Principles of Experience-Dependent Neural Plasticity by Kleim and Jones 2008

Original Editor - Stacy Schiurring

Top Contributors - Stacy Schiurring and Tarina van der Stockt  

This page is a summary of the 2008 article by Kleim and Jones regarding brain plasticity and its application to rehabilitation practice.

Title

Principles of Experience-Dependent Neural Plasticity: Implications for Rehabilitation After Brain Damage

Authors

• Jeffery A. Kleim
  • McKnight Brain Institute, University of Florida, Gainesville
  • Brain Rehabilitation Research Center, Malcom Randall VA Hospital, Gainesville
• Theresa A. Jones
  • University of Texas at Austin

Keywords

• Rehabilitation
• Recovery
• Plasticity

Citation

Kleim JA, Jones TA. Principles of Experience-Dependent Neural Plasticity: Implications for Rehabilitation After Brain Damage. Journal of Speech, Language, and Hearing Research. 2008 Feb;51:S225-39.

Article Summary Part 1: Relearning After Brain Damage

Part 1 discusses how neuroscience research into neuroplasticity can inform rehabilitation strategies for individuals with brain damage. Understanding the principles of neural plasticity offers hope for optimising rehabilitation after brain damage. By using learning as a tool for brain recovery, alongside other therapies, the brain can reorganise itself and potentially regain lost functions.

Key Points

• Neural Plasticity and Functional Recovery
  • The brain has an extraordinary capacity to adapt and reorganize following injury, a process driven by neural plasticity. This plasticity is central not only to learning new behaviours but also to recovering lost functions after brain damage.
  • Even in the absence of formal rehabilitation, brain damage prompts individuals to develop compensatory behaviours—self-taught strategies to navigate daily activities despite lost function. While these behaviours may be adaptive, they can also interfere with rehabilitative efforts that focus on improving the impaired function.
• Learning as a Mechanism for Brain Recovery
  • Learning plays a critical role in the brain's ability to recover from damage. When new learning occurs, it leads to changes in the brain's structure and function, promoting neural growth and reorganisation.
• Challenges of Translating Animal Research to Human Treatment
  • While research on animals has shown that brain injury leads to both neurodegenerative (tissue loss) and neuroplastic (connection reorganization) changes, these findings do not directly translate into specific therapies for humans.
  • Brain injury also alters the brain's response to learning, affecting the excitability of neurons and their ability to form new connections. These changes complicate how learning is processed in the damaged brain, leading to both impairments and potential improvements in learning abilities.

• The Role of Experience-Dependent Plasticity
  • The brain constantly remodels itself based on sensory, behavioural, and cognitive experiences. This experience-dependent plasticity is a critical process for recovery after brain damage.
  • By harnessing this natural capacity for reorganisation, rehabilitation programmes can help promote adaptive changes in the damaged brain. The article highlights the growing interest in using targeted learning strategies alongside other rehabilitation techniques to enhance functional recovery.

• The Importance of Behavioral and Neurobiological Signals
  • Understanding how behavioural and neurobiological signals influence neural recovery is key to optimising rehabilitation strategies. Identifying these signals can guide the development of more effective therapies that support the brain's natural capacity for plasticity and recovery.

• Changes in the Brain Post-Injury
  • Brain damage results in various changes, including: (1) the loss of neural tissue at the injury site, (2) alterations in connected brain regions, and (3) the process of reactive synaptogenesis (formation of new synaptic connections). These changes are part of the brain's attempt to adapt to lost functions.
  • Damage can also disrupt the brain's normal functioning, leading to challenges in learning and recovery. The interplay between neurodegenerative changes and neuroplasticity needs to be understood when designing rehabilitation strategies.

Article Summary Part 2: Principles of Experience-Dependent Neural Plasticity

Part 2 outlines key principles of experience-dependent plasticity that are derived from decades of neuroscience research. While the list is not exhaustive, it highlights important factors that influence rehabilitation outcomes and recovery from brain damage, specifically in how the brain reorganizes itself in response to learning and experience.

