Lecture 2.3 - Motor Programs Flashcards
What is open loop control?
Includes the executive and the effector but no sensory feedback
Generally there is more error due to how quick it is and a lack of sensory refinement
T or F: Open loop control works best for rapid, discrete movements within stable and predictable enivronments
True
What do motor programs specify?
➔ Particular muscles used for the action;
➔ Orders of muscle recruitment;
➔ Forces of muscle contractions;
➔ Timing and sequencing of actions;
➔ Duration of each action segment.
Is open loop control non-conscious?
Yes, because there is no sensory feedback
T or F: The M2 reflex can affect open loop control because of their synapses
The M1 reflex can affect the effector
True
What was the Lashley study of deafferentation?
- Studied deafferented patients with loss of sensory info from their lower limbs
- They could still move and position their legs with reasonable accuracy despite having no sensory input
- This shows that motor programs could still be executed without sensory feedback/input
- These patients use open-loop pathways since their is no sensory feedback when the afferent nerve is cut
Sensory neuropathy = lost sensory feedback
*As long as visual information is still available
What was the Taub and Berman study of deafferentation?
- Deafferented monkeys maintained capability to perform motor skills
- Still able to perform open-loop movements with little to no impairment
- Movement was clumsy though and not very optimal, but still able to complete the movement
Deafferentation = still able to perform open-loop movements, bye bye closed loop
Nice
What do both deafferentation studies prove?
Both proved motor programs exist
T or F: Closed loop / sensory control is required for finer and controlled movements, and movements that require more duration / modification
True
What was the Henry & Rogers study?
- Studied simple reaction time (RT) and response complexity
- Found that there is a direct relationship between complexity of a motor program and the duration of reaction time
- Each indiviudal given a response with a different complexity:
a. finger lift
b. finger lift and reach and grasp a ball
c. finger lift, reach and hit ball, touch a button, reverse direction to strike a second ball - More complex response = longer reaction time
- Affects response programming and motor programming, does not affect stimulus identification and response selection because the responses are given
Proves motor programs exist, as all instructions were provided so that is inputted to the effector
If sensory feedback is involved, all RT’s should be the same despite having a more complex response
Describe muscle activity patterns (Wadmen et al. 1979 study)
Study electrical activity of muscles during
movement production.
➔ Wadman et al. (1979)
◆ Examined muscle activity patterns during rapid
movement.
- Put EMG on muscles to examine readings, EMG on agonist and antagonist muscle
- Rapid elbow extension to touch target
- At random intervals, elbow extension is blocked
- If we were FULLY reliant on sensory feedback, the motor program would change instantly
- However, the block came so quick that the movement output had to be completed, so it pushed against the block until motor program/output completion
- Showed that motor programs do exist
What was the Slater-Hammel (1960) study?
- Studied the ability to stop a movement at different stages of preparation
- Movement: - Make rapid movement to a target -> stop movement if stop signal is given
- Stop signal is at 800ms, patients can have varying degrees of start time i.e. 100ms after start of clock, 700ms
If patient could not stop, that would mean that the motor program is already outputted and the entire movement has to be completed before another can begin - open loop control
If patient could stop, that would mean their sensory feedback is active and they are using closed loop control
Findings:
- If “stop” signal is given too late in RT interval,
movement is still executed.
- Movement commands are pre-structured or
programmed in advance, then executed as unit.
- Once movement is planned, and internal “go”
signal is given, response is initiated.
Body can start moving 130ms-150ms after the go signal, but once it gets to 150-170ms, we cannot stop its movement
Remember <150ms before stop signal = we cannot stop the movement or the likelihood of stopping drops drastically
Go signal ~ 130-150ms
Point of no return ~ 150-170ms
What is a generalized motor program (GMP)
Refers to a motor program for a class or family of actions rather than specific actions
Defined by:
Invariant features - make the pattern appear the same time after time - allows for consistency in the same class of movement
Surface features (or parameters) - allow changes in the performance of a given skill - allows for differences within the same class of movement
i.e. throwing different sized balls. GMP’s allow you to group these in a similar class. Invariant features allow you to output the same throwing mechanics, surface features allow you to accomodate the differences in weight of the ball, speed of throwing the ball, size of the ball, etc.
How did the Armstrong (1970) study garner support for GMP?
Variations in movement time show similar but compressed patterns.
This is due to faster vs slower throwing task
EMG pattern is very identical but the slower one had larger waves due to it taking longer because it IS SLOWER
How did the Hollerbach (1978) study garner support for GMP?
Variations in movement amplitude of handwriting showed similar patterns of acceleration and relative timing of muscles
Despite how fast an individual wrote a specific word, the EMG readings for it were very identical - variations = slightly condensed or spread out- due to surface parameters
*The same GMP will be used for the same word regardless if you wrote it quicker/bigger/smaller
