| 1. |
- Kinoshita, Masaharu, et al.
(author)
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Genetic dissection of the circuit for hand dexterity in primates
- 2012
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 487:7406, s. 235-U1510
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Journal article (peer-reviewed)abstract
- It is generally accepted that the direct connection from the motor cortex to spinal motor neurons is responsible for dexterous hand movements in primates(1-3). However, the role of the 'phylogenetically older' indirect pathways from the motor cortex to motor neurons, mediated by spinal interneurons, remains elusive. Here we used a novel double-infection technique to interrupt the transmission through the propriospinal neurons (PNs)(4-6), which act as a relay of the indirect pathway in macaque monkeys (Macaca fuscata and Macaca mulatta). The PNs were double infected by injection of a highly efficient retrograde gene-transfer vector into their target area and subsequent injection of adeno-associated viral vector at the location of cell somata. This method enabled reversible expression of green fluorescent protein (GFP)-tagged tetanus neurotoxin, thereby permitting the selective and temporal blockade of the motor cortex-PN-motor neuron pathway. This treatment impaired reach and grasp movements, revealing a critical role for the PN-mediated pathway in the control of hand dexterity. Anti-GFP immunohistochemistry visualized the cell bodies and axonal trajectories of the blocked PNs, which confirmed their anatomical connection to motor neurons. This pathway-selective and reversible technique for blocking neural transmission does not depend on cell-specific promoters or transgenic techniques, and is a new and powerful tool for functional dissection in system-level neuroscience studies.
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| 2. |
- Nishimura, Yukio, et al.
(author)
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Time-dependent central compensatory mechanisms of finger dexterity after spinal cord injury.
- 2007
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In: Science (New York, N.Y.). - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 318:5853, s. 1150-5
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Journal article (peer-reviewed)abstract
- Transection of the direct cortico-motoneuronal pathway at the mid-cervical segment of the spinal cord in the macaque monkey results in a transient impairment of finger movements. Finger dexterity recovers within a few months. Combined brain imaging and reversible pharmacological inactivation of motor cortical regions suggest that the recovery involves the bilateral primary motor cortex during the early recovery stage and more extensive regions of the contralesional primary motor cortex and bilateral premotor cortex during the late recovery stage. These changes in the activation pattern of frontal motor-related areas represent an adaptive strategy for functional compensation after spinal cord injury.
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| 3. |
- Yabuta, Hikaru, et al.
(author)
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Macromolecular organic matter in samples of the asteroid (162173) Ryugu
- 2023
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In: Science. - : American Association for the Advancement of Science. - 0036-8075 .- 1095-9203. ; 379:6634
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Journal article (peer-reviewed)abstract
- Samples of the carbonaceous asteroid (162173) Ryugu were collected and brought to Earth by the Hayabusa2 spacecraft. We investigated the macromolecular organic matter in Ryugu samples and found that it contains aromatic and aliphatic carbon, ketone, and carboxyl functional groups. The spectroscopic features of the organic matter are consistent with those in chemically primitive carbonaceous chondrite meteorites that experienced parent-body aqueous alteration (reactions with liquid water). The morphology of the organic carbon includes nanoglobules and diffuse carbon associated with phyllosilicate and carbonate minerals. Deuterium and/or nitrogen-15 enrichments indicate that the organic matter formed in a cold molecular cloud or the presolar nebula. The diversity of the organic matter indicates variable levels of aqueous alteration on Ryugus parent body.
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