Motor Learning Fundamentals

Introduction to Motor Learning

• Motor control is how motor behaviour is organized, produced, and modulated.
• Motor development involves age-related changes in motor behaviour.
• Motor learning involves gaining the capacity for a skilled action.
• Motor recovery is regaining movement skill lost through injury.

Retention vs. Generalizability

• Retention refers to whether a task can be repeated after a break.
• Generalizability refers to whether a task can be repeated with different initial conditions.
• Learning is a permanent change in the capacity to produce a motor task.
• Schmidt's definition of motor learning includes processes associated with practice or experience that lead to a permanent change in skilled action capability.
• The power law of practice states that early improvements are faster, but later improvements are slower.
• Learning cannot be directly measured, but can be observed through behavior.
• Motor performance is observable behavior attributable to learning.
• Motor performance depends on state variables such as fatigue, anxiety, and motivation.

Skills as Tasks

• Discrete skills have well-defined beginnings and ends and brief duration, such as a TUG (Timed Up and Go) test
• Serial skills are a series of discrete skills in a specific sequence, such as making a sandwich.
• Continuous skills are repetitive or rhythmic with no defined beginning or end, continuing until a goal is complete, such as walking or fly-fishing.
• Closed skills are performed in stable, predictable environments.
• Open skills are performed in changing, unpredictable environments.

Skills as Performance Proficiency

• Guthrie's three characteristics of skills include consistency, efficiency, and timing.
• Consistency is the reliability of the outcome.
• Efficiency is minimum energy expenditure.
• Timing refers to minimum movement time or reaction time.
• In rehabilitation, effectiveness, safety, and efficiency are key.

Explicit vs. Implicit Learning

• Explicit or declarative learning requires conscious processes.
• It involves memory for facts and events.
• Information with explicit learning is consciously recalled.
• Implicit or non-declarative learning does not require conscious processes.
• Non-associative learning includes habituation and sensitization.
• Habituation is decreased responsiveness due to repeated exposure.
• Sensitization is increased responsiveness following a noxious stimulus.
• Associative learning includes classical and operant conditioning.
• Classical conditioning involves a conditioned stimulus paired with an unconditioned stimulus, like Pavlov's dog experiment.
• Operant conditioning is the relationship of behavior to consequence.
• Procedural learning involves tasks performed automatically without conscious thought.
• Procedural learning develops slowly through repetition.

Motor Control Theories

• Adam's Closed Loop Theory involves practicing under variable conditions.
• It uses sensory feedback to control movement during execution.
• Adam's Theory requires two memory states: memory trace and perceptual trace.
• Memory trace produces the movement.
• Perceptual trace evaluates the movement in progress.
• Adam's Theory emphasizes accuracy and repetition.
• The theory is not useful for rapid movements.
• Schmidt's Schema Theory emphasizes accurate repetition and transferability.
• It accounts for learning and control of rapid skills.
• Schmidt's Theory emphasizes open-loop processes.
• Schmidt's Theory requires two memory structures: recall schema and recognition schema.
• Recall schema is responsible for movement production.
• Recognition schema is responsible for movement evaluation.
• Schmidt's Theory explains performance in novel situations, but does not explain first-time movements or immediate acquisition of new coordination patterns.
• Newell's Ecological Theory helps patients explore the environment and regulatory cues.
• It focuses on the perceptual/motor workspace.
• Individuals learn to scan the environment for perceptual cues.
• Cues are "mapped" to actions.

Stages of Motor Skills

• Fitts and Posner's Three-Stage Model includes cognitive, associative, and autonomous stages.
• The cognitive stage, also known as the verbal motor stage, involves talking things out.
• In the cognitive stage, an understanding of the task is developed.
• A high degree of attention is required during the cognitive stage.
• The associative stage involves refinement of the skill.
• The associative stage includes the ability to detect and correct errors.
• The autonomous stage appears after months or years of practice.
• In the autonomous stage, skills become automatic.
• Low attention demands characterize the autonomous stage.
• Bernstein's Theory focuses on controlling degrees of freedom.
• The novice stage involves simplified movements that are inefficient and inflexible.
• The advanced stage involves the release of degrees of freedom and the disappearance of co-contraction.
• The expert stage involves the release of all degrees of freedom.
• Demonstrates efficiency with increased speed and decreased energy during the expert stage.
• Gentile's Two-Stage Model focuses on the learner's goal and type of skill.
• The task dynamic stage involves an understanding of the goal of the motor task.
• The task dynamic stage involves developing movement strategies, and understanding environmental influences.
• The fixation/diversification stage involves fixation for closed skills and diversification for open skills.
• Fixation, for closed skills, leads to consistency and decreased variability.
• Diversification, for open skills, involves developing the capacity to adjust varying demands.
• An example of diversification includes walking on different surfaces.
• Errorless learning involves learners performing tasks without making errors and is commonly seen in dementia patients.
• Error augmented learning can be used to enhance the error signal to promote changes to the CNS.
• The text gives the example of patients with chronic stroke with gait asymmetries

