The John B. Pierce Laboratory, New Haven, Connecticut, United States of America.
Department of Neuroscience, Yale School of Medicine, New Haven, Connecticut, United States of America.
PLoS Biol. 2019 Sep 18;17(9):e3000409. doi: 10.1371/journal.pbio.3000409. eCollection 2019 Sep.
The mammalian olfactory bulb (OB) plays an essential role in odor processing during the perception of smell. Optical imaging of the OB has proven to be a key tool in elucidating the spatial odor mapping and temporal dynamics that underlie higher-order odor processing. Much is known about the activation of olfactory sensory neuron (OSN) glomerular responses in the dorsal olfactory bulb (dOB) during odor presentation. However, the dorsal bulb provides access to only approximately 25% of all glomeruli, and little is known about how the lateral bulb functions during this critical process. Here, we report, for the first time, simultaneous measurements of OSN glomerular activity from both the dOB and the lateral olfactory bulb (lOB), thus describing odor-specific spatial mapping and the temporal dynamics of olfactory input to both the dorsal and lateral bulb. Odor responses in the lateral bulb tended to be most prominent in the dorso-lateral (D-L) region. Lateral glomeruli became active in a dorso-ventral (D-V) sequence upon odor inhalation, unlike the anterio-posterior (A-P) activity wave typical of the dorsal glomeruli. Across the entire D-L bulb, the spatial organization of these dynamics can be explained neither by the purely mechanosensitive dynamics (to breathing clean air) nor by the response amplitudes across glomeruli. Instead, these dynamics can be explained by a combination of zonal receptor distributions, associated OB projections, and air flow paths across the epithelium upon inhalation. Remarkably, we also found that a subset of OSN glomeruli in the lOB was highly sensitive to extranasal air pressure changes, a response type that has not been reported in dorsal glomeruli.
哺乳动物的嗅球（OB）在嗅觉感知过程中对气味处理起着至关重要的作用。OB 的光学成像已被证明是阐明空间气味映射和时间动态的关键工具，这些动态是高级嗅觉处理的基础。在气味呈现期间，人们对背侧嗅球（dOB）中嗅觉感觉神经元（OSN）神经球反应的激活了解很多。然而，背侧球仅能接触到所有神经球的大约 25%，并且对于在这个关键过程中侧球的功能知之甚少。在这里，我们首次报告了同时测量 dOB 和侧嗅球（lOB）中 OSN 神经球活动的情况，从而描述了特定气味的空间映射和嗅觉输入到背侧和侧球的时间动态。在侧球中的气味反应倾向于在背外侧（D-L）区域最为突出。与典型的背侧神经球的前后（A-P）活动波不同，在吸入气味时，侧神经球的活动是按背腹（D-V）顺序进行的。在整个 D-L 球中，这些动态的空间组织既不能用纯粹的机械敏感动力学（呼吸清洁空气）来解释，也不能用神经球之间的响应幅度来解释。相反，这些动态可以通过受体的区域分布、相关的 OB 投射以及吸入时空气在鼻上皮上的流动路径的组合来解释。值得注意的是，我们还发现，侧嗅球中的一部分 OSN 神经球对鼻外气压变化非常敏感，这种反应类型在背侧神经球中尚未报道过。
