What is classic conditioning? 

Classic pavlovian conditioning consists in presenting food to an animal coupled with a sound, after some time the animal will react and starts salivation when only the sound is presented. The olfactometer would be used for contionning tasks coupled with odor. Certain odor will be presented with a reward (food) or a fear (foot shock).

What would our system be used for?

To study learning and memory processes. They use conditioning to train mice to associate a reward or a fear with an odor and study the memory of this fear or reward with the odor. It will be used for odor discrimination tasks.

Projects in the C4 team lab at ESPCI integrating our olfactometer:

One of the PHD student in the lab, Maelle Christiaens would use the olfactometer for several types of experiments. The odor would be presented to mice with the olfactometer and either paired with a foot shock or sugar (negative or positive stimulus). This would generate in the mice an associative memory of the odor with a positive or negative thought. Then usually both odors would be presented to the mouse at different locations in the arena and the time the mouse would spend in each compartment would be recorded (See Figure)

Figure 1: Diagram of conditioning experiment using odors. Here, the mouse is associating an odor with a positive or negative memory

On top of that, using a miniscope implanted on the head of the mice, calcium activity at the single-neurone level can be recorded. Looking at single neurone activation in one region allows seeing if some neurones are tuned to a specific odor or to one emotional component.

Another experiment they could perform is to artificially activate a brain region that is associated with an odour to create a positive or a negative association and see if the mouse reacts when confronted to this odor again. The goal would be to see if the mice has an artificial memory of the odor(See figure below).
Finally, a potential application of those behavioural studies would be to activate some brain regions to transform negative memories and reverse them into positive memories. This could be especially ground-breaking in post-traumatic stress disorder (PTSD), where negative emotions are associated with specific triggers. Rewiring the brain to remove those negative associations would help people suffering from PTSD.

Figure 2: Diagram of the experiments using odors in the Vetere lab. Above is looking at which neurones are associated with an emotion and below is stimulating this single neuron with an odor and see if a positive memory is formed

Conclusion

Our olfactometer device allows reliable, precise and repeatable odor discrimination tasks in mice. It will be used by the Vetere lab in many neuroscience experiments involving mice, to study memory formation and processes.