Do you know how brain recognizes odors?

Relationship with Different Odors Encoded by our Brain

Source

Harvard Medical School

Highlights

• The relation between different odors that brain encodes is described for the first time by neuroscientists.
• The mechanism may explain that individuals have a common but personalized experience with smells that may explain how the chemistry of odors into the perception of smell is transformed by the brain.

Background

Smelling is something that we even do without noticing it carefully that we are actually smelling the things around us. With every single sniff, you try to get the idea about what kind of smell is surrounding you without even noticing that your senses are working accordingly. The smelling sense becomes more useful when you are passing by a bakery and you start smelling the delicious food but do you actually know the mechanism that leads us to smell things around us let’s explore.

Olfactory Receptors and Brain

So when you are passing by a bakery with every single whiff you take, a cloud of chemicals comes through the air and you are able to recognize the smell of various things surrounding you. According to scientists smell starts from the backside of the nose in which olfactory epithelium has a great role to play like millions of sensory neurons are present in its strip. The tips of these cells constitute proteins, that are known as the receptors that cohere odor molecules. The receptors function as a lock that needs a key to open it so in that case odor molecules function as a key that can open it. It is known that humans have approximately 450 different types of olfactory receptors. Many different types of odors molecules can replenish each and every receptor. Every single odor molecule has the capacity to open up different forms of receptors. Although it is true that the force produced is different in different model this can provide a better link in between the lock and key order. The problem lies in the fitting of these lock and key structures with one another. Or in other words, we can say that the complexity of receptors and their interactions with odor molecules kind of guides us to find different types of smells. And the main point to notice is that smell is actually not a single chemical that reaches our nose and then with the help of the brain we are able to detect it. It is actually the mixture of various chemicals or gases reaching us via the nose.

Odor Molecule and Receptor: Neural Response

Now when an odor molecule binds to a receptor, it starts an electrical impulse that reaches to the sensory neurons with the help of the olfactory bulb, there is a group of the neuron that is present just behind the olfactory bulb that helps us in recognizing the particular smell, this specific area is called as the piriform cortex. This piriform cortex area has a very important role to play in specifying the particular things smell that we are inhaling. Smell information then reaches to the thalamus. Thalamus could be regarded as that area in the brain that contains all of the sensory information arriving in the brain. Then from thalamus few smell information is sent into the orbitofrontal cortex, where it can be combined later on with the taste information. This all results actually in the sense of production of taste. That implies the sense of taste actually being the combination of all the above-mentioned signals of information.

Memory and Smell

Smell has also a role to play with our memory like you could address to the time when you smell certain food and as you have had that particular food for many times that now you could just tell only by smelling that who has cooked that food. Have you ever wondered that what leads you to discover that who has cooked that specific food even without tasting it, so this happens because of the smell information sent to the hippocampus and amygdala, from the thalamus? Hippocampus and amygdala are considered as the very important areas that are specifically included in the learning and memory function of the brain. This could be regarded as that part of the brain that could give a sense of the difference between various smells in order to recognize a specific smell.

Scientists have already claimed that the brain could differentiate in between thousands of smells that are constantly surrounding us. It is even proved by Leslie Voshall, a scientist with the help of proper experimentation that the human brain could differentiate in between 1 trillion different sort of smells surrounding humans. According to Leslie Voshall, one trillion marks is probably an underestimation of the true number of smell a human brain could detect because there are much more than only 128 different forms of odor molecules in the world.

References

• Stan L. Pashkovski, Giuliano Iurilli, David Brann, Daniel Chicharro, Kristen Drummey, Kevin Franks, Stefano Panzeri, Sandeep Robert Datta. Structure and flexibility in cortical representations of odour space. Nature, 2020; DOI: 10.1038/s41586-020-2451-1
• https://www.brainfacts.org/thinking-sensing-and-behaving/smell/2015/making-sense-of-scents-smell-and-the-brain
• https://www.sciencemarg.org/news/2014/03/human-nose-can-detect-trillion-smellls
• https://www.theweek.in/news/sci-tech/2020/06/29/scientists-decode-how-the-brain-recognises-specific-smells.html