| Project/Area Number |
15370030
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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 |
Animal physiology/Animal behavior
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
SHIMOZAWA Tateo Hokkaido Univ., Res.Inst.Electronic Sci., Prof., 電子科学研究所, 教授 (10091464)
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| Co-Investigator(Kenkyū-buntansha) |
AONUMA Hitoshi Hokkaido Univ., Res.Inst.Electronic Sci., Assoc.Prof., 電子科学研究所, 助教授 (20333643)
NISHINO Hiroshi Hokkaido Univ., Res.Inst.Electronic Sci., Res.Assoc., 電子科学研究所, 助手 (80332477)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥13,600,000 (Direct Cost: ¥13,600,000)
Fiscal Year 2005: ¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2004: ¥5,000,000 (Direct Cost: ¥5,000,000)
Fiscal Year 2003: ¥5,500,000 (Direct Cost: ¥5,500,000)
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| Keywords | Thermal noise / Summation average / Parallel structure / Measurement of Information / Mechanoreceptor cell / Optical measurement / Insect / Brownian motion / 光計測 / コオロギ / 機械感覚器 / 感覚情報 |
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| Research Abstract |
Why nerves are bundles of a large number of fibers? Is this a simple consequence of multi-cellular organization of metazoan life? This naive question will reaches, in the end, what type of selection pressure the nervous system was adaptive to or gaining a survival value in the evolution? and also what kind of constraints has been tied on the adaptation?
Acquisition of information (i.e. measurement) inevitably requires dissipation of energy (entropy in accurate). Energy cost of information in cricket wind receptor cell was measured as very close to the limit of thermodynamic theory (0.7 kBT Joule/bit). Results revealed by this research are followings.
1) Optical measurement of the Brownian motion of the cricket wind receptor hair revealed the validity of fluctuation-dissipation theorem in living tissue.
2) Cricket sensory cell is sensitive to thermal noise and therefore operates as a very poor informational element because of low signal to noise ratio.
3) The present study confirmed that the principle of summation average, i.e. reliability of mean value depends on inverse square root of sample size, is effective principle in the nervous system where cells are largely stochastic because of thermal noise.
The extremely high sensitivity of living cell to thermal noise is not achieved by evolution, but this is rather constraint retroactively to the beginning of life. Spatio-temporally uneven distribution of resource and harm in living environment act as selection pressure for increase in transmission rate of information. Biological solution by living cells which are tied on the constraint of poor signal to noise ratio is the summation average by parallel transmission.
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