Excitatory and inhibitory synapse reorganization immediately after critical sensory experience in a vocal learner.
Excitatory and inhibitory synapse reorganization immediately after critical sensory experience in a vocal learner.
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DOI：
10.7554/elife.37571
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发表时间：
2018-10-25
期刊：
影响因子：
7.7
通讯作者：
Hahnloser RH
中科院分区：
文献类型：
--
作者：
Huang Z;Khaled HG;Kirschmann M;Gobes SM;Hahnloser RH
兴奋性和抑制性突触是大脑中最丰富的突触类型。然而，在运动技能学习的关键时期，当感觉经验定义了动物努力模仿的运动目标时，对它们的形成知之甚少。在鸣禽中，我们发现，暴露于导师的歌声中会导致HVC（这里用作专有名称）中兴奋性突触的消除，HVC是产生歌曲的关键大脑区域。类似的修剪与歌曲的成熟有关，因为幼鸟的兴奋性突触越少，它们的歌曲模仿就越好。相反，辅导是与抑制性突触的快速插入，但辅导引起的兴奋和抑制之间的结构不平衡被消除在随后的歌曲成熟。我们的工作表明，感觉暴露触发的目标特定的运动回路的发展开始，通过增加抑制的相对强度，它表明了一个突触消除模型的歌曲记忆。很多物种都使用复杂的声音来交流，包括人类和像斑胸草雀这样的鸣禽。在学习的关键时期，婴儿和年幼的动物学习如何记住和区分这种“语言”与其他声音。然而，在这个学习期间大脑中发生的变化并没有得到很好的理解。学习过程在大脑神经元之间形成新的连接并修剪掉旧的连接。这些连接，被称为突触，有不同的类型。通过兴奋性突触发送的信号增加了接收神经元的活动，而通过抑制性突触发送的信号减少了神经元的活动。在关键时期，大脑中的突触会发生什么？为了找到答案，黄等人使用电子显微镜检查了从未听过鸟鸣或第一次听到鸟鸣的年轻斑胸草雀的大脑。一天的鸣唱就戏剧性地改变了幼鸟大脑中主要控制声音区域的兴奋性和抑制性突触的平衡。兴奋性突触数目减少，抑制性突触数目增加。兴奋和抑制之间的平衡对大脑正常工作很重要。因此，除了帮助我们了解婴儿如何学习他们的第一语言外，Huang等人提出的结果还可以帮助我们改善这种平衡出错的情况，如情绪障碍。例如，调整药物摄入的时间点与感觉暴露疗法相结合，可以提高任何一种疗法的有效性。
Excitatory and inhibitory synapses are the brain’s most abundant synapse types. However, little is known about their formation during critical periods of motor skill learning, when sensory experience defines a motor target that animals strive to imitate. In songbirds, we find that exposure to tutor song leads to elimination of excitatory synapses in HVC (used here as a proper name), a key song generating brain area. A similar pruning is associated with song maturation, because juvenile birds have fewer excitatory synapses, the better their song imitations. In contrast, tutoring is associated with rapid insertion of inhibitory synapses, but the tutoring-induced structural imbalance between excitation and inhibition is eliminated during subsequent song maturation. Our work suggests that sensory exposure triggers the developmental onset of goal-specific motor circuits by increasing the relative strength of inhibition and it suggests a synapse-elimination model of song memorization. A wide range of species use complex sounds to communicate, including humans and songbirds like zebra finches. During a critical period of learning, infants and young animals learn how to remember and discriminate this ‘language’ from other sounds. However, the changes that happen in the brain during this learning period are not well understood. The process of learning forms new connections between neurons in the brain and prunes away old connections. These connections, known as synapses, come in different types. Signals sent across excitatory synapses increase the activity of the receiving neuron, while signals sent across inhibitory synapses reduce neuron activity. What happens to the synapses in the brain during the critical period? To find out, Huang et al. used electron microscopy to examine the brains of young zebra finches that either had never heard birdsong, or had just heard birdsong for the first time. A single day of hearing song dramatically shifted the balance of excitatory and inhibitory synapses in the main vocal control area of the young birds’ brains. The number of excitatory synapses decreased, and the number of inhibitory synapses increased. The balance between excitation and inhibition is important for the brain to work correctly. Therefore, as well as helping us to understand how infants learn their first language, the results presented by Huang et al. could also help us to improve treatments for conditions where this balance goes wrong, such as mood disorders. For example, tailoring the time point of medication intake in combination with sensory exposure therapies could improve how effectively either one works.