1999 Fiscal Year Final Research Report Summary
Anatomical and physiological studies of mushroom body neurons of an insect.
| Project/Area Number |
09640800
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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 |
動物生理・代謝
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
MIZUNAMI Makoto Hokkaido Univ., Res. Inst. for Electronic Sci., Assoc. Prof., 電子科学研究所, 助教授 (30174030)
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| Co-Investigator(Kenkyū-buntansha) |
NISHINO Hiroshi Hokkaido Univ., Res. Inst. For Electronic Sci., Postdoc., 電子科学研究所, 非常勤研究員
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| Project Period (FY) |
1997 – 1999
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| Keywords | insect / mushroom body / associative memory / motor control / olfactory learning / multimodal integration / cockroach / cricket |
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| Research Abstract |
The mushroom body (MB) is a conspicuous neuropil structure in the insect brain, and is critical to various forms of associative memory. In the present study,
1. Activities of MB output neurons of freely behaving cockroaches, Periplaneta americana, were examined. Insulated copper wires of 14-20 μm in diameter were implanted chronically into the MB output neuropil, and unit activity was differentially recorded while the cockroach walked freely in an arena. After the recording, copper ions were impregnated by passing a positive current to mark the location of electrode tips. The 41 units recorded in the present study were classified into (1 ) sensory neurons which responded to visual, olfactory and/or tactile stimuli, (2) motor-related neurons which were active during locomotion, (3) sensory-motor neurons which were active during sensory stimulation and also during motor action. Some motor-related neurons exhibited activity preceding the initiation of specific locomotory action for 0.2-1 sec. These results suggest that the MB integrate various sensory and motor signals and form preparatory signals for voluntary locomotory actions.
2. Dendritic morphology of output neurons of cockroach MB was studied by means of Golgi stainings and by injecting Lucifer Yellow into the neurons. Some neurons had dendrites which interact only with a specific combination of modular subunits of the MBs.
3. The ability of cockroaches and crickets (Glyllus bimaculatus) to associate peppermint with reward and vanilla with non-reward was examined. In both insects, a single trial was sufficient to change the initial odor preference, and memory formed by three-time training retained for at least seven days. The results showed that both species have excellent ability to learn odors and are suited as materials to study neural basis of olfactory learning in insects.
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