title: Reorganization of corticospinal tract fibers after spinal cord injury in adult macaques.
abstract: Previous studies have shown that sprouting of corticospinal tract (CST) fibers after spinal cord injury (SCI) contributes to recovery of motor functions. However, the neuroanatomical mechanism underlying the functional recovery through sprouting CST fibers remains unclear. Here we investigated the pattern of reorganization of CST fibers below the lesion site after SCI in adult macaques. Unilateral lesions were made at the level between the C7 and the C8 segment. The extent of spontaneous recovery of manual dexterity was assessed with a reaching/grasping task. The impaired dexterous manual movements were gradually recovered after SCI. When anterograde tract tracing with biotinylated dextran amine was performed to identify the intraspinal reinnervation of sprouting CST fibers, it was found that the laminar distribution of CST fibers was changed. The sprouting CST fibers extended preferentially into lamia IX where the spinal motor neuron pool was located, to innervate the motor neurons directly. Instead, few, if any, CST fibers were distributed in the dorsal laminae. The present results indicate that CST fibers below the lesion site after SCI in macaques are reorganized in conjunction with the recovery of dexterous manual movements.
authors.affiliation: 1] Systems Neuroscience Section, Primate Research Institute, Kyoto University, Inuyama, Aichi 484-8506, Japan [2] Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakagawa
authors.affiliation: Systems Neuroscience Section, Primate Research Institute, Kyoto University, Inuyama, Aichi 484-8506, Japan.
authors.forename: Taihei
authors.initials: T
authors.lastname: Ninomiya
authors.affiliation: Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: Toshihide
authors.initials: T
authors.lastname: Yamashita
authors.affiliation: Systems Neuroscience Section, Primate Research Institute, Kyoto University, Inuyama, Aichi 484-8506, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Takada
mesh_terms: D000818:Animals; D001132:Arm / Q000503:physiopathology; D008253:Macaca mulatta; D009068:Movement; D009416:Nerve Regeneration; D011712:Pyramidal Tracts / Q000473:pathology / Q000503:physiopathology*; D020127:Recovery of Function; D013119:Spinal Cord Injuries / Q000503:physiopathology*