Organization states:
All 3 senses contribute equally to postural orientation at all times.
The Sensory Weighting Hypothesis states:
The postural control system is able to reweight sensory inputs in order to optimize stance in altered sensory environments.
Predicts that each sense provides a unique contribution to postural control.
The CNS has to resolve sensory conflicts by changing the relative weight of a sensory input to postural control.
