2005 Fiscal Year Final Research Report Summary
Cortical and basal-ganglia mechanisms related to the control of bipedal locomotion in a freely-moving monkey
| Project/Area Number |
16500271
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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 | Kinki University |
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Principal Investigator |
NAKAJIMA Katsumi Kinki University, Schl.of Med., Lecturer, 医学部, 講師 (60270485)
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| Co-Investigator(Kenkyū-buntansha) |
INASE Masahiko Kinki University, Schl.of Med., Professor, 医学部, 教授 (80249961)
CHIBA Atsushi Kinki University, Schl.of Med., Research Assistant, 医学部, 助手 (30155311)
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| Project Period (FY) |
2004 – 2005
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| Keywords | locomotion / monkeys / cerebral cortex / basal ganglia / primary motor cortex / treadmill / muscimol / single-unit recording |
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| Research Abstract |
We have shown that the Japanese monkey (M.fuscata) could be operant-conditioned to walk quadrupedally or bipedally on the surface of a moving treadmill belt. To further our understanding of cortical mechanisms related to the control of primate locomotion, we first inactivated primary motor cortex (M1), supplementary motor area (SMA) and dorsal premotor area (PMd) of the monkey. We then recorded neuronal activity in M1 and PMd during the execution of locomotor movements on the treadmill.
In the inactivation study, we injected GABA_A agonist, muscimol, selectively into trunk and/or hindlimb regions of M1, SMA and PMd. We found that unilateral injections into M1 produced flaccid paresis in rather restricted part of the hindlimb contralateral to the injection side, resulting in claudication. The most pronounced effect was the foot-drop-like impairment following injections into the digit and ankle regions. Bilateral injections into SMA produced a general reduction of postural muscle tone in
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the trunk and hindlimbs, yielding a tottering gait pattern. Bilateral injections into PMd impaired the initiation of locomotor movements in response to the presentation of food rewards. In the single-unit recording study, tungsten microelectrodes were inserted into hindlimb region of M1 and PMd using a custom-made micro-manipulator. We found that all neurons recorded in M1 modulated their discharge phasically time-locked to the step cycle or increased their discharge frequency tonically during locomotion. The neuron exhibiting phasic modulation peaked once or twice per step. Most of them increased their discharge frequency as the treadmill speed increased. In PMd, many recorded neurons increased their discharge frequency tonically around the initiation of locomotion.
These results demonstrate that cortical motor areas of the monkey contribute in a different manner to the elaboration and control of locomotion, and suggest that M1 contributes to the step-by-step adjustments of the trunk and hindlimb movements, SMA contributes to the moment-to-moment adjustments of accompanying posture, and PMd contributes to the initiation of locomotion. Less
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Research Products
(16 results)
