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