Sribas Chowdhury, Adamas University, Kolkata
Remember that familiar smell of coffee? Or that pizza you had years back? Why is it that no matter how many types of smells we are exposed to, we still retain the memory of some very evident smells? A team of scientists at Washington University set out to find solutions to these very questions. What they found was, according to Professor Branani Raman, “surprisingly simple”. They used locusts for their study, because of their relatively simple anatomy and they’re being used extensively for a lit of previous studies.
Olfaction in locusts:
To understand the mechanism of remembering smells, the team followed the footsteps of Ivan Pavlov’s famous experiment with dogs, which proved that the brain can be conditioned to recognize certain tastes associated with external factors and make relative patterns.
The scientists wondered if there was a similar pattern for remembering smells as well. For this, the locusts were starved and then exposed to an odor (this was called conditioned stimulus), followed by giving them food (called unconditioned stimulus). The food made their mouth open. After this, they were exposed to that same odor again. The mouth opened again, indicating that they had retained the memory of that odor being associated with the reward, food. The locusts could even identify the odor and respond in presence of other odors and conditions like humid and dry atmosphere. The scientists were then curious if this retention follows any neural pattern and so, they resorted to a machine-learning algorithm to find out any possible pattern.
It’s all in neurons:
The team focused on two odorants: hex and iaa. They found out that a subset of peripheral nerves, around 89 of them, was responsible for the locusts’ response to the odorants. In presence of the odorant, the neurons would be activated or turned ON and in their absence, the neurons would get deactivated or turn OFF.
Conclusion:
It was a surprise to the team that such a simple mechanism was acting behind instantly recognizing the odors. The study is interesting in the fact that it highlights one important aspect of the functioning of our neurons: them acting as a switch under simulated conditions. This will definitely help in understanding more complex aspects of neural pathways and how the brain coordinates. The use of machine learning was another big boon as it helped understand how algorithms can be used to predict the working of neurons. This will be especially helpful in future studies on more complex areas of the functioning of the brain.
Also read: Allopathy and AYUSH – The Systems of Medicine in India
Reference:
Nizampatnam, S., Zhang, L., Chandak, R., Li, J., & Raman, B. (2022). Invariant odor recognition with ON–OFF neural ensembles. Proceedings of the National Academy of Sciences, 119(2), e2023340118. https://doi.org/10.1073/pnas.2023340118
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