Week 13 Flashcards
What are the 3 motor control theories?
- Reflex theories
- Historical theories (motor program theory)
- Dynamical/Ecological theories
(dynamical systems theory)
Whose work is the reflex theory based off of?
Sir Charles Sherrington
What are 2 basic assumptions of the reflex theory?
- reflexes are fundamental building blocks of all movement
* events in EN served as stimulus for action
In the reflex theory, complex behaviors result from?
chaining of reflexes
• individual is a passive recipient of externally-produced sensory input that excites motor systems
In the reflex theory: sensory –> _______–> ____________
sensory –> motor –> sensory (feedback)
monkey unilateral UE deafferentation (DRG cut) - lost mvmt. / went unchallenged for over 60 years
Is the reflex theory closed or open looped?
closed-loop in nature
List some of the reflex theories limitations:
Can’t explain:
- spontanteous or voluntary movements
- fast sequential movements (e.g. typing)
- reflexes can be modulated
- a single stimulus can trigger various responses - novel movements can be carried out
- Taub (1980) - deafferented monkeys
In contrast to the reflex theory, hierarchical theory assumes that all aspects of movement planning and execution are:
responsibility of one or more cortical centers representing highest command level within CNS
Is the hierarchical theory top-down or bottom-up?
top-down
In the hierarchical theory, motor control emerges from reflexes nested within:
hierarchically organized level in CNS
In the hierarchical theory:
• Higher centers always in control of ____________________.
• higher centers inhibit _________________________.
• Reflexes control by lower centers dominate movement only when _________________________.
- Higher centers always in control of LOWER CENTERS.
- higher centers inhibit REFLEXES CONTROLLED BY LOWER BRAIN CENTERS.
- Reflexes control by lower centers dominate movement only when HIGHER CENTERS ARE DAMAGED.
(Hierarchal theory) Neuromaturational theory of development, brain determines ________ behavior
infant
In the hierarchal theory, the cortex controls the postural reflex development of ___________________ and motor development of __________________.
In the hierarchal theory, the cortex controls the postural reflex development of EQUILIBRIUM REACTIONS and motor development of BIPEDAL FUNCTION.
In the hierarchal theory, the midbrain controls the postural reflex development of ___________________ and motor development of __________________.
In the hierarchal theory, the midbrain controls the postural reflex development of RIGHTING REACTIONS and motor development of QUADRUPEDAL FUNCTION.
In the hierarchal theory, the brainstem / spinal cord controls the postural reflex development of ___________________ and motor development of __________________.
In the hierarchal theory, the brainstem / spinal cord controls the postural reflex development of PRIMATIVE REFLEX and motor development of APEDAL FUNCTION.
List the limitations of the Hierarchical theory:
- can’t explain dominance of reflex behavior in certain adult situations (flexor withdrawl)
- EN and other non-CNS factors can affect infant movement (infant stepping reflex)
What are the current opinions on the hierarchical models?
- each level of motor system can act on other levels
* reflexes are only one of many motor control processes
Influence of Hierarchical theory on treatment paradigms: “When the influence of higher centers is temporarily or permanently interfered with, _______________________________________.”
normal reflexes become exaggerated and so called pathological reflexes appear
Influence of Hierarchical theory on treatment paradigms: “The release of motor responses integrated at lower level from restraining, influences of higher center, especially that of the cortex, leads to _____________________________.”
abnormal postural reflex activity
Motor program theory (hierarchical) =
detailed instructions are specified by the CNS to carry out the entire movement.
