Paralysis: primates recover better than rodents

26. Monkeys and humans exhibit greater motor recovery than rats after similar spinal cord injury, according to a study conducted in Grégoire Courtine's lab at EPFL. Spontaneous improvement occurs during the first six months after a spinal cord injury, allowing a hemiplegic patient to recover partial motor control. The researchers are using this observation to improve clinical trials and patient therapies. The neuronal mechanisms underlying this extensive recovery in primates are nearly absent in laboratory rats, according to the EPFL researchers. "Research on rats is essential for developing regenerative therapies," said Dr. Courtine, "but rodents show fundamental differences from primates in terms of neuronal reorganization and functional recovery." The reason for this lies in differences in anatomy and function of the corticospinal tract, which are the fibers through which the cortex communicates with the spinal cord. In rats, the corticospinal tract is mainly located in the dorsal column and is restricted to one side of the spinal cord, whereas in monkeys and humans this pathway migrated to the lateral column, expand in size, and became bilateral.