Developmental change in synaptic plasticity of corticomotoneuronal direct connections: Do motoneurons learn?

2022 Fiscal Year Final Research Report

• Project/Area Number: 18K06528
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 46030:Function of nervous system-related
• Research Institution: Teikyo University
• Principal Investigator: Ohno Takae 帝京大学, 医学部, 准教授 (60508109)
• Co-Investigator(Kenkyū-buntansha): 福田 諭 帝京大学, 医学部, 助教 (50425641)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Keywords: 運動ニューロン / 皮質運動ニューロン直接結合 / シナプス除去 / 光遺伝学的刺激法 / ホールセル記録

Outline of Final Research Achievements

The developmental time course of the positive ratio and the synaptic strength of cortico-motoneuronal direct connections showed that the direct connections were formed by 1W after birth, reached a plateau at 2W, and then the elimination began and disappeared after 3W. The results were submitted to an English journal (Neuroscience, 2021).
This process of synapse removal was accompanied by the change in the pre-synaptic state due to a change in the paired pulse ratio, but there was no change in the amplitude of the miniture EPSCs, indicating that the post-synaptic state was not involved in the process. Selective knockout of GluN2B from motoneurons partially inhibited synaptic removal, suggesting that GluN2B is involved in this synaptic removal process.

Free Research Field

神経科学

Academic Significance and Societal Importance of the Research Achievements

組織の低酸素化を最大限遅らせ、迅速に脊髄を取り出す独自の手法にて頸髄急性スライスを作成することで、世界的にも困難とされてきた生後３週以降の脊髄運動ニューロンからのホールセル記録を可能にしたことは、運動ニューロンの研究に大きく貢献できるものと考える。また、皮質脊髄路シナプス除去過程ではpresynapseに変化が生じているもpostの関与は明らかでなく、NMDA受容体サブユニットの１つであるGluN2Bを運動ニューロンから選択的にノックアウトすると、シナプス除去が部分的に阻害された事から、本過程にはGluN2Bが関与しており、遺伝的要因に加え、活動依存的な影響も受けていることが示唆された。