Context
We usually consider visual and auditory stimuli as the most dominant sensory inputs in our daily life, yet olfactory stimulus is at least as significant. Olfactory inputs guide us on harmful and attractive odorous sources. It is known that in humans, olfactory input leads to strong emotional affects in terms of attractive and repulsive behaviors (Nicolas et al., 2021). Nevertheless, olfaction remains the least understood of the senses (Philpott et al., 2008). Especially, the link between behavior and odor is strongly investigated in the research.
Nowadays, there is a strong understanding of how our brain codes for different odors through olfactory cells and olfactory receptive fields. Our nose and brain contain more than 400 receptors that can encode for more than 400 000 different odors.
An olfactometer allows controlled delivery of an odor. They can be used in many experiments to see how the brain reacts to an odor for example or how behavior differs depending on odors.
Our Goal
Since research on olfactory stimulations has gained more attention over the years, the demand for olfactometers continues to increase. However, the olfactometers are available for sale don't fulfill the needs of many researchers regarding budget and customization. The prices of olfactometers range from 5000€ to 100.000€, which reduces their accessibility. Additionally, they usually need to go through a customization process depending on the experiment but the complexity of these devices requires specific technical skills. For these reasons, researchers choose to build their own olfactometers in the lab, which can take a lot of time. Consequently, there is currently a need for low-cost, easy-to-build, and portable olfactometers. Our goal is to design an olfactometer that would satisfy these needs, used in behavioral conditioning experiments on mice.
This project was performed for team C4 (Cerebral Codes and Circuits Connectivity) of the Brain Plasticity Unit of ESPCI. This team is interested in neural mechanisms governing memory acquisition and consolidation in mice and how these processes alter brain plasticity.
Conclusion
Our olfactometer device allows reliable, precise, and repeatable odor discrimination tasks in mice. One of the strong suits of this olfactometer is that it can be modulated to the needs of the experiment. New odors can be added by another derivation, a flow meter can be added to control the flow delivered to the mice for more accuracy. In addition to this, this device was built from scratch in 2 months and with a less than 300€.