1994 Fiscal Year Final Research Report Summary
Analysis of circadian rhythms of optic lobe visual interneurons in the cricket.
| Project/Area Number |
05640770
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
動物生理・代謝
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| Research Institution | YAMAGUCHI UNIVERSITY |
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Principal Investigator |
TOMIOKA Kenji Yamaguchi University, Department of Biology, Associate Professor, 理学部, 助教授 (30136163)
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| Co-Investigator(Kenkyū-buntansha) |
NAGAO Takashi Kanazawa Institute of Technology, Associate Professor, 工学部, 助教授 (70113595)
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| Project Period (FY) |
1993 – 1994
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| Keywords | Circadian rhythm / Circadian clock / Visual system / Insect / Neuron / Optic lobe |
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| Research Abstract |
The main purpose of this study was to clarify the circadian rhythm of the optic lobe visual interneurons and its neural basis in the cricket Gryllus bimaculatus. During past two years of this research project, we have got the following new findings.
1. We have identified several visual interneurons in the optic lobe suitable for circadian rhythm research by intracellular recording and staining with fluorescent dye. They are the medulla giant interneurons with their somata near the basal medulla, their axons runs toward the contralateral medulla through the brain, and innervate the almost whole area of the contralateral medulla. They were classified into 6 groups according to their receptive filed in the ipsilateral compound eye.
2. We have characterized the ciradian rhythm in some of the medulla giant interneurons. Their light induced response was fluctuate in a circadian manner, peaking during the subjective night, while the peaks of the spontaneous activity differed according to the neuron types : Some has peaks during the subjective night while others has during the subjective day.
3. HPLC-ECD analysis revealed that serotonin content in the optic lobe fluctuates in circadian manner, peaking in the night. The application of exogenous serotonin reduced the sensitivity of the visual interneurons.
These data suggest that the visual system is profoundly regulated by the circadian pacemaker and that serotonin is a possible neurotransmitter involved in the regulation of the sensitivity of the visual interneurons.
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