| Project/Area Number |
11680743
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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 |
Nerve anatomy/Neuropathology
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| Research Institution | The Institute of Physical and Chemical Research (2000)
Toho University (1999) |
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Principal Investigator |
OJIMA Hisayuki RIKEN, Cortical Organization and Systematics, Senior Scientist, 脳皮質機能構造研究チーム, 上級研究員 (00104539)
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| Co-Investigator(Kenkyū-buntansha) |
KISHI Kiyoshi Toho Univ.Dept.Medicine, Professor, 医学部, 教授 (00014118)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2000: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1999: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | auditory field / axon / convergent projection / tonotopic map / horizontal connection / local circuit / anterograde tracer / cat / 聴覚 / 大脳皮質 / 1次聴覚野 / 局所結合 / 軸索投射 / 聴覚皮質 / 周波数マッピング |
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| Research Abstract |
A small population of cortical neurons project local, short-distance axons. This projection is not diffusely or homogeneously distributed over the cortical region, but forms patches of terminal axons at several hundred μm distant from injection site, in addition to a dense plexus of axons around injection site. How do patchy organizations of terminal axons originating from different cortical sites located closely but representing different sensory features interact each other? Does a particular cortical site receive information only from one cortical site or from multiple other cortical sites? In the latter case, there must take place some convergence of information. Revealing the pattern of cortical convergence seems to be crucial to understanding some basic mechanism of cerebral cortex.
Under aneasthetic condition, the auditory corex of cats were mapped using the conventional electrophysiology by applying pure tones to contralateral ear. Then two tracers, phaseolus vulgaris leukoagglu
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tinin (PHA-L) and biotinylated dextran amine (BDA), were ionotophoretically injected in close proximity, separating at about 500 to 1000 μm. Injection sites covered cortical area of about 300-500 μm in diameter. After cutting tangential sections from the auditory cortex, PHA-L and BDA were reacted for different colors ; purple to black and brown, respectively. Differentially labeled axons originating from different tracer injection sites were scanned for their distribution over the auditory cortex. Areas which contain only one of the two tracer-labeled axons and areas which contain both tracer-labeled axons were identified. Injections into the center part of the primary auditory cortex (Al) resulted in patches of labeled axon distributing medial and lateral to the injection site, while injections into more posteriorly located part resulted in patches distributing more widely, including anterior and posterior in addition to medial and posterior to injection site. In both injection cases, overlapping distribution of PHA-L-labeled axons and BDA-labeled axons was found mainly at the most distal patches medially and laterally. Since a systematic tonotopic map of frequency is formed across cat Al, the results indicate that local circuits related to high-frequency and low-frequency processing take different form of connection. Less
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