Key Principles Likely to Impact Rehabilitation After Brain Damage

1. Use It or Lose It. Neural connections that are not actively used can weaken or be lost over time. This principle underscores the importance of engaging in rehabilitative exercises or tasks to stimulate the affected areas of the brain and prevent further deterioration.
2. Use It and Improve It. Engaging in specific, targeted activities can strengthen neural connections and improve the function of damaged areas. This principle emphasises that repetitive, purposeful activity can enhance neural recovery, particularly when done with increasing difficulty or complexity.
3. Specificity. The brain is more likely to reorganise and form new connections when rehabilitation focuses on specific behaviours or functions. For instance, targeting fine motor skills or speech production after damage to the motor cortex or language centers increases the likelihood of functional recovery.
4. Repetition Matters. The process of neuroplasticity is enhanced through repeated practice. Consistent and frequent training or tasks strengthen the brain's ability to form new neural circuits, especially during the early stages of recovery after brain injury.
5. Intensity Matters. The intensity of rehabilitation is crucial. More intensive therapy, both in terms of frequency and duration, tends to lead to more significant brain changes and functional recovery. This principle suggests that rehabilitation programmes should be demanding and sustained over time for optimal outcomes.
6. Time Matters. The timing of rehabilitation plays an important role in recovery. Early intervention, particularly in the days and weeks following brain injury, is critical for promoting neuroplasticity and preventing maladaptive compensatory behaviours from taking hold.
7. Salience Matters.  The relevance or importance of the rehabilitation task to the individual can enhance brain plasticity. Tasks that are meaningful and engaging for the patient—such as relearning to perform daily activities or regaining communication skills—are more likely to foster successful recovery.
8. Age and Plasticity. The brain’s ability to reorganise and form new connections is influenced by the age of the individual. While the brain remains plastic throughout life, younger brains tend to recover more efficiently after injury. Nonetheless, neuroplasticity continues to play a role in recovery across the lifespan.
9. Transference. This principle refers to the idea that learning in one area can enhance or facilitate recovery in related areas. For example, improving hand strength and dexterity might also help in regaining the ability to use fine motor skills for tasks like writing or typing.
10. Interference. In some cases, new learning or compensatory strategies can interfere with recovery if they are maladaptive or if they reinforce dysfunctional behaviours. For instance, if a patient overcompensates for an impaired limb by relying too much on the unaffected limb, it might hinder the recovery of the impaired side.

Application to the Intact and Damaged Brain

These principles are applicable to both healthy and damaged brains, but their impact is particularly pronounced in the context of rehabilitation after brain injury. After brain damage, the brain's ability to reorganise its neural circuitry—based on experience, learning, and sensory input—can be harnessed to promote recovery. However, specific rehabilitation strategies need to account for how the brain's plasticity operates differently in the damaged brain compared to a healthy one.

Conclusion Statements

The article concludes by reviewing the potential of experience-dependent plasticity as a tool for improving functional outcomes after brain damage. Neuroscience research has provided substantial insight into how the brain can reorganise itself following injury, and these findings suggest that rehabilitative training can play a crucial role in encouraging this reorganisation.

Clinical Take-Home Messages

• Promise of Rehabilitative Training
  • Research strongly supports the idea that rehabilitative training can help improve brain reorganisation and enhance recovery after brain damage. By leveraging the brain's natural plasticity, it is possible to encourage the brain to form new neural connections and regain lost functions.
• Unresolved Challenges in Optimization
  • Despite this optimism, critical issues remain in optimising rehabilitation strategies. Many aspects of how neural reactions to brain damage interact with rehabilitative training, compensatory behaviours, and other treatment methods are still poorly understood.
  • Self-taught compensatory behaviours can either help or hinder recovery, and the impact of age on recovery and plasticity needs further investigation.
• Timing of Intervention
  • Understanding the timing of rehabilitation is essential. There are likely specific "windows" after brain injury during which training can be most effective, and knowing when it is safe and optimal to intervene is crucial for maximising recovery.
• Translational Challenges
  • Translating findings from animal research to human clinical practice remains a complex task, especially for disorders that are difficult to model in animals, such as cognitive and motor speech disorders. Experimental research using human subjects, along with computational models, will be necessary to bridge this gap.
• Collaboration Between Basic and Clinical Research
  • To improve the application of neuroscience research to real-world rehabilitation, there needs to be better collaboration between basic science researchers (who focus on the biological mechanisms of plasticity) and clinical practitioners (who implement rehabilitation therapies). Increased awareness of clinical challenges faced by rehabilitation professionals will help ensure that research addresses the most pressing needs in patient care.