Multi-level analyses for exploring evolutionary origin of excitatory neurons

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H02591
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 46020:Anatomy and histopathology of nervous system-related
• Research Institution: Kyoto Institute of Technology (2023); Kyoto Prefectural University of Medicine (2021-2022)
• Principal Investigator: NOMURA TADASHI 京都工芸繊維大学, 応用生物学系, 教授 (10323007)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 大脳皮質 / 哺乳類 / 興奮性神経細胞 / 羊膜類 / 神経回路 / 進化

Outline of Final Research Achievements

The results of this study confirm that the mechanisms of excitatory neuron development and neural circuit formation that constitute the mammalian cerebral cortex are universally present in amniotes. In particular, we found that the developmental process of the corpus callosum, which exists only in amniotes, also found in reptiles and birds. Furthermore, we identified that Satb2 is involved not only in neuronal differentiation and axonal outgrowth but also in dynamic tissue remodeling, such as fusion between hemispheres. These results suggest that the common ancestor of amniotes had already acquired the developmental program of cortical excitatory neurons, and that this ancestral developmental program was the basis for the formation of mammalian-specific cortical structures and neural circuits.

Free Research Field

神経発生学

Academic Significance and Societal Importance of the Research Achievements

大脳皮質の機能発現に重要な役割を果たす層特異的神経回路が進化の過程で一体いつ出現し、どのような過程を経て現在の哺乳類の皮質投射パターンが完成したのか、その過程にどのような遺伝子の機能が関与していたのか、という問題は、19世紀以降の神経解剖学分野の大きな謎として残されていた。今回の研究成果により、大脳皮質の解剖学的特徴に寄与する発生プログラムの起源と進化に関する興味深い知見を得ることができた。この成果は現在の神経科学の大きなテーマの１つである「ヒトの脳の進化起源」の理解に大きく貢献することが期待される。さらに、脳梁欠損などのヒト先天性疾患の病態理解や早期診断にも重要な知見を提供するものである。