| Project/Area Number |
11694091
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
動物生理・代謝
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
TOH Yoshihiro Faculty of Sciences, Kyushu University, Prof., 大学院・理学研究院, 教授 (60037265)
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| Co-Investigator(Kenkyū-buntansha) |
ITO Kei National Insutitute for Basic Biology, Research Ass., 基礎生物学研究所, 助手 (00311192)
TAKAHATA Masakazu Hokkaido Univ., Faculty of Sciences, Prof., 大学院・理学研究科, 教授 (10111147)
ICHIKAWA Toshio Faculty of Sciences, Kyushu University, Ass. Prof., 大学院・理学研究院, 助教授 (50136420)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥7,200,000 (Direct Cost: ¥7,200,000)
Fiscal Year 2001: ¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 2000: ¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1999: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Keywords | tiger beetle / insect / simple eye / stemmata / distance sensitivity / optic lobe / brain / visual interneuron / カマキリ / 複眼 / 距離測定 / 側単眼 / 視覚 / 視覚中枢 / ニューロン回路 / 立体視 / 距離感受性ニューロン / 記憶 / 視覚行動 / 脳の可塑性 |
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| Research Abstract |
The larva of the tiger beetle Cicindela chinensis is an ambushing hunter with a body length of 15-22 mm, that lives in a tunnel in the ground. It ambushes prey, keeping its head horizontal at the opening of the tunnel. When prey approaches the tunnel, the larva jumps to snap at it. When an object moves beyond its jumping range (approximately 15 mm), however, the larva quickly withdraws deep into the tunnel. These responses are mediated by two of six pairs of stemmata. How does the larva judge the hunting range using such a simple visual system? Range estimation by binocular vision was confirmed by behavioral observations, in which larvae jumped towards objects beyond the normal hunting range when virtual images of such distant objects were formed close to the larva by prisms or a narrow window. Range estimation by monocular vision was also confirmed by behavioral experiments. The depth of the image in the retina appears to have a role in distance estimation because a larva with one fun
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ctional stemma, other stemmata being occluded, changed its response to a very distant object from escape to jump when a concave lens was placed above its head.
Intracellular responses of medulla neurons (second order visual interneurons) showed that distance sensitivities really occurred in the peripheral part of the brain. Response patterns of medulla neurons to moving objects at heights of 10 mm and 50 mm were compared. The majority of neurons responded to objects moving at heights of 10 mm and 50 mm with the same discharge pattern. A few neurons, however, showed distance sensitivities responding with an increase of spike discharges to moving objects only at either of the two heights. Such distance sensitivities still remained in one-stemma larvae, three of the four stemmata being occluded.
Above mentioned behavioral and electrophysiological results suggested. We conclude that visual information about hunting range in the tiger beetle larva is extracted peripherally by the spatial pattern of image clarity, and probably centrally by binocular vision. Less
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