It takes a circuit to develop a mature motoneuron.
It takes a circuit to develop a mature motoneuron.
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DOI：
10.1113/jp280707
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发表时间：
2020-12
期刊：
影响因子：
--
通讯作者：
Heckman CJ
中科院分区：
文献类型：
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作者：
Mahrous AA;Heckman CJ
哺乳动物脊髓含有不同类别的神经元，有助于感觉和运动功能。脊髓神经元通常以独特的背腹侧方式排列，其中参与运动输出的神经元位于腹侧，而背侧神经元介导感觉信号传导。除了直接支配骨骼肌的脊髓运动神经元外，还有 4 种腹侧中间神经元 (V0-V3) 和 6 种背侧中间神经元 (dI1-dI6)，每种类型都有多个亚型。每一类脊髓神经元都是从特定的胚胎祖细胞域发育而来，这一过程严格由精确的遗传程序和局部分泌的信号分子决定（Jessell，2000）。这些不同的神经元群在胚胎发育过程中以惊人的精确度组装，形成脊髓的感觉运动回路。晚熟哺乳动物，如人类、狗、猫和啮齿动物，生来神经系统不成熟，它们的新生儿无法用四肢负重。这些物种的运动行为在出生后继续成熟。尽管脊髓神经元的命运（类型、位置和功能）在胚胎阶段就已确定，但它们在细胞大小、电特性和放电模式方面表现出出生后的变化。然而，目前尚不清楚这种出生后细胞特性的调整是否也是由内在遗传程序编码的，或者是由电路活动和新的突触连接引导的。 Smith 和 Brownstone (2020) 在本期的一篇文章中解决了这个问题。数据表明，回路连接在脊髓运动神经元的出生后成熟中发挥着关键作用。
The mammalian spinal cord contains different classes of neurons that contribute to sensory and motor functions. Spinal neurons are generally arranged in a distinct dorsoventral fashion, where neurons involved in motor output are located within the ventral side, while dorsal neurons mediate sensory signaling. In addition to spinal motoneurons, which directly innervate skeletal muscles, there are 4 types of ventral interneurons (V0-V3) and 6 types of dorsal interneurons (dI1-dI6), with each type having multiple subtypes. Each class of spinal neurons develop from a particular embryonic progenitor domain, a process strictly dictated by precise genetic programs and locally-secreted signal molecules (Jessell, 2000). These various groups of neurons assemble during embryonic development with amazing accuracy to form the sensorimotor circuits of the spinal cord.Altricial mammals, such as humans, dogs, cats and rodents, are born with immature nervous system, and their newborn are not capable of weight-bearing on their limbs. The motor behaviors in these species continue to mature postnatally. Even though the fate (type, location and function) of spinal neurons have been established during embryonic stages, they exhibit postnatal changes in cell size, electrical properties, and firing patterns. However, it is unclear whether this postnatal tuning of cellular properties is also encoded by intrinsic genetic programs, or guided by circuit activity and new synaptic connections. This question is addressed in this issue in an article by Smith and Brownstone (2020). The data suggest that circuit connectivity play a key role in postnatal maturation of spinal motoneurons.