| Project/Area Number |
12834001
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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 Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
TSUDA Ichiro Hokkaido Univ. Grad. School of Sci., Prof., 大学院・理学研究科, 教授 (10207384)
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| Co-Investigator(Kenkyū-buntansha) |
NAMIKI Takao Hokkaido Univ. Grad. School of Sci., Inst., 大学院・理学研究科, 助手 (40271712)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 2001: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 2000: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | hippocampus / episodic memory / chaotic itinerancy / Cantor set / Cantor coding / chaotic dynamical systems / complex systems / θ波 / γ波 / カントールコーディング / カオス |
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| Research Abstract |
It is known that hippocampus works to form series of events that is, episodic memory. We investigate the problem of formation of episodic memory from complex systems point of view. Our purpose is to understand the mechanism of formation of episodic memory leased on high-dimensional dynamical systems theory.
In these two years of the project, we proposed a dynamic model of formation of epicodic memory. Human experience can be explained as a result that consciousness discretises continuous external phenomenon. We set up a hypothesis that gamma wave executes this discretization process. The hippocampus-cortical system synchronizes with theta rhythms with recurrence time in about 200 milliseconds. The discretization of theta wave by gamma wave can be regarded as input series of events to hippocampus. We show that chaotic itinerancy represents the transition of memory, based on the network structures of GA3. Schaeffer collaterals of the pyramidal cells in CA3 send input signal toCA1, which gives rise to a stable dynamical systems, Thus CA3-CA1 system is described as a contracting dynamics driven by chaotic itinerancy.
It is expected that Cantor sets are organized in GA1 region according to a standard theory of contracting maps. We show the existence of such attractors with computer simulations. The chaotic itinerancy in CA3 represents a series of events, namely episode, while the hierarchy of Cantor attractor in CA1 represents a history of chaotic itinerancy. Thus it turns out that Cantor sets implies categories of episode.
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