The Physiology of Motor Learning

• Neuroplasticity is the nervous system's ability to adapt and change throughout life in response to environmental needs and demands.
• Neuroplasticity is most prominent during development.
• Neuroplasticity allows neurons to change their function, chemical profile, or structure, retained for more than a few seconds.
• Neuroplasticity occurs in three main contexts: neurodevelopment, learning, and recovery after injury.
• Henry Molaison's case provided insight into memory systems.
• Medial temporal lobe and hippocampus are vital for long-term declarative memories.
• The medial temporal lobe is not the ultimate storage site for knowledge.
• Memory systems include declarative (explicit) and procedural (implicit) memory.
• Declarative memory involves the frontal brain, anterior cingulate, head of caudate, medial temporal lobe, and hippocampus.
• Procedural memory involves the basal ganglia, cerebellum, and motor cortex.

Measuring Neuroplasticity

• Synaptic Efficiency measures changes in pre- and post-synaptic neurons, or long-term potentiation.
• Neuronal Morphology involves observing structural changes in neurons.
• Cortical mapping involves tracking changes in cortical representation.
• Brain imaging techniques include:
  • Magnetoencephalography (MEG): millisecond time scale, uses magnetic fields.
  • Functional MRI (fMRI): second time scale, tracks oxygenated blood flow.
  • Positron Emission Tomography (PET): minute time scale, uses radioisotopes to measure metabolic activity.
• Transcranial Magnetic Stimulation (TMS) uses pulsed magnetic fields to temporarily excite or inhibit synaptic efficiency.

Developmental Neuroplasticity

• Involves the genesis of neurons through cell proliferation, migration, and differentiation.
• Involves the genesis of connections through axonal growth, neurotransmitter synthesis, and synaptogenesis.
• The elimination of cells and synapses includes pruning and refinement during late pregnancy to adolescence.
  • Cell death and retraction of projections occurs.
  • Apoptosis is genetically programmed cell death.
• Trophic factors are life-sustaining substances, such as neurotrophins, which act as nerve growth factors.

Activity-Dependent Synaptic Rearrangement

• Synaptic segregation occurs during a critical time period, where neurons firing together strengthen function.
  • Example: in the developing visual system, both eyes initially overlap and then segregate into distinct regions in the LGN.
• Synaptic convergence occurs during a critical time period, where integrating signals from multiple sources enhances processing.
  • Example: in the retina, multiple photoreceptors converge onto a single bipolar or ganglion cell.
• During development, global and drastic changes occur during critical periods.
• In adulthood, changes in synaptic strength are slower.
• Cortical areas involved in implicit learning: hippocampus & medial temporal lobe
• Methods of brain imaging from fastest to slowest: MEG, fMRI, PET
• Cellular apoptosis and synaptic pruning are not expected to occur during neural development? False

Rules of Synaptic Plasticity

• Hebb's Hypotheses outline the rules of synaptic plasticity.
  • Neurons that fire together, wire together, strengthening the connection.
  • Neurons that fire out of sync, lose their link, weakening the connection.
• Learning (late LTP) is tied to Molecular Changes:
  • Phosphorylation of proteins in neurons changes synaptic effectiveness
  • There is an increase in number of post synaptic AMPA receptors
  • Protein synthesis produces synaptic modification over time

Hebbian Learning

• How is the pairing happening which induces Hebbian's learning? As they are paired more frequently, the response becomes larger
• Mossy fibers → air detection (via parallel fibers): kinesthetic information (example: at the eye doctor blowing air into eye ; wants to make you blink) → simple
• Climbing fibers: error signal → complex
  • Increased complex spikes = more errors reducing efficiency of mossy/Purkinje fibers

Plasticity and Learning Shumway-Cook and Woollacott

• Habituation and Sensitization are both processes that result in an increase or decrease in response through exposure to sensory information → Non-associative
  • Sensitization: example back pain; stimulus causing reaction over an amount of time
  • Habituation: adapting until you decrease the outcome of the stimulus
• Associative Learning: classical and operant condition -> Pavlov's dog
  • Long-Term Synaptic Potentiation
  • Strength of stimulation and reward = timing of stimulation and reward
• Procedural Learning: more complex (motor cortex and cerebellar) → trial & error
  • Gilbert and Thatch: monkey learning to return lever → adapting to change
  • Example: a child learning to ride a bike without training wheels

Contributions to Procedural Learning

• Motor cortex contribution: learning sequential finger movement task
  • Early: decrease in reaction times → increase cortical maps for fingers
  • Middle: recognizes a sequence is present but does not state sequence → not perfect
  • Late: knows sequence and performance improves but cortical maps go back to baseline. The assumption is that other areas of the brain increase role in task execution
  • Acquisition to Skill: shift toward automaticity
• Reduction in cortical activity
• Increase activation in subcortical centers: basal ganglia, cerebellar nuclei, thalamus

