the insights needed to reconstruct effective circuits once axonal regeneration has been achieved.

Animal models allow in-depth investigation of the anatomical and molecular changes that occur in response to a spinal cord injury at a level of detail that would not be possible or ethical in studies with humans. These insights are critical for the design and interpretation of the results of studies with humans. Without the knowledge gleaned from studies with animals, the spinal cord would remain the equivalent of a black box and therapies aimed at restoring function would be limited. For example, experiments with rodents demonstrated that the neurons in the spinal cord are able to regenerate after an injury (Richardson et al., 1980; Xu et al., 1995).

Researchers have developed a variety of animal models that mimic