V1 interneurons regulate the pattern and frequency of locomotor-like activity in the neonatal mouse spinal cord
V1 interneurons regulate the pattern and frequency of locomotor-like activity in the neonatal mouse spinal cord
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DOI：
10.1371/journal.pbio.3000447
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发表时间：
2019-09-01
期刊：
影响因子：
9.8
通讯作者：
O'Donovan, Michael J.
中科院分区：
文献类型：
--
作者：
Falgairolle, Melanie;O'Donovan, Michael J.
在小鼠脊髓中，V1中间神经元是抑制性脊髓中间神经元的异质性群体，参与调节运动节律的频率和组织屈伸肌交替。通过将古紫质引入增强-1阳性神经元，我们证明了V1神经元在运动样活动中的功能比之前认为的更复杂。在整个脊髓，V1超极化增加了对屈肌和伸肌运动神经元的节律性突触驱动，增加了每个周期的峰电位，减缓了运动性节律。在半脑中，V1超极化在一段时间的紧张性活动后加速了节律，这意味着部分V1神经元在半脑中活跃，钙成像证实了这一点。超极化的V1神经元导致屈肌和伸肌的占空比均衡，而不是对照记录中伸肌爆发长于屈肌爆发的不对称模式。我们的结果表明，V1中间神经元由几个具有不同功能的亚群组成。此外，在V1超极化期间，运动中枢模式发生器(CPG)的默认状态是对称的，每个拮抗性运动神经元都以大约50%的占空比放电。我们假设V1群体的一个功能是设置肌肉的爆发持续时间，使其与其生物力学功能相适应，并适应环境要求，如运动速度的变化。
In the mouse spinal cord, V1 interneurons are a heterogeneous population of inhibitory spinal interneurons that have been implicated in regulating the frequency of the locomotor rhythm and in organizing flexor and extensor alternation. By introducing archaerhodopsin into engrailed-1-positive neurons, we demonstrate that the function of V1 neurons in locomotor-like activity is more complex than previously thought. In the whole cord, V1 hyperpolarization increased the rhythmic synaptic drive to flexor and extensor motoneurons, increased the spiking in each cycle, and slowed the locomotor-like rhythm. In the hemicord, V1 hyperpolarization accelerated the rhythm after an initial period of tonic activity, implying that a subset of V1 neurons are active in the hemicord, which was confirmed by calcium imaging. Hyperpolarizing V1 neurons resulted in an equalization of the duty cycle in flexor and extensors from an asymmetrical pattern in control recordings in which the extensor bursts were longer than the flexor bursts. Our results suggest that V1 interneurons are composed of several subsets with different functional roles. Furthermore, during V1 hyperpolarization, the default state of the locomotor central pattern generator (CPG) is symmetrical, with antagonist motoneurons each firing with an approximately 50% duty cycle. We hypothesize that one function of the V1 population is to set the burst durations of muscles to be appropriate to their biomechanical function and to adapt to the environmental demands, such as changes in locomotor speed.