Plasticity

Training and Plasticity PT 603 Session 3.2

Brain and Behavior

A.k.a The Chicken and the Egg

Copyright 2002 by Mosty Inc

Neuroplasticity

Definition

Neuroplasticity is defined as the brain's ability to adaptively alter its structure or function in response to various stimuli, including developmental maturation, injuries, or shifts in usage patterns. This adaptability is crucial for learning and recovery, enabling the nervous system to remodel in response to experience.

Neuroplastic Changes During Skill Acquisition

Neuroplastic changes are particularly essential when acquiring new skills, as they allow for the brain to adapt and optimize performance. The timeline of these changes can vary significantly based on the complexity of the skill and the training regime. Importantly, neuroplasticity can exhibit a phenomenon known as "Negative Plasticity," where improper training can lead to maladaptive changes in brain structure and function, negatively impacting performance.

Components of Neuroplastic Changes

Physiological Levels

  1. Molecular Level: Involves the upregulation of specific proteins and the modulation of gene expression that contributes to synaptic changes.

  2. Single Neuron Level: Focuses on synaptic plasticity, which is the ability of synapses to strengthen or weaken over time, based on their activity levels.

  3. Network Level: Encompasses alterations in the cortical maps, reflecting the interactions among multiple systems within the Central Nervous System (CNS) that adapt to new learning.

Animal Studies

Research in animal models has provided valuable insights into neuroplasticity. Motor Maps serve as visual representations that evolve with learning, illustrating how the brain reorganizes itself based on experience.

Key Study: Nudo 1996

  • Aim: To demonstrate the brain's intrinsic capacity for change in response to learning.

  • Method: Monkeys were trained on a varied reaching task, during which researchers closely monitored the resulting changes in their motor maps.

Performance with Training

Reaching Task Breakdown

The specific tasks involved intricate motions such as finger extension and flexion. Increased precision was necessitated with the introduction of smaller targets (wells), requiring adaptive movements like flexion and wrist extensions.

Results of Reaching Task

  • Performance metrics showed significant improvements with regular training sessions.

  • Observations indicated a direct correlation between the duration of practice and the number of successful task completions, highlighting the importance of consistency in training.

Observations on Motor Maps

  • Post-training analyses revealed an increase in the areas of motor representation for digits and wrist movements.

  • There were notable discrepancies in performance improvements among different monkey subjects, particularly in those requiring more extensive practice to achieve proficiency.

Importance of Motivation

Motivation plays a dual role in affecting compliance and engaging neurotransmitter systems vital for neuroplasticity, primarily dopamine and norepinephrine. It is essential for sustaining commitment to the training process and optimizing outcomes.

Principles of Skill Acquisition Training

To facilitate effective skill acquisition:

  • Emphasize the necessity for many repetitions to reinforce neural pathways.

  • Implement progressively challenging tasks to adapt to skill improvements.

  • Ensure success is prioritized while maintaining acceptable rates of failure.

  • Foster motivation through rewards and the establishment of meaningful, attainable goals.

Sensory Maps

Sensory maps adapt in response to diverse experiences influencing sensory stimulation. These changes are pivotal in establishing functional efficiency in sensory processing.

Synaptic Plasticity

  • Short-Term Changes: Characterized by the upregulation of neurotransmitters and receptors, requiring minimal protein synthesis, allowing for rapid adjustments in response to experiences.

  • Long-Term Changes: Encompass enduring modifications including structural alterations such as dendritic growth and the formation of new synapses.

Memory Consolidation

Long-term memory is contingent upon physical transformations within the brain, demonstrating the role of neuroplasticity in skill retention and memory.

Mechanisms Driving Neuroplastic Changes

Neuroplastic changes are driven by numerous mechanisms, including:

  • Synaptic activity

  • Second messenger systems

  • Enzymatic activity

  • Gene expression, and

  • Protein synthesis

Kleim et al. 2004 Study

This study illustrated a clear relationship between enhanced motor skills and increased training days, showcasing an increase in synapse counts during later training phases, revealing the cumulative effects of consistent practice.

Implications for Skill Training

Significant changes in motor maps indicate that optimal benefits are seen only with prolonged commitment to practice, suggesting durability in neuroplastic changes requires time and consistent effort.

Sustainable Change in Brain Function

Achieving robust changes in brain function necessitates a commitment to sustained practice, leading to improvements over time.

Comparison of Mechanisms

The study investigates the distinct differences in training modalities for upper extremity skills compared to automatic response patterns, emphasizing the necessity of tailored approaches in training regimens.

Negative Plasticity

Impact on Skill Development

Maladaptive changes from poor practice routines lead to negative plasticity, where repeated errors reinforce incorrect movement patterns. This underscores the need for careful skill acquisition strategies.

Aging and Plasticity

With aging, there is typically a decrease in neuroplastic adaptability and a reduced capacity to respond to new environments due to negative plasticity. However, the potential for reversal exists, suggesting targeted training can counteract some age-related declines.

Neural Mechanisms in Strength Training

Initial Strength Gains

Improvements noted during initial stages of strength training can be attributed to lifestyle changes in neural adaptations rather than immediate physical alterations in muscle tissue.

Motor Unit Changes

  • Higher discharge patterns and increased synchrony among motor units contribute to enhanced strength output.

Structural Changes in Motor Units

Training leads not only to observable increases in strength but also to growth in synapse counts and overall synaptic efficacy.

Motor Neurons Adaptation

Evidence shows significant adaptations in motor neurons, including hypertrophy, increased axonal diameters, and enhancements in myelination, which all contribute to improved performance and recovery.

Conclusion

Initial strength gains from resistive strength training underline the premise that these improvements derive primarily from neural adjustments prior to muscular adaptations.

References

Included key studies and findings relevant to neuroplasticity and motor skill training, serving as foundational literature for further exploration into the implications of this field.