title: Contribution of propriospinal neurons to recovery of hand dexterity after corticospinal tract lesions in monkeys.
abstract: The direct cortico-motoneuronal connection is believed to be essential for the control of dexterous hand movements, such as precision grip in primates. It was reported, however, that even after lesion of the corticospinal tract (CST) at the C4-C5 segment, precision grip largely recovered within 1-3 mo, suggesting that the recovery depends on transmission through intercalated neurons rostral to the lesion, such as the propriospinal neurons (PNs) in the midcervical segments. To obtain direct evidence for the contribution of PNs to recovery after CST lesion, we applied a pathway-selective and reversible blocking method using double viral vectors to the PNs in six monkeys after CST lesions at C4-C5. In four monkeys that showed nearly full or partial recovery, transient blockade of PN transmission after recovery caused partial impairment of precision grip. In the other two monkeys, CST lesions were made under continuous blockade of PN transmission that outlasted the entire period of postoperative observation (3-4.5 mo). In these monkeys, precision grip recovery was not achieved. These results provide evidence for causal contribution of the PNs to recovery of hand dexterity after CST lesions; PN transmission is necessary for promoting the initial stage recovery; however, their contribution is only partial once the recovery is achieved.
authors.affiliation: Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan.|Department of Rehabilitation Medicine, Graduate School of Medicine, Keio University, Tokyo 160-8582, Japan.
authors.forename: Takamichi
authors.initials: T
authors.lastname: Tohyama
authors.affiliation: Department of Physiology, Hirosaki University Graduate School of Medicine, Hirosaki 036-8562, Japan.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Kinoshita
authors.affiliation: Section of Viral Vector Development, National Institute for Physiological Sciences, Okazaki 444-8585, Japan.|The Graduate University for Advanced Studies (SOKENDAI), Hayama 240-0193, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Isa
authors.affiliation: Department of Molecular and System Biology, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Dai
authors.initials: D
authors.lastname: Watanabe
authors.affiliation: Department of Molecular Genetics, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan.
authors.forename: Kazuto
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Department of Rehabilitation Medicine, Graduate School of Medicine, Keio University, Tokyo 160-8582, Japan.
authors.forename: Meigen
authors.initials: M
authors.lastname: Liu
authors.affiliation: Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan; isa.tadashi.7u@kyoto-u.ac.jp.|The Graduate University for Advanced Studies (SOKENDAI), Hayama 240-0193, Japan.|Department of Neuroscience, Graduate School of Medicine and Faculty of Medicine, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Isa
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000235:genetics; D006225:Hand / Q000294:innervation / Q000503:physiopathology; D018737:Hand Strength / Q000502:physiology; D007395:Interneurons / Q000502:physiology; D008251:Macaca; D008297:Male; D009046:Motor Neurons / Q000502:physiology*; D009407:Nerve Block; D009416:Nerve Regeneration / Q000502:physiology; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D009435:Synaptic Transmission / Q000502:physiology
chemical_list: C527701:enhanced cyan fluorescent protein; D049452:Green Fluorescent Proteins
keywords: neural circuit; nonhuman primates; plasticity; spinal cord injury; viral vector