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フィロポディアは,成人の新皮質における静かなシナプスの構造的基板である
Dimitra Vardalaki1,2, Kwanghun Chung2,3,4,5,6, Mark T Harnett7,8
1McGovern Institute for Brain Research, MIT, Cambridge, MA, USA.
Nature
|November 30, 2022
まとめ
成人マウスは,神経の可塑性や学習に不可欠な多くの静かなシナプスをフィロポディアに備えています. AMPA受容体が欠けているこれらのシナプスは ヘッビアンの可塑性によって活性化され,成熟した脳で新しい接続を可能にします.
科学分野:
- 神経科学
- シナプスの可塑性
- 分子生物学
背景:
- 哺乳類の皮質に新たに形成された刺激シナプスは,AMPA受容体が不十分であるため,機能的に沈黙していることが多い.
- 静かなシナプスは 神経回路の発達に不可欠ですが 成人の脳では珍しいと考えられていました
- 大人の脳は可塑性を維持し,シナプスの形成と変化が進行していることを示唆しています.
研究 の 目的:
- 成人哺乳類の皮質における静かなシナプスの流行と機能を調査する.
- 成人マウスのシナプス形成と可塑性における dendritic filopodia の役割を調査する.
- 成熟した脳における 固定された機能的な接続性という 確立されたモデルに挑戦すること
主な方法:
- 成人マウスの視覚皮質のピラミッド神経の層5のシナプスタンパク質の超高解像度イメージング.
- AMPA受容体の存在と位置を特定するための2,234のシナプスの分析.
- フィロポディアでシナプス伝達を評価し,可塑性メカニズムをテストする生理学的実験.
主要な成果:
- 大人のマウスのシナプスの約25%がAMPA受容体 (静かなシナプス) を欠いていることが判明しました.
- これらの静かなシナプスは主に以前より豊富に存在する dendritic filopodia に位置していました.
- フィルポディアはNMDA受容体媒介の伝播を示したが,AMPA受容体媒介の伝播はなく,その静かな性質を確認した.
- ヘビの可塑性は これらのシナプスを静止させ ニューロンネットワークに統合することが示されました
結論:
- 大人の皮質にはフィロポディアの静かなシナプスが豊富に存在し,その希少性に関する以前の仮定に異議を唱える.
- この静かなシナプスは 成熟した脳における シナプスの可塑性や学習のための ダイナミックな貯蔵庫です
- この発見は 柔軟なシナプス配線のための新しいメカニズムを明らかにし 大人の神経回路の学習能力を高めています
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