Lecture 18 Flashcards
There are more degrees of freedom in the body
than required to achieve a given task
Higher levels of CNS activate lower levels
(motor units) which temporarily grouped as muscle synergies
Motor learning
How we to do this efficiently and to cope with all the variability that life throws at us
The Origin of motor program
Many researchers believe motor commands are represented and stored in the central nervous system
-Memory drum - computer analogy
-Motor program
Open loop control difference to closed loop control
Both = Movement executive- movement commands - movement effectors
Closed loop has feedback from movement effectors to movement executive
Information processing demands of movement
Input
Perception
Decision making
Executing
Feedback
Indirect perception (Cognitive Approach)
Brain assigns meaning to sensory information
Information processing model
It soon become apparent that motor programs for each skill unlikely
- Schmidt “schema theory”
- Key movement parameters are modified for generalised motor programmes (GMP)
Generalised motor programs
Invariant features
Parameters
Invariant features
Sequence of actions
Relative timing
Relative force
Parameters
Muscle selection
Overall duration
Overall force
Neurocomputational theories
More recently neurophysiological research has linked different brain regions to specific functions
The field of robotics
Has identified that more complex (parallel)programming is needed to cope with / learn in ‘messy’ environments
- Artificial intelligence
-Predictive processing
-Sensory systems directly map to actuators
4 areas of cognitive theoretical constructs
-Open, closed loop control
-Information- processing
-Schema theory
-Neurocumputational
Ecological Psychology
Movement is much more complex than simple input output relay of information from the brain to the other systems
Ecological psychology ( actions are determined by many factors)
-Internal (goals, prior experiences and capabilities of the individual)
-External (what is available in the environment)
Direct Perception (Ecological approach)
-Energy transformations
-No intermediate stages between perception and action
-Animals sensory systems have evolved to pick up this information
-Looming response in animals and human babies
Example of direct perception (Tau)
Optical variable ‘tua’ directly specifies time to contact
Dynamical systems Jargon
Attractor
Control parameter
Rate limiter
Phase shift
- Attractor : Bench pressing with good form
- Control parameter: Increasing the amount of weight used in a bench press
-Rate limiter : Increasing the weight used in a bench press beyond the capability of the exerciser
-Phase shift: Change in the correct form caused by too much weight used in bench press
Self organisation via contraint
3 Classes of contraints
Organismic
Task
Environmental
Three classes of contraints provide…
A coherent framework for understanding how coordination patterns emerge during goal-directed behaviour
Cognitive approaches
-Top down
-Body is controlled (enslaved) by the brain
-First information is processed and understood (input), then motor program is selected and released (output).
-Mix of predictive processing and reflexive control of muscle
Ecological Dynamics
-Bottom up
-Individual - in -environment is a complex, dynamical system
-Co-ordination emerges from many interacting constraints
-Close interrelation between perceptual systems and motor systems
