Neurons Are Not All the Same: Diversity in Neuronal Populations and Their Intrinsic Responses to Spinal Cord Injury

Functional recovery following spinal cord injury will require the regeneration and repair of damaged neuronal pathways. It is well known that the tissue response to injury involves inflammation and the formation of a glial scar at the lesion site, which significantly impairs the capacity for neuronal regeneration and functional recovery. There are initial attempts by both supraspinal and intraspinal neurons to regenerate damaged axons, often influenced by the neighboring tissue pathology. Many experimental therapeutic strategies are targeted to further stimulate the initial axonal regrowth, with little consideration for the diversity of the affected neuronal populations. Neurons are not homogenous but instead exhibit a wide array of diversity in their gene expression, physiology, and intrinsic responses to injury. Understanding this diverse intrinsic response is crucial, as complete functional recovery requires the successful coordinated regeneration and reorganization of various neuron pathways.

• 1
  The neuronal response to injury is variable, based on multiple factors, including the location of the injury with respect to the neuronal cell bodies and the affected neuronal populations.
• 2
  Axotomy sites proximal to the cell body stimulate more successful axonal regrowth compared to lesions further from the soma.
• 3
  Motor recovery is likely achieved through a combination of new axonal regrowth and the establishment of new pathways involving multiple neuronal populations, facilitated by rehabilitative training and reorganization of the motor cortex to accommodate new circuits.