Motor Control Theories

Scientific Theory

“A well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment”.

A good theory should satisfy…

-Must accurately describe a large class of observations

-Must make definite predictions about the results of future observations

A good motor control theory…

-Explain how the nervous system produces coordinated movement such that we are able to successfully perform a variety of motor skills in a variety of environmental contexts.

Coordination

The patterning of head, body, and/or limb motion relative

to the patterning of environmental objects and events

Degrees of Freedom

the number of independent elements or components in a control system and the number of ways each component can vary

e.g., planes of motion of a joint or individual muscles or individual motor units

Degrees of Freedom Problem

Successfully controlling the many independent, redundant components of the musculoskeletal system

What is the goal in understanding the degrees of freedom problem

How can we constrain the system’s many degrees of freedom so that it could produce the specific result

Open-Loop Control systems

a control system in which all the information needed to initiate and carry out an action as planned is contained in the initial instructions to the effector

Motor Program

A memory representation that stores information needed to perform an action

(prestructured set of commands that defines and shapes an action)

General Content of Motor Programs

Specification of Anticipatory Postural Adjustments (APA’s)

Postural muscle activation patterns

Anticipation of what the task requires

2) Specification of primary/focal action

Generalized Motor Program Theory

Definition of GMP:

•abstract representation that produces a general class of movements and can vary along certain dimensions (“parameters”)

•GMPs contain the fundamental pattern of a class of actions

•Provides the basis for controlling a specific action within the class of actions

Invariant features of GMP’s

These features are the signature of a GMP and form the basis of what is stored in memory.  They are characteristics that do not vary across performances of a skill within class of actions.

•Order of events/components (ie. spatial pattern)

•Relative Timing

•Relative Force

Parameters of GMP’s

Parameters: movement-related features of the performances of a motor skill that can be varied from one performance to another.

•Muscle Selection

•Overall Duration

•Overall Force