What are 2 key features of the motor program theory (hierarchical)
- Existence of Generalized Motor Programs
2. Existence of motor memory Schemas
What does the generalized motor program do?
organize, initiates, and carries out intended actions
(Motor program theory) proposed that every movement does not require:
a seperate motor program (command from executive is more general)
(motor program theory) introduced the concept of _____________________.
generalized motor program
The generalized motor programs (GMPs) represent a pattern of movement (or class of actions) that can be modified to:
modified to yield various response outcomes
For GMPs, elements of the GMP that are fixed from trial to trial =
invariants
For GMPs, elements of the GMP that are flexible =
parameters
Invariant features of GMP =
fixed features are similar to fingerprints (can identify particular motor program)
Invariant features of GMP are a unique set of characteristics that define a specific GMP and do not vary from:
one performance to another
List a few common examples of Invariant features of GMPs:
- sequence of actions
- relative timing
- relative force used
Name two examples of sequence of actions:
- spelling of name
2. spiking a volleyball
Name an example for the invariant feature of relative force of muscle output:
ratio of muscle output relative to others
Name 2 examples for the invariant feature of relative timing:
- proportion (%) of total amount of time required by each component of a skill during the performance of skill
- analogous to adjusting a recipe to yield more servings (proportion of ingredients)
Flexible parameters of the GMP may change from performance to performance. Flexible parameters depend on and equal:
- Overall movement duration - time can increase or decrease
- Overal muscle force generated during the movement
- Specific muscles used to perform skill
- movement direction
In GMP, parameter values are assigned by a performer to a GMP before:
performance of a skill –> can modify to meet the specific movement demands of the situation.
The ability to choose good parameters is partially what determines:
movement success or skill
ADAPTABILITY!!
(motor program theory) Schema =
2nd element of schmidt’s GMP theory.
- Abstract representation of a rule (or rules) governing movement.
Schemas contain the generalized rules that generate the spatial and temporal:
patterns to produce a movement
Schemas develop as result of:
movement experience
IN CONTRAST TO CLOSED-LOOP THEORIES (when hardwired preprogrammed movements dominate), A MOTOR PROGRAM containing general rules CAN BE APPLIED TO DIFFERENT ENVIRONMENTS or situations via open-loop process and GMP’s.
IN CONTRAST TO CLOSED-LOOP THEORIES (when hardwired preprogrammed movements dominate), A MOTOR PROGRAM containing general rules CAN BE APPLIED TO DIFFERENT ENVIRONMENTS or situations via open-loop process and GMP’s.
What are the 4 pieces of information that are subconsciously abstracted on each movement attempt? (motor program theory)
- initial conditions
- response specifications
- sensory consequences
- outcome of that movement
Initial conditions =
proprioceptive information of the limbs and body
response specifications =
parameters assigned to GMP
sensory consequences =
information about how the movement felt, looked and sounded (KP)
outcome of that movement =
KR compared to KP
When these 4 sources (initial conditions, response specifications, sensory consequences and outcome of that movement) of information are stored in memory following a movement attempt what happens?
the brain begins to develop a schema
With each movement attempt, the schema _____________________?
becomes stronger
- with practice you develop a motor response schema
What are 2 motor response schemas?
- recall schema
2. recognition schema
Recall schema =
organizes an appropriate motor program capable of initiating and controlling the desired movement
the recall schema provides parameter values to the GMP after observing:
your intentions and the situation
The recognition schema =
evaluates the last executed movement based on initial conditions, actual past outcomes, and past sensory information
The recognition schema, allows you to know when you’ve made and error,
just by feel
- error signal updates recall schema
According to the motor program theory, motor learning, consists of continuous processes that update the recall and recognition schemcas with every:
movement that is made
According to the motor program theory, the learner decides what movement to execute in a given situation by subconsciously retrieving the GMP from memory, based on the:
existing schema and parameters
According to the motor program theory, the desired movement is organized in advance by the GMP and sent to the body to:
execute it
If the GMP contains all the information needed to carry out an action, the movement is controlled once the GMP is issued through:
an open loop control
If it’s necessary to continually evaluate the accuracy of the action, the movement is controlled once the GMP is issued through:
close-loop control
Control may also vary according to the skill level of the:
performer
As proficiency increases, control transitions on a continuum from:
closed toward more open loop
In the motor program theory, open loop theory of motor control combines:
- basic idea of a schema (abstract generalization of rules governing movement
- idea of a generalized motor program (GMP)
In the motor program theory, for a given class of movement, we extract info from:
each movement experience (repetition)
In the motor program theory:
• construct schemas that enable movement in different situations and circumstance, the schema revises with ____________.
