Understanding Motor Control

• Motor Control: The ability to regulate or direct mechanisms essential to movement.
• Motor control is the field that studies the nature of movement and how it's controlled.

Key Elements of Motor Control:

• The individual generates movement.
• Movements must meet the demands of a specific task,
• Movements occur within a specific environment.

System Overview

• Motor/Action: Involves the neuromotor and biomechanical systems; muscles and joints must be controlled in coordinated ways.
• Sensory/Perceptual: Involves peripheral sensory and higher-level processing.
• Sensory Component: Provides information regarding the state of the body and environment and includes vestibular, kinesthetic, proprioception, auditory, visual, and tactile input.
• Perceptual Component: Interpretation of sensory input
• Cognitive: Attention, planning, problem-solving, motivation, and emotion; it establishes intent or goals.

Stages of Information Processing in the CNS for Movement Production:

• Stimulus Identification Stage: Sensing, planning, and memory contact stage, which considers the state of the body, movement, and the environment, including memory based on past experiences.
• Response Selection Stage: This is the interpreting, planning, and deciding stage where a plan for purposeful movement is developed and a motor plan is generated, that are made up of stored motor programs.
• Response Programming: Involves translating, structuring, and initiating the stages when neural centers translate the idea for movement into muscular actions defined by a motor program.

Motor Program

• It's an abstract representation that, when initiated, results in a coordinated movement sequence.
• Motor programs free up the nervous system from conscious decisions.
• They utilize muscle synergies (functional linked muscles) to simplify control.
• Parametric specification is based on constraints of the individual, task, and environment.
• Response Execution: Represents the movement output and involves feedforward and feedback controls.
• Feedforward Control: Sending of signals in advance of movement to ready the system for incoming sensory signals.
• Feedback Control: Response-produced sensory information received during or after the movement and used to monitor movement output for corrective action.

Task Constraints:

• Task constraints include mobility, postural control, and upper extremity function.
• Discrete vs. Continuous: Discrete movements have a recognizable beginning and end; continuous, the performer decides when to end. EX: Discrete - gymnastics routine. Continuous - walking, skipping, jumping jacks.
• Open vs. Closed: Open movements are unpredictable and require adaptation; closed are fixed and predictable.
• Stability vs. Mobility: Stability involves a non-moving base of support; mobility involves a moving BOS (walking, running, jumping).
• Manipulation vs. Non-Manipulation: Manipulation involves upper extremity (UE) function; non-manipulation does not.

Environmental Constraints:

• Regulatory Features: Shape movement EX: cup size, height of step/chair, surface of ground.
• Non-Regulatory Features: May affect/influence movement but does not shape/conform EX: background noise, distractions.

Dual Task:

• Motor skills are the ability to perform a task while doing a secondary task (primarily cognitive or motor EX: walking and talking.

Simple Task:

• Simple motor program EX: kicking a ball one time

Complex Task:

• Involve multiple actions EX: kicking a ball while running

Theories of Motor Control:

• Reflex Theory: Early theory based on reflexes as building blocks of movement that are chained together EX: reflex chaining . This has many limitations.
• Hierarchical Theory: Builds on the reflex theory, realizing that reflexes are modified to adapt to tasks through CNS commands. The basic assumption is that the brain controls all movement/top-down. Limitations to this theory.
• Motor Programming Theories: Assumes we have patterned motor responses; hardwired neural connections allow stereotypical movement (central motor pattern or motor program). Incorporates top-down and bottom-up control. Limitations include that a central motor program cannot be only determinant of an action.
• Clinical implications that interventions should focus on retraining movements important to a functional task (not isolated muscles).
• Systems Theory: Integrates many previous theories and reflects current interpretation of nervous system function, describes the process by which various brain and spinal centers work together to produce movement while also considering internal and external factors.
• Systems theory reflects distributed model of control from many interacting systems, and it allows for flexibility of motor patterns that can adapt to the task and environment.