Motor training strengthens the GABAergic synapses onto corticospinal tract neurons in the primary motor cortex

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K10710
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 59010:Rehabilitation science-related
• Research Institution: Yamaguchi University
• Principal Investigator: Kida Hiroyuki 山口大学, 大学院医学系研究科, 講師 (70432739)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 運動学習 / 一次運動野 / GABA受容体

Outline of Final Research Achievements

Nerve fibers in the corticospinal tract originate from pyramidal cells in layer V of the motor cortex. To analyze motor learning-induced plasticity at layer V synapses in the primary motor cortex (M1), we trained rats with a rotor rod test. We made acute brain slices of the M1 in untrained, 1-day trained, and 2-days trained rats to evaluate synaptic plasticity. We recorded miniature EPSC and IPSC to evaluate synaptic plasticity in layer V neurons by retrograde tracer in striatum and C4 cervical spinal cord, respectively. Compared to untrained controls, trained rats showed significantly higher miniature IPSC amplitude and frequency, suggesting inhibitory synaptic strength.Thus, the motor-training clearly induced dynamic change in the plasticity at layers V synapses in the M1. Together with the plasticity at layers II/III synapses (Kida et al, 2016), the plasticityin the M1 circuit may contribute to reorganize the control system of pyramidal tract after the motor training.

Free Research Field

神経生理学

Academic Significance and Societal Importance of the Research Achievements

AMPAおよびGABA受容体を介したシナプス可塑性は、記憶・学習などの高次脳機能に関与する。大脳皮質一次運動野 (M1) においては、運動学習後に長期にわたりシナプス伝達効率が上昇することが報告されているが、その神経メカニズムはよく分かっていない。本研究の結果は、運動トレーニング後のV層細胞ではII/III層とは異なる様式のシナプス可塑性が引き起こされることを示唆する。一次運動野V層における錐体路と錐体外路のシナプス可塑性が明らかになった。