In the olfactory bulb, olfactory information is translated into ensemble representations by mitral/tufted cells, and these representations change dynamically in a context-dependent manner. In particular, odor representations in mitral/tufted cells display pattern separation during odor discrimination learning. Although granule cells provide major inhibitory input to mitral/tufted cells and play an important role in pattern separation and olfactory learning, the dynamics of odor responses in granule cells during odor discrimination learning remain largely unknown. Here, we studied odor responses in granule cells of the olfactory bulb using fiber photometry recordings in awake behaving mice. We found that odors evoked reliable, excitatory responses in the granule cell population. Intriguingly, during odor discrimination learning, odor responses in granule cells exhibited improved separation and contained information about odor value. In conclusion, we show that granule cells in the olfactory bulb display learning-related plasticity, suggesting that they may mediate pattern separation in mitral/tufted cells.

在嗅球中，嗅觉信息由二尖瓣/簇状细胞转换为整体表示，并且这些表示以上下文相关的方式动态变化。特别地，二尖瓣/簇状细胞中的气味表示在气味识别学习期间显示出模式分离。尽管颗粒细胞对二尖瓣/簇状细胞提供主要的抑制输入，并在模式分离和嗅觉学习中发挥重要作用，但在气味识别学习过程中，颗粒细胞中气味反应的动力学仍然未知。在这里，我们研究了清醒行为小鼠中纤维光度法记录的嗅球颗粒细胞中的气味反应。我们发现气味在颗粒细胞群中引起可靠的，兴奋性反应。有趣的是，在气味识别学习中 颗粒细胞中的气味响应表现出改善的分离性，并包含有关气味值的信息。总之，我们表明嗅球中的颗粒细胞显示出与学习相关的可塑性，这表明它们可能介导二尖瓣/簇状细胞中的模式分离。