To understand neuronal information processing, it is essential to investigate the input-output relationship and its modulation via detailed dissections of synaptic transmission between pre- and postsynaptic neurons. In Caenorhabditis elegans, pre-exposure to an odorant for five minutes reduces chemotaxis (early adaptation). AWC sensory neurons and AIY interneurons are crucial for this adaptation; AWC neurons sense volatile odors, and AIY interneurons receive glutamatergic inputs from AWC neurons. However, modulations via early adaptation of the input-output relationship between AWC and AIY are not well characterized. Here we use a variety of fluorescent imaging techniques to show that reduced synaptic-vesicle release without Ca2+ modulation in AWC neurons suppresses the Ca2+ response in AIY neurons via early adaptation. First, early adaptation modulates the Ca2+ response in AIY but not AWC neurons. Adaptation in the Ca2+ signal measured in AIY neurons is caused by adaptation in glutamate release from AWC neurons. Further, we found that a G protein γ-subunit, GPC-1, is related to modulation of glutamate input to AIY. Our results dissect the modulation of the pre- and postsynaptic relationship in vivo based on optical methods, and demonstrate the importance of neurotransmitter-release modulation in presynaptic neurons without Ca2+ modulation.

中文翻译：

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光学解剖的突触可塑性，以早期适应秀丽隐杆线虫。

要了解神经元信息处理，必须通过详细分析突触前和突触后神经元之间的突触传递来研究输入输出关系及其调制。在秀丽隐杆线虫中，预先暴露于气味剂五分钟会降低趋化性（早期适应性）。AWC感觉神经元和AIY中间神经元对于这种适应至关重要。AWC神经元会感觉到挥发性气味，AIY中神经元会从AWC神经元接收谷氨酸能输入。然而，通过AWC和AIY之间的输入-输出关系的早期适应的调制没有很好地表征。在这里，我们使用各种荧光成像技术来显示AWC神经元中没有Ca2 +调节的突触小泡释放减少通过早期适应抑制AIY神经元中的Ca2 +反应。第一，早期适应会调节AIY中的Ca2 +反应，但不会调节AWC神经元。在AIY神经元中测得的Ca2 +信号的适应性是由AWC神经元释放出的谷氨酸引起的。此外，我们发现G蛋白的γ亚基GPC-1与输入AIY的谷氨酸的调节有关。我们的结果基于光学方法剖析了突触前和突触后关系的体内调制，并证明了在没有Ca2 +调节的突触前神经元中神经递质释放调节的重要性。