• The stronger the schema, ________________.
• Task of instructor is to devise activity to __________________.
- experience
- the more skilled the performance
- strengthen schema
Dynamical systems theory =
movement theory of dynamic interaction between person, task and environment
The dynamical systems theory argues motor program-based theories insufficient to account for control of:
complex movements
(DST) Bernstein - control is distributed/shared b/n the CNS, PNS, and EN rather than:
a hierarchical top-down (brain to periphery) control
(DST) Bernstein - emphasizes the situation-dependent (EN) _____________________.
mechanics of movement
(DST) Bernstein - movement patterns emerge (self-organize) as a function of the __________________ placed on it.
constraints.
In the dynamical systems theory, constraints =
boundaries that limit movement capabilities
What are 3 constraints of the DST
- individual (organismic)
- environmental
- task constraints
Individual constraints =
- body shape, weight, height
- personality, emotional, motivation
- cognitive/perceptual, decision-making skills.
environmental constraints =
gravity, temperature, light, wind, etc
task constraints =
- goals
- rules
- objects or machines
What are the 3 basic concepts of the dynamical systems theories?
- Self-organization
- Attractor states
- Phase shifts
see slide 37
see slide 37
self-organization =
movement self-organizes the available degrees of freedom into a single functional unit
During self-organization, new patterns may spontaneously emerge as a result of:
changing constraints placed on the learner
Self-organization involves skilled action that results when CNS constrains functionally specific collections of muscles and joints, i.e.
synergies and coordinative structures
- may be developed through practice or exist naturally
In the dynamical systems theory, coordinative structures/synergies =
- grouping of muscles and limbs that work together as a functional unit
- involve inherent neural pathways, biomechanical properties of muscles and limbs, and learned behaviors
List 3 examples of the coordinative structures/ synergies (DST):
- coupling b/n opposite limbs during bilateral movements
- arm/hand movements are predisposed to move with same relative time either in same direction (in-phase) or exactly opposite (antiphase)
- limbs are coupled based on sensory input from contralateral limb (try walking while swinging one arm faster than the other)
What is the key concept with attractor states (DST):
movement systems prefer states of stability
** does not mean invariance
In attractor states (DST), person, task and EN all affect how the system organizes:
• Can tolerate:
• If constraints change enough:
- can tolerate a fair amount of variability
* if constraints change enough, the system can become unstable
In the DST, control parameters =
the variables that, when increased or decreased, will cause change throughout the entire system (metronome speed)
In the DST, order parameters =
parts of the system that define or describe the movement
example: run vs walk - double vs single foot contact, vertical translation of center of mass
In the DST, phase shift =
when distribution is great enough (eg. speed of treadmill increases) the system may self-destruct or be forced to transition to a new stable attractor state
In the DST, phase shift concept, changes can be ___________ and abrupt or may slowly evolve over time
nonlinear
During the phase transition/ phase shift concept in the DST:
•walk on a treadmill @ 1.5m/s
• increase the speed while you are walking to 3.0 m/s what happens?
you will eventually reach a velocity that will force you to switch from walking to running
How do we use the Dynamical systems theory from a training/rehab perspective:
• it may be necessary to purposefully cause destabilization to promote new and better system functioning
What is the goal of how to use DST from a training/ rehab perspective?
to identify & manipulate control parameters (tempo, or speed, and force) to encourage a phase shift from a stable, but ineffective movement pattern to a more efficient movement pattern
Provide a clinical research example of how DST was been used:
stepping in tie to fast metronome resulted in improved coordination between arms/legs in patients post-stroke, and increased cadence in Parkinson’s disease
Why does destabilizing (DST) not always have a positive consequence?
- injuries: can cause detrimental compensations
- destabilizing one variable may not lead to the change you want ( improving strength may not affect sport performance)
- fatigue may be positive (stimulate tissue adaptations) or negative (erode coordination)
What are 2 limitations to the DST?
- presumption that CNS has nonspecific role in movement control [person (and nervous system), task, and environment have equal roles
- evidence supporting dynamical systems is only from continuous movements
