Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
Neuron. 2010 Mar 25;65(6):912-26. doi: 10.1016/j.neuron.2010.02.011.
In mammals, olfactory sensory neurons (OSNs) expressing a specific odorant receptor (OR) gene project with precise stereotypy onto mitral/tufted (M/T) cells in the main olfactory bulb (MOB). It remains challenging to understand how incoming olfactory signals are transformed into outputs of M/T cells. By recording from OSNs expressing mouse I7 receptor and their postsynaptic neurons in the bulb, we found that I7 OSNs and their corresponding M/T cells exhibit similarly selective tuning profiles at low concentrations. Increasing the concentration significantly reduces response selectivity for both OSNs and M/T cells, although the tuning curve of M/T cells remains comparatively narrow. By contrast, interneurons in the MOB are broadly tuned, and blocking GABAergic neurotransmission reduces selectivity of M/T cells at high odorant concentrations. Our results indicate that olfactory information carried by an OR is channeled to its corresponding M/T cells and support the role of lateral inhibition via interneurons in sharpening the tuning of M/T cells.
在哺乳动物中，表达特定气味受体 (OR) 基因的嗅觉感觉神经元 (OSN) 以精确的刻板模式投射到主要嗅觉球 (MOB) 中的僧帽/蒲肯野 (M/T) 细胞上。理解传入的嗅觉信号如何转化为 M/T 细胞的输出仍然具有挑战性。通过记录表达小鼠 I7 受体的 OSN 及其在球内的突触后神经元，我们发现 I7 OSN 和它们对应的 M/T 细胞在低浓度下表现出相似的选择性调谐谱。增加浓度会显著降低 OSN 和 M/T 细胞的反应选择性，尽管 M/T 细胞的调谐曲线仍然相对较窄。相比之下，MOB 中的中间神经元具有广泛的调谐，阻断 GABA 能神经传递会降低高气味浓度下 M/T 细胞的选择性。我们的结果表明，OR 携带的嗅觉信息被引导到其对应的 M/T 细胞，并且支持通过中间神经元进行侧抑制在增强 M/T 细胞调谐中的作用。
