Learning to promote recovery after spinal cord injury
Exp Neurol, 2020 · DOI: 10.1016/j.expneurol.2020.113334 · Published: August 1, 2020
Simple Explanation
This article discusses how the principles of learning can be applied to neurorehabilitation after spinal cord injury (SCI). It challenges the traditional view that the adult spinal cord is hardwired and incapable of learning, presenting evidence that neurons within the spinal cord can support learning even after communication with the brain has been disrupted. The article highlights that noxious stimulation can sensitize circuits within the spinal cord, similar to brain-dependent learning and memory. However, after a spinal contusion injury, pain input can worsen the injury and hinder long-term recovery. Conversely, exposure to rhythmic stimulation, treadmill training, and cycling can enhance the expression of brain-derived neurotrophic factor (BDNF) and reduce nociceptive sensitization. Pairing epidural stimulation with activation of motor pathways also promotes recovery after SCI. The authors suggest that a neurofunctionalist approach, which focuses on how specific stimuli and training methods impact spinal function, can be used to develop strategies that promote recovery after SCI.
Key Findings
- 1Spinal cord injury enables plasticity by down-regulating the Cl− co-transporter KCC2, which reduces GABAergic inhibition, enabling learning but also fueling over-excitation and nociceptive sensitization.
- 2Noxious stimulation after spinal cord injury induces sensitization, fosters hemorrhage, and impairs recovery, whereas controllable or predictable stimulation increases BDNF and promotes adaptive plasticity.
- 3Neurorehabilitative strategies that involve relational learning, such as pairing epidural stimulation with cortical stimulation or establishing instrumental relations between muscle activity and spinal stimulation, have a lasting effect.
Research Summary
Practical Implications
Targeting GABAergic Inhibition
Treatments that re-establish GABAergic inhibition could have therapeutic value for reducing chronic pain and spasticity after SCI.
Protecting Against Noxious Input
Attenuating pain soon after injury, possibly through local anesthetics like lidocaine, could improve patient wellbeing and long-term recovery by blocking nociception-induced tissue loss.
Employing Relational Learning
Neurorehabilitation strategies should incorporate relational learning principles, such as pairing stimulation with motor activity, to enhance and prolong treatment effects.
Study Limitations
- 1The review primarily focuses on animal studies, particularly rats, which may not fully translate to human physiology and clinical outcomes.
- 2The review acknowledges that spinal learning is limited compared to brain-dependent learning, especially in terms of flexibility and complexity.
- 3The effectiveness of various interventions, such as BDNF treatment, depends on the stage of injury and the specific circumstances, requiring a nuanced approach.