Does the number of targets dominated by each axon depend on the number of competitors?

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K07039
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Neurophysiology / General neuroscience
• Research Institution: Nagoya University
• Principal Investigator: Egawa Ryo 名古屋大学, 医学系研究科, 特任助教 (20722226)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 軸索間競合 / コネクトミクス / 発達期再編 / ニワトリ胚 / 杯状シナプス

Outline of Final Research Achievements

The underlying principles that allow axons to compete with each other to mature their connections to target cells during developmental neural reorganization are still poorly understood. To experimentally test the hypothesis that the number of targets dominated by each axon depend on the number of competitors, we used ciliary ganglion synapses as a model system in which presynaptic connections converge from one-to-many to one-to-one during development. We quantitatively assessed axon projection patterns when the number of presynaptic neurons is genetically thinned out. As a result, halving the number of presynaptic neurons did not change the number of synapses formed by axons, and the number of postsynaptic neurons also decreased. This result suggests that the number of targets dominated by each axon may be destined by endogenous molecular/cellular mechanisms, rather than by the number of competitors.

Free Research Field

神経科学

Academic Significance and Societal Importance of the Research Achievements

発達期における神経回路の再編は、脳の発達の根幹を成す現象の1 つである。学習の臨界期の神経基盤として広く認識されているほか、発達期再編の異常は統合失調症や自閉症、共感覚の原因であるという指摘もされている。本研究で得られた成果は、軸索の標的支配数は競合相手の数ではなく、内因的な分子・細胞メカニズムによって運命づけられている可能性を示唆し、今後のさらなる研究の発展が期待される。