Large-scaled network reorganization during recovery from partial spinal cord injury

Abstract

Paralysis of hand movements, especially loss of dexterity, is one of the major problems for the patients suffering from spinal cord injury (SCI) or stroke. The corticospinal tract (CST), especially its direct connection to spinal motoneurons, has been supposed to be the primary pathway involved in the control of hand dexterity. Damage to the CST results in the impairment of hand dexterity. However, it was recently found that if the lateral corticospinal tract (l-CST) was lesioned at the C4–C5 cervical segment, dexterous digit movements showed fairly good recovery within a few weeks to a couple of months in the macaque monkey model. It is suggested that propriospinal neurons in the middle cervical segments are involved in the recovery. By combining multidisciplinary approaches, it was clarified that during the recovery, plastic changes occur in the large-scaled network including not only the spinal cord but also hierarchically higher-order structures such as motor- related cortical areas and even limbic structures. These results suggest that to cure SCI, comprehensive strategies targeting such higher-order structures should be useful in inducing appropriate rewiring of the neural circuits.