Introduction

Odor perception can be achieved through ortho or retronasal routes, with the latter being an important component of flavor perception. There are significant olfactory differences that exist between rats and humans and by understanding the role of structural differences, further insight can be gained into the mechanism of odorant perception via ortho or retronasal routes.

Methods

3D human and rat (Sprague–Dawley) computational models were used to investigate nasal anatomy impact on ortho vs. retronasal odorant transport to the olfactory epithelium. The nasal pharynx region was modified for human and rat models to probe nasal structure impact on ortho vs. retro olfaction. Sixty-five odorant absorption rates to the olfactory epithelium were extracted from each model.

Results

The retronasal route provided higher peak odorant absorption compared to orthonasal route for human (left: 90% higher, right: 45% higher), but substantially lowered peak absorption for rat (medial: 97% lower, lateral: 75% lower). For both models, anatomical modification had minimal impact to orthonasal routes, but substantially modulated the retronasal route: decrease (left: − 41.4%, right: − 44.2%) for human, and increase to the medial (29.5%) but not to lateral (− 14.3%) for rat.

Conclusions

There exist key differences between humans and rats regarding retro/orthonasal odorant transport routes, which matched well with experimental olfactory bulb activity data in literature.

Implications

While humans have equivalent odorant delivery between routes, the difference in retro and orthonasal routes in rodents is substantial and changes to the transverse lamina above the nasopharynx can substantially modulate the retronasal route, but not enough to bridge the gap between the two routes.

中文翻译：

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鼻后嗅觉的鼻空气动力学视角：啮齿动物与人类

介绍

气味感知可以通过鼻前或鼻后途径实现，后者是味道感知的重要组成部分。大鼠和人类之间存在显着的嗅觉差异，通过了解结构差异的作用，可以进一步了解通过正鼻或鼻后途径的气味感知机制。

方法

使用 3D 人类和大鼠 (Sprague–Dawley) 计算模型来研究鼻解剖结构对嗅觉上皮的正向与鼻后气味输送的影响。对人和大鼠模型的鼻咽区域进行了修改，以探究鼻结构对正嗅和逆嗅的影响。从每个模型中提取了嗅觉上皮的 65 个气味吸收率。

结果

与人的鼻前途径相比，鼻后途径提供了更高的峰值气味吸收（左：高 90%，右：高 45%），但大鼠的峰值吸收显着降低（内侧：低 97%，外侧：低 75%）。对于这两种模型，解剖学修改对鼻侧路径的影响很小，但显着调节了鼻后路径：人类减少（左：− 41.4％，右：− 44.2％），内侧增加（29.5％）但外侧没有增加(− 14.3%) 对于大鼠。

结论

人类和大鼠之间在逆向/口鼻气味转运途径方面存在关键差异，这与文献中的实验嗅球活动数据非常匹配。

影响

虽然人类在路线之间具有相同的气味传递，但啮齿类动物的鼻后路线和鼻前路线差异很大，鼻咽上方横板的变化可以显着调节鼻后路线，但不足以弥合两条路线之间的差距。