Lecture 10a, Generalized Motor Programs

Question 1

What are the pros of the motor programs?

Answer 1

1) you don’t have to wait for feedback (beneficial for very fast actions)
2) provides a way of coordinating actions (many “degrees of freedom”) - more packaged in advance so we do not have to think about individual degrees of freedom
~ rather than having to control all the independent states of the various muscles and joints, the motor program concept gives a way of thinking about coordinated actions

Question 2

What are the cons of motor programs?

Answer 2

storage problem and novelty problem

Question 3

Storage Problem

Answer 3

1) storage problem (many different motor programs needed for different types of actions - do we need to have separate motor programs for every separate actions)
- how many throwing-related motor programs would we need to store in LTM, as an in-field baseball player? ~ a lot!
◦ solution: store only general
(template) motor programs templates containing common features
- template that contains main ingredients but we tune or scale them depending on circumstance
- rather than storing every instance we store generalized features

Question 4

Novelty Problem

Answer 4

2) novelty problem (how are you able to do something if you do not have a motor program if you have never done it - we can use the template to program it appropriately as it provides a general template)
- how do we make new throws when we are standing at an unpracticed distance, or ball is new?
◦ solution: store only general
(template) motor programs
that can be tuned to novel
situations -> templates that
can be ‘tuned/adjusted’
“PARAMETERIZED”

Question 5

Generalized Motor Program (solution)

Answer 5

• memory for class of actions/patterns of movement and modified based on desired outcome
• every movement does not require a separate motor program
• GMP: a more “general” motor program, like a skeleton /template, for a general type of action
• you can parameterize it for the distance as you move away further for shot (the same action, generalized motor program) - most of the time it is adjusting forces so that you can scale the output of you throw to the required distance

Question 6

Invariant Features

Answer 6

fixed features that define the motor program (this is the GMP)
◦ primarily solves storage
problem
- what we are storing at the fixed features solves the storage problem

Question 7

Parameters

Answer 7

flexible features that define how the motor program will be executed
◦ primarily solves novelty
problem (we have general
template, just need to find
right parameter based on
our previous experience with
that action)
- tune and adjust skeleton to the circumstance we are in
- scaling a generalized motor program to throw further or nearer for example

Question 8

GMP can be identified by its invariant (fixed) features (like fingerprints)

Answer 8

• forms the basis of what is stored in memory
• (relatively) consistent from one performance of an action to another
• even those those actions may differ in terms of certain parameters
• invariant features: the fingerprints of the motor program

Question 9

Three Invariant Features

Answer 9

1. relative timing - rhythm, patterning (relative timing between events)
2. relative force
3. order of events
   might want to think about “relative” as proportional

Question 10

Invariant Features: 1 = Relative timing

Answer 10

internal rhythm of the skill
- relative timing of events/actions/muscle activation is invariant (fixed pattern) & remains constant within a GMP
- “relative” meaning % or proportion of overall duration of skill for each component of the skill
- 4 phases of a baseball throw (knee up>step>elbow flex>throw) - to see signature of player you would want to check their timing if they are relatively consistent across different variations of the same throw
- there tends to be patterning that is relatively consistent if you are watching someone do the same skill

Question 11

Invariant Features: 2 = Relative force

Answer 11

amount of force produced by muscles remains in constant proportion from movement to movement
- both the muscles would be scaled in same manner so they proportionally remain the same (if muscle 1 was doubled, muscle 2 would also be doubled)

Question 12

Invariant Features: 3 = Order of events

Answer 12

order of events, components (or muscles, if using the same muscles) is invariant or fixed
- consistency in order
- it can be in terms of muscle level or component level (knee up < step < elbow flex < throw)
- invariance = the property of remaining unchanged regardless of changes in the conditions of measurement