Department of Neurosciences and Developmental Biology, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria.
Department of Neurosciences and Developmental Biology, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria.
J Neurosci Methods. 2020 Jul 15;341:108794. doi: 10.1016/j.jneumeth.2020.108794. Epub 2020 May 22.
Concentration is a variable aspect of an odor signal and determines the operation range of olfactory receptor neurons (ORNs). A concentration increase is perceived as an odor stimulus. The role that the rate of concentration increase plays thereby has been studied with electrophysiological techniques in ORNs of the cockroach. A key prerequisite for these studies was the development of an air dilution flow olfactometer that allowed testing the same change in concentration at various rates.
The rate of concentration change was controlled and varied by changing the mixing ratio of odor-saturated and clean air by means of proportional valves. Their input voltages were phase shifted by 180° to hold the mixed air at a particular constant volume flow rate.
Using this stimulation technique, we identified, in a morphologically distinct sensillum on the cockroach's antenna, antagonistically responding ON and OFF ORNs which display a high sensitivity for slow changes in odor concentration.
The olfactometer is unique because it enables delivering slowly oscillating concentration changes. By varying the oscillation period, the individual effects of the instantaneous odor concentration and its rate of change on the ORNs' responses can be determined.
The olfactometer provides a new experimental approach in the study of odor coding and opens the door for improved comparative studies on olfactory systems. It would be important to gain insight into the ORNs' ability to detect the rate of concentration change in other insects that use odors for orientation in different contexts.
浓度是气味信号的一个变量方面，决定了嗅觉受体神经元（ORNs）的工作范围。浓度的增加被感知为气味刺激。因此，已经使用蟑螂 ORNs 的电生理技术研究了浓度增加率的作用。这些研究的一个关键前提是开发一种空气稀释气流嗅觉计，该嗅觉计允许以各种速率测试浓度的相同变化。
通过使用比例阀改变饱和气味空气和清洁空气的混合比来控制和改变浓度变化率。它们的输入电压相差 180°，以保持混合空气以特定的恒定体积流量。
使用这种刺激技术，我们在蟑螂触角上的一个形态上独特的感觉器官中鉴定出了拮抗反应的 ON 和 OFF ORNs，它们对气味浓度的缓慢变化具有高灵敏度。
嗅觉计是独一无二的，因为它能够提供缓慢振荡的浓度变化。通过改变振荡周期，可以确定瞬时气味浓度及其变化率对 ORNs 反应的个别影响。
嗅觉计为气味编码的研究提供了一种新的实验方法，并为嗅觉系统的改进比较研究开辟了道路。了解其他使用气味在不同环境中进行定向的昆虫检测浓度变化率的能力将非常重要。
