Motor Control & Development

Definitions

• Motor Control:
    - The study of the nature of movement.
    - The ability to regulate or direct essential movement.
    - Consists of 4 Levels of Motor Control.

• Motor Learning:
    - The study of the acquisition or modification of movement.
    - Focuses on how we change things.
    - Consists of 3 Stages of Motor Learning.

• Motor Skills:
    - Learned through interaction and exploration of the environment.

• Motor Development:
    - The evolution of changes in motor behavior occurring as a result of growth, maturation, and experience across the life span.

4 Levels of Motor Control

1. Mobility:
      - Ability to initiate movement from one position to another.
      - Examples:
        - Rolling from supine to sidelying.
        - Moving from sit to stand.

2. Stability:
      - Ability to maintain a posture, which is static in nature.
      - Examples:
        - Prone on elbows.
        - Kneeling.
        - Standing on a Bosu ball.

3. Controlled Mobility:
      - Ability to move within a weight-bearing position while maintaining posture.
      - Dynamic in nature (while moving).
      - Examples:
        - Weight shifting in standing or quadruped.
        - Doing one-arm movements while in prone on elbows.
        - Lower trunk rotation in sidelying.

4. Skill:
      - Consistently performing tasks and controlling the environment.
      - Highest level of motor behavior.
      - Examples:
        - Walking.
        - Climbing stairs.
        - Tying shoes.

3 Stages of Motor Learning

1. Cognitive Stage:
      - High levels of concentration are required.
      - Patients need to focus and participate.
      - Vision assists in guiding the learning process.
      - Characterized by high error rates and a closed environment.
      - Example: Hospital patients learning new tasks focusing on 'what to do'.

2. Associative Stage:
      - Increased independence in distinguishing correct vs incorrect performance.
      - Environment becomes more open with fewer cues.
      - Characterized by decreased need for concentration and cognition.
      - Example: Patients focusing on 'how to do it'.

3. Autonomous Stage:
      - Activity is performed with minimal cognitive control.
      - Characterized by automatic responses and adaptability to distractions.
      - Example: Outpatient patients focusing on 'how to succeed'.

Feedback in Motor Learning

• Importance:
    - Essential for the progression of motor learning.
    - Patients rely on both intrinsic (internal) and extrinsic (external) feedback.

• Types of Feedback:
    - Intrinsic Feedback:
      - Also known as closed feedback.
      - Involves internal sensory feedback during movement (visual, vestibular, proprioceptive).
    - Extrinsic Feedback:
      - Also known as open feedback or augmented feedback.
      - Comes from external sources (coaches, therapists).
      - Types include:
        - Knowledge of results: outcome feedback (e.g., did the task happen?).
        - Knowledge of performance: feedback regarding the movement pattern used to achieve the goal.

Practice in Motor Learning

• Practice:
    - Refers to repeated performance of an activity to learn or perfect a skill.

• Types of Practice:
    - Massed Practice:
      - Practice time is greater than the amount of rest time.
      - Example: Outpatient sessions that keep moving.
    - Distributed Practice:
      - Rest time equals or exceeds practice time.
      - Example: Inpatient needing frequent breaks.

• Practice Sequence:
    - Blocked Practice:
      - Consistent practice of a single task in repetition.
      - Example Pattern: (111, 222, 333).
    - Random Practice:
      - Varying practice amongst different tasks.
      - Involves multiple exercises within a single session.

• Practice Order:
    - Blocked Order:
      - Repeated practice of a task or group of tasks.
      - Example: Focusing on one exercise at a time.
    - Serial Order:
      - Predictable and repeating order of multiple tasks.
      - Example: (123, 123, 123).
    - Random Order:
      - Non-repeating and non-predictable order.
      - Example: (123, 321, 213).

• Practice Strategies:
    - Mental Practice:
      - Imagining or visualizing the motor task without physical practice.
    - Part Practice:
      - Practicing individual components of a task before the whole.
    - Whole Practice:
      - Practicing the entire task altogether without fragmenting.

Motor Development

• Definition:
    - The evolution of changes in motor behavior due to growth, maturation, and experience across the lifespan.
    - Foundational skills typically learned in infancy and childhood.
    - Example Demonstration:
      - Different behaviors observed from infancy to teenage years when attempting to retrieve an object.

Role of Sensation in Motor Control

• Initially, sensation guides reflexes and movements, serving survival functions.
    - Reflexes include:
      - Rooting reflex.
      - Palmar grasp reflex.
      - Babinski reflex.

• As individuals mature, sensation is used for accuracy and fine motor control instead of purely reflexive responses.

