Motor Skill Acquisition: Theories, Neural Control, and Performance Insights

Adams Closed-Loop Theory of Motor Learning

Adams' Closed-Loop Theory emphasizes the crucial role of feedback in learning motor skills. Feedback also strengthens memory and the perceptual trace, both of which are central to acquiring a motor skill.

Weaknesses:

• Cannot explain fast movements, only slow, linear movements.
• Too many action plans create a significant storage problem in memory.
• Doesn't explain an individual's ability to perform novel skills.

Schmidt's Schema Theory: A Cognitive Approach to Motor Learning

Schmidt's Schema Theory proposes cognitive mental constructs that describe a rule developed to overcome the weaknesses of Adams' theory. It utilizes the Generalized Motor Program (GMP), which is an abstract memory of a movement. The GMP contains the temporal and spatial patterns of muscle activity, emphasizing pre-planning and programming. Once abstracted, certain rules or principles of operation can be developed and used to guide action.

Weaknesses:

• Cannot explain the development of new patterns of coordination.
• Many movements and changes we perform are not pre-planned.
• Does not fully account for changes due to environmental shifts.
• Overemphasizes the role of cognitive processes.

The Reflex Arc: Pathway of Involuntary Response

The reflex arc describes the neural pathway that mediates a reflex action. It typically involves the following sequence:

1. Receptor
2. Sensory Neuron
3. Central Nervous System (CNS)
4. Motor Neuron
5. Muscle (Effector)

Understanding Motor Skill Performance Curves

The shape of performance curves depends on several factors:

• The nature of the task learned.
• The individual learner.
• The conditions in which the task is performed.
• How performance is measured.

Scoring sensitivity can significantly affect the curve's shape; if not scaled correctly, it can skew the results. Learning plateaus can occur due to several reasons:

1. Many transitions between stages: During this process, new strategies are often tried, which may lead to a temporary plateau.
2. A hierarchy of subskills: Complex skills require the acquisition of various subskills, and a plateau can represent a transition between these levels.
3. Psychological factors.
4. Physical factors.

Factors Influencing the Effectiveness of Motor Skill Modeling

The effectiveness of modeling (observational learning) in motor skill acquisition is influenced by several key variables:

• The developmental characteristics of the observer.
• The elements and quality of the demonstration.
• The type of rehearsal strategies employed by the observer.

The Corticospinal Tract: Pathway for Voluntary Movement

The corticospinal tract originates in the motor and sensory cortex, with large, long axons primarily from the primary motor cortex (M1), but also from the premotor area (PMA) and supplementary motor area (SMA). It goes uninterrupted, synapsing directly with motoneurons in the spinal cord. Many of these axons are myelinated, ensuring that motor commands reach their destination at high speed.

Approximately 75% of these axons decussate (cross over) at the medulla, forming the lateral corticospinal tract (CST), which controls the opposite side of the body.

Functions:

• Controls fine, skilled movements.
• Modulates the flow of sensory information.
• Enables rapid adjustments to ongoing movements.