| Project/Area Number |
15500287
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Neurophysiology and muscle physiology
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| Research Institution | Sapporo Medical University |
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Principal Investigator |
MATSUYAMA Kiyoji Sapporo Medical University School of Medicine, Department of Physiology, Associate Professor, 医学部, 助教授 (40209664)
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| Co-Investigator(Kenkyū-buntansha) |
KOBAYASHI Suguru Sapporo Medical University School of Medicine, Department of Physiology, Assistant, 医学部, 助手 (50325867)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2005: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2004: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2003: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | Rabbit / Hopping movement / Locomotion / Decerebration / Locomotor region / Brainstem / Spinal cord / Descending pathway |
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| Research Abstract |
This study aimed to investigate the neural mechanisms of the control of hopping movements in rabbits. Under halothane anesthesia, male rabbits (2-3 kg) were surgically decerebrated at the precollicular-postmammillary level. The head was then fixed in a stereotaxic apparatus, and the abdominal part was supported by rubber belts. Wood's-metal-filled glass microelectrodes were inserted into the midbrain and electrical stimuli (50 Hz, 10-100 μA, 0.2 ms duration) were applied systematically for 5-15 sec at every 0.5 mm. Stimulus sites for evoking hindlimb hopping were found in the cuneiform nucleus in the midbrain, which corresponds to the mesencephalic locomotor region in cats. During the effective midbrain stimulation, the left and right hindlimbs always exhibited rhythmic movements in phase, not alternately as usually seen in cats' locomotion. Stronger stimuli increased the locomotor cycle frequency and prolonged the emerging period of locomotion. This suggests that although cats and rab
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bits have similar locomotion-inducing sites at the supraspinal level, the neural systems for generating their specific locomotor patterns are organized in a different manner in the spinal cord. After the right spinal cord hemisection at Th11-12, the left or right midbrain stimulation evoked rhythmic movements in the left hindlimb, but no or very weak movements in the right hindlimb. After transection of the bilateral medial longitudinal fasciculus by inserting a thin plastic blade (4 mm wide) into the medulla, the midbrain stimuli at high intensity could still evoke hopping movements. After insertion of a 7 mm-wide blade, however, the stimuli could no longer evoke such movements. These findings suggest that spinal neural circuits for generating in phase left-right hindlimb hopping movements need to receive synchronized bilateral descending inputs from the brainstem, and that the pathways descending in the lateral portion of the reticular formation may function as an important system which mediates locomotor command signals from supraspinal centers to the spinal cord in rabbits. Less
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