The Spinal Cord, Not to Be Forgotten: the Final Common Path for Development, Training and Recovery of Motor Function

Perspectives on Behavior Science, 2018 · DOI: https://doi.org/10.1007/s40614-018-00177-9 · Published: November 13, 2018

Spinal Cord Injury Mental Health Neurology

Simple Explanation

The spinal cord is not just a highway for signals to and from the brain, but can also learn, integrate information, and adapt to experience. This is particularly important after a spinal cord injury (SCI), where the spinal cord's ability to adapt and benefit from training can help recover lost motor functions. Physical therapy can retrain the damaged spinal cord. The understanding of the spinal cord offers a rich opportunity to increase knowledge of the mechanisms of behavior and improve outcomes after SCI. An integrated approach combining behavior analysis, neuroscience, development, and clinical treatment of SCIs is needed to better inform therapeutic treatments and develop a more accurate account of spinal cord and behavioral functioning.

Study Duration

Not specified

Participants

Animal models (rats, cats, mice) and human clinical populations

Evidence Level

Review Article

Key Findings

1
The isolated spinal cord can exhibit classical and instrumental conditioning. Classical conditioning after spinal injury occurs only very soon after injury.
2
Instrumental learning in the spinal cord relies on the induction of long-term potentiation (LTP) and is regulated by glutamatergic receptors. Previous training with contingent shock facilitates learning of limb flexion response and can prevent learning deficits caused by uncontrollable shock.
3
Neonates with SCI show greater sparing and restoration of spinal and motor function compared to adults, referred to as the 'infant lesion effect'. Spinal plasticity has been shown to occur to a greater degree during early development than in adulthood.

Research Summary

Research shows the spinal cord is capable of associative learning, with involvement from the glutamatergic and serotonin systems, and BDNF signaling. Early experience and training shape the developing spinal cord, impacting plasticity and behavioral recovery based on the age of injury. During early development, the spinal cord exhibits heightened plasticity, leading to greater recovery of motor function after injury compared to adults. Motor learning also occurs during development, with the spinal cord adapting to sensory input and showing motor coordination. Clinical interventions for SCI are shifting towards emphasizing recovery through locomotor training, leveraging the spinal cord's plasticity. These interventions, like BWSTT, aim to promote functional use of the intact spinal cord below the lesion, but require task-specific over-ground training for generalization.

Practical Implications

Improved Rehabilitation Strategies

Understanding spinal cord plasticity can lead to more effective rehabilitation interventions that focus on retraining the spinal cord to improve motor function after injury.

Targeted Therapies for SCI

Identifying the mechanisms underlying spinal cord learning can help develop targeted therapies to enhance plasticity and promote recovery of function.

Developmental Considerations in SCI Treatment

Recognizing the differences in spinal cord plasticity between children and adults can lead to age-appropriate interventions that maximize recovery potential.

Study Limitations

1
Differences exist between animal models and humans in response to neurologic injuries, especially regarding spinal shock and spasticity.
2
Lack of evidence-based protocols for clinical manipulation of variables such as weight support and treadmill speed in BWSTT.
3
High cost associated with implementing BWSTT, potentially limiting access to this intervention.

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