Motor Programs Flashcards
What are motor programs?
A set of motor commands that is pre-structured at the executive level and that defines the essentials of a skilled action
What is an open loop?
Centrally determined, prestrucutred commands sent to the effector system and executed without feedback
What are degrees of freedom?
The component of the control system that can vary independently and that are controlled to produce effective action… how many ways a thing can move/ how many things change
Where does a voluntary action start?
Motor program under open loop control
How does an open loop function?
Preplanned instructions specifying function, sequence and timing
Once the program starts the system continues to completion without modifying
No ability to detect and correct errors
What are the uses of the open loop?
For rapid discrete movement
In predictable and stable environment
To initiate movement
Eventually to control long strings of learned/ rehearsed movements
Initiated movements as open-loop motor programs progress unchanged if:
1) they are too fast for feedback to register
2) There is no error and/or no change in environment
What is the evidence for motor programs?
1) Reaction time and movement complexity
2) Deafferntiation
3) Central Pattern Generation (CPG)
4) Effects of blocking a limb
5) Inhibiting (Voluntarily Stopping) Actions
What is reaction time and movement complexity?
The more complex a movement is, the longer it takes to prepare, resulting in longer RT
1) The more elements, the longer the RT
2) The more limbs involved, the longer the RT
3) The longer the movement (in time), the longer the RT
What is deafferntiation experiments
A surgical procedure in which an afferent pathway (one carrying sensory info toward CNS) is cut, prventing nerve impulses from the periphery from reaching the spinal cord
1) Sensory feedback is not necessary for movement production
2) Supports theory that motor programs can be organized and performed in an open loop framework
What is central pattern generation?
A centrally located control mechanism that produces mainly genetically defined, repetitive action such as locomotion or chewing
1) A single simple input can result in a complex repetitive behavior
2) Similar to a motor program, but refers to inherited rather than learned skills
What are the effects of blocking a limb?
Accelerate = tricep
Brake = bicep
Start to brake even though the hand is not moving
1) the first 100ms of a movement is preprogrammed and cannot be influenced
2) Aspects of the program cannot be stopped even if they are useless( or detrimental)
What happens what you inhibit (voluntarily stopping) action?
If we can execute motor programs even when the limb is blocked, can we work backwards and determine what the point of no return is for executing a program
Slater - Hammel experiment
- most trials: participants told to stop hand on 10
- some trials: experimenter stops the hand. Participants told to make no response
What are postural (anticipatory) adjustments?
1) sinse the shift of center of gravity would result in loss of balance , postural support is programmed to happen before lift
2) Should consider the postural support and subsequent lift as on programmed action
What are flexible reflexes?
Reflex-reversal phenomenon: A special case of reflex activity involving different responses to the same stimulus
What is a reflex?
Stereotyped, involuntary, automatic and usually rapid response to stimuli
What does a motor program need to do?
1) define and issue commands to the muscles needed to produce (initiate) the goal movement
2) Coordinate the many degrees of freedom needed to produce an effective and efficient action (force, timing, duration)
3) Specify and initiate any prliminary postural adjustments needed to support the upcoming action
4) Moderate reflex pathways
What is the storage problem?
Would need infinite memory to store programs for controlling the infinite number of movements people can produce
What is the novelty problem?
How do you create motor programs for a movement that you have never produced before?
What is the general motor program theory?
A motor program that defines a pattern of movement rather than a specific movement; can change parameters to produce movement variation that meet different environment demands
What are parameters?
The variable inputs to a generalized motor program which result in different movement
What are invariant features?
The characteristics of a movement that stay the same when the surface features (parameters) of the movement change
What is relative timing?
A measure of the temporal structure of a movement ,in which the ratios among the duration of various movement features are used to define the temporal pattern (fundamental timing principle)
-The % of total movement time spent in each part of the task is the same regardless of total movement time
What are classes of movement?
A group of movements that share the same relative timing fingerprint
Throwing
- can vary throw distance but once capability is exceeded, switch to different motion
Walking
-can walk on a treadmill at a velocity of speed while keeping a consistent gait, at some point must switch to running
What are examples of parameters?
Movement time (how fast) Movement amplitude (how far) Effector (what thing are you moving to make change)
What is movement time?
Fundamental timing structure: the sequencing and timing of a movement that defines the underlying pattern
What is movement amplitude?
Real world example of analysis of general motor programs in handwriting
