How does the brain perceive and organize smell? A recent Harvard study shed some light on this little-known area. Published in the journal Nature, the animal study analyzed how different odors are stored in the brain’s olfactory cortex, which is responsible for processing smell. It explored how the brain transforms the chemistry of different odors into its own perception of a smell.
Why does our brain think that lemon and lime smell the same? Photo Credit: Shutterstock
To study how the brain perceived different odors, the team used chemical structure with a known odor profile. These were categorized into three sets of odors. The first set contained a high diversity, the second had intermediate diversity where odors were sub-divided into clusters. Finally, there was the third set which had very little diversity. They then exposed mice to various combinations of the odor. Their brain activity was then studied through images of their neural pathways.
Related odors produced correlated neuronal patterns in both the piriform cortex and olfactory bulb, as measured by overlaps in neuron activity. Weakly related odors, by contrast, produced weakly related activity patterns. The neural connection is also flexible. So, when the mice were exposed repeatedly to two dissimilar odors, their brain formed an association between the two despite the difference in the odor profile.
The brain ‘stores’ smells into categories, which can be rewired according to one’s sensory experience. This may also explain our personalized experience with certain odors while sharing common references for the smell.