Infant Reflexes

• Reflexes:
    - Automatic, unlearned responses aiding infant survival.
    - Certain reflexes persist, while others disappear as one grows.

Specific Infant Reflexes

1. Rooting Reflex:
      - Stimulation: Baby’s cheek stroked with finger or nipple.
      - Behavior: Head turns, mouth opens, sucking movements initiated.
      - Age: Birth to 3 months.

2. Palmar Grasp Reflex:
      - Stimulation: Pressure applied to the palm of the hand.
      - Behavior: Fingers flex, creating a strong grip.
      - Age: Birth to 4 months.

3. Plantar Grasp Reflex:
      - Stimulation: Pressure on the base of the toes.
      - Behavior: Toes flex.
      - Age: Birth to 9 months.

4. Moro Reflex:
      - Stimulation: Sudden dropping of the head into extension.
      - Behavior: Arms extend outward to the side.
      - Age: Birth to 5 months.

5. Startle Reflex:
      - Stimulation: Loud, sudden noise.
      - Behavior: Same response as Moro reflex.
      - Age: Birth to 5 months.

6. Parachute Reflex:
      - Stimulation: Holding the baby face down and lowering toward a surface.
      - Behavior: Arms extend forward, fingers spread apart.
      - Age: Begins around 8-9 months, persists for life.

7. Positive Support Reflex:
      - Stimulation: Weight placed on the balls of the feet when upright.
      - Behavior: Legs and trunk stiffen into extension.
      - Age: Birth to 2 months.

8. Walking/Stepping Reflex:
      - Stimulation: Supported upright position with soles on a firm surface.
      - Behavior: Reciprocal flexion/extension of legs, mimicking walking.
      - Age: Birth to 2 months.

9. Babinski Reflex:
      - Stimulation: Stroking the sole of the foot from heel to toe.
      - Behavior: Toes fan out, foot twists inward.
      - Age: Birth to 4 months.

10. Symmetrical Tonic Neck Reflex:
        - Stimulation: Head position, either flexed or extended.
        - Behavior: When head is flexed, arms flex and legs extend; when head is extended, arms extend and legs flex.
        - Age: 6 to 8 months.

11. Tonic Labyrinthine Reflex:
        - Stimulation: Position of the inner ear reflected in head position.
        - Behavior: Body and extremities extend when supine; flex when prone.
        - Age: Birth to 6 months.

12. Asymmetrical Tonic Neck Reflex:
        - Stimulation: Head turned to one side.
        - Behavior: Extended limbs on face side, flexed limbs on scalp side.
        - Age: Birth to 6 months.

Milestones of Motor Development

Protective Reactions

• Movements in response to rapid body displacement outside the base of support.

• Types of Protective Reactions:
    - Forward Protective Reactions:
      - Arm extension observed.
      - Age: 6-7 months.
    - Sideways Extensions:
      - Arms extend laterally.
      - Age: 7-8 months.
    - Backward Extensions:
      - Arms extended back.
      - Age: 8-9 months.

Balance

• Definition:
    - State of physical equilibrium and maintenance of control over the center of gravity (COG).

• Components of Balance:
    - Somatosensory Input:
      - Proprioceptive information regarding length, tension, pressure, pain, and joint position.
    - Visual Input:
      - Provides perceptual acuity concerning motion and orientation.
    - Vestibular Input:
      - Feedback related to head position and movement regarding gravity.

Balance Strategies

• Ankle Strategy:
    - Engaged during gentle displacements.
    - Posterior chain muscles activate sequentially (e.g., gastroc first, followed by hamstrings and trunk flexors).

• Hip Strategy:
    - Engaged during rapid displacements, bypassing ankles.
    - Activation involves trunk and hip muscles initially.

• Stepping Strategy:
    - Employed when hips alone cannot maintain stability.

• Suspensory Strategy:
    - Lowers the center of gravity to maintain balance.

Anticipatory vs. Reactive Posture

• Anticipatory Postural Control:
    - Activating adjustments in advance of voluntary movements.
    - Evaluated through voluntary movements requiring postural adjustments to counter predicted disturbances.

• Reactive Postural Control:
    - Automatic responses to unexpected external disturbances.

References

• Giles, S. M. (2020). PTAEXAM: The complete study guide. Scarborough, ME: Scorebuilders.

• Kisner, C. & Colby, L.A. (2012). Therapeutic Exercise (6th ed.). Philadelphia, PA: F.A. Davis.

• O’Sullivan, S.B. & Schmitz, T. (2014). Physical rehabilitation (6th ed.). Philadelphia, PA: F.A. Davis.