Quantitative assessment of locomotion and interlimb coordination in rats after different spinal cord injuries

Animal models of spinal cord injury (SCI) are intended to mimic the main features of human spinal cord lesions, although sometimes it becomes a difficult task to find the right technique to discriminate the severity of the lesion as well as to assess different aspects of functional recovery. For this reason, we have used several functional methods to assess gross and fine locomotion deficits, as well as electrophysiological data to study the dysfunctions underlying the behavioral changes. Moreover, an extensive study based on the quantification of alternation and coordination parameters during gait has been done. Spinal cord injuries of varying severity (mild contusion, moderate contusion and hemisection) were performed at the thoracic level in adult rats that were followed-up for 6 weeks. Lesions resulting in similar scores in the open field test (i.e. mild contusion and hemisection) caused more marked differences in fine coordination when assessed by quantitative coordination analysis based on a digitized walking treadmill. In conclusion, gross and fine deficits can be detected using a battery of tests based on the performance of the animals during tasks of different difficulty. When used appropriately, they become useful tools to study functional recovery due to spontaneous plastic changes or to therapeutic interventions after SCI, as well as to test the effects of new therapies.