Clinical Application of principles of neuroplasticity

• Kleim and Jones identify criteria for experience-dependent plasticity:
  • Use it or lose it.
  • Use it and improve it.
  • Specificity in challenging the patient.
  • Repetition matters to induce change through practice.
  • Intensity matters to challenge the patient physically.
  • Time matters, specifically the timing of feedback.
  • Salience matters, as the patient's desire to do it is important.
  • Age matters, with children demonstrating more neuroplasticity.
  • Transference, as exemplified by backhand in tennis.
  • Interference from opposing actions.

Motor Learning Feedback Practice

• Feedback is essential for learning.

Intrinsic

• Intrinsic (inherent) feedback comes from all sensory information within the body.

Extrinsic

• Extrinsic (augmented) feedback is information provided by someone externally.
  • Systems that signal Intrinsic feedback
  • Sensory, visual, vestibular
  • Concurrent feedback occurs as the individual performs the movement or task, providing real-time corrections.
  • Terminal feedback occurs after the individual performs the movement or task.

Precision of Feedback

• Qualitative feedback indicates whether the performance was right or wrong.
• Quantitative feedback provides information on the direction and magnitude of error.
• Bandwidth feedback is provided only when performance is outside a specified criteria range to encourage self-correction.

Feedback Scheduling

• Constant feedback is provided on every trial.
• Summed feedback is provided after several trials.
• Delayed feedback is provided after an interval following the completion of a task.
• Fading feedback involves decreasing feedback frequency as the skill level increases.
• Self-control of feedback involves the learner determining when they want feedback.
  • Requires mental processing of error detection and correction; as self-evaluation of need for feedback

Types of Augmented Feedback

• Knowledge of results (KR) provides terminal feedback about the outcome, relating to movement pattern to achieve goal.
• Beneficial to expert learner → self-controlled video of performance.
• • individuals with constant feedback become reliant → Winstein and Schmidt (1990)

Scheduling feedback

• Complex tasks need frequent feedback to improve performance
• Simple tasks may require less frequent feedback

Types of learners

• Adults - appreciate quantitative and precise info
• Kids - unfamiliar quantification units → may be confusing

Environmental Constraints on Movement

• Regulatory features are those in the environment that shape movement patterns
  • Example: height of chair, backpacks, shape or size of object, stable seat
• Non-regulatory features are in the environment that movement does not conform to
  • Example: noise in a room, light in a room, temp of room

Task Variability

• Open tasks change between execution, with an unpredictable environment.
• Closed tasks have no variability between execution and a predictable environment.

Mental practice can be beneficial.

• Activating mental areas will strengthen physical performance → playing piano
• Mental Imagery: imagining performance as either the performer or the observer
  • Internal perspective: what does it feel like?
  • External perspective; what does it look like?
• Mental practice is better than no practice; can supplement physical practice but NOT replace it

Types of Physical Practice

• Simulators - virtual reality, skiing, etc., → goal is to transfer learning to target skill

Part vs Whole

• Part - complex skills with multiple movement segments (serial tasks) → not effective for rapid discrete skills such as pitching but not continuous either such as sprinting/cycling
  • Fractionalization: parts of a skill are practiced (ex: managing wheelchair)
  • Progressive Part: one part is practiced until mastered (A+B...+C)
  • Simplification: simplifying some aspects of targeted skill
• Slow motion - form general movement → slowing down too much can change dynamic of task
• Error detection - focusing on feedback from errors and correct performance → them being able to detect errors on their own
  • Errorless population: dementia and Alzheimer's

Guidance

• Guidance (externally assists an individual through a task (manual, robotic) → can provide correct sensory environment)

Practice

• Massed Practice — practicing without rest intervals
  • For continuous skills: performance suffers, but learning continues → becoming fatigued
  • For discrete skills: learning discrete skills appears better under massed practice conditions
• Distributed Practice: practicing with rest intervals → learning takes place over small increments
• Constant Practice: no variability; same movement pattern & environmental regulatory and non-regulatory
• Variable Practice: variable in each trial, movement pattern changes
  • Examples: golf shot using a 7 iron, basketball free throw

Blocked Practice vs Random — best for retention

• Blocked — repeated trials of one task → repeated trials of 2nd task → repeated trial of 3rd task
  • Results in temporary improvements in performance
• Random — performing different tasks on each successive practice trial in a random order (better for learning)
  • Less learning in retention and transfer

Contextual interference effect

• Contextual interference effect mixing up practice structure; adding different tasks
  • The learner understands distinctiveness of each task; long-term memory of task Used in athletes → game ready