| Project/Area Number |
17500274
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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 | Tottori University |
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Principal Investigator |
MATSUO Satoshi Tottori University, Faculty of Medicine, Assistant Professor, 医学部, 講師 (40219390)
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| Co-Investigator(Kenkyū-buntansha) |
SHIRAISHI Yoshimitsu Tottori University, Faculty of Medicine, Research Associate, 医学部, 助手 (80108810)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2005: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Keywords | Superior Colliculus / Cat / Saccade / Eye-head coordination / Brain stem / Gaze / Saccade / 眼球運動 |
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| Research Abstract |
This study was undertaken to investigate roles of the superior colliculus (SC) and saccade-related premotor areas during gaze saccades in alert cats. The animals were trained to obtain memory guided gaze shifts in darkness. The head is attached to a shaft connected to a friction clutch, which allowed us to immobilize the head for controlled time periods (10 ms-400 ms). A brake immobilized the head shortly after its onset. The eye saccade stopped soon after head velocity declined to zero and, during the ensuing period of head-immobilization, the eye remained immobile in the orbit. The mean time between the onset of the brake-induced head deceleration and when eye velocity became zero (i.e. the onset of the gaze plateau) was 48.5ms ± 19.2ms. Upon brake release the head resumed its movement and an ocular counter-rotation compensated for initial head motion so as to stabilize gaze, resulting in a gaze plateau. After the plateau, a corrective eye saccade was triggered together with head mot
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ion. No corrective saccades, that preceded head-release, were ever seen. Thus, these results showed that cats actually compensated for the brake-induced gaze perturbation.
We first explored the SC's motor map using electrical stimulation. Then, we recorded gaze saccade-related neurons (GSRNs) on the map in the intermediate and deep layers during gaze perturbation. We also recorded the activity of collicular fixation neurons (SCFNs) in the fixation zone of the rostral SC. Activity of both the SC neurons reflected gaze perturbation trajectories, and not related to eye and head velocities. Both the cells encoded gaze-position error which is distance between a target and current gaze position. Axons of GSRNs projected to the ventral part of the abducens nucleus. SCFNs projected to the pontine raphe nucleus where the omnipause neurons (OPNs) were located. A part of the SCFNs have axon collaterals projecting to further caudal areas. Next, we recorded OPNs in the pontine raphe nuclei. Activity of OPNs was higher than SCFNs during gaze fixations. The discharges were related to eye movement during brake-induced gaze plateau. However SCFNs were not related to eye movement. Therefore, these results suggest that activity of OPNs requires additive inputs besides SCFNs. Less
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