Once our nostrils become free of stuffy summer colds or mould allergy, our brains work overtime to keep our olfactory sense as sharp as ever, compensating for the interruption of this vital sense.
A new Northwestern University Medicine study shows that after the human nose is experimentally blocked for one week, brain activity rapidly changes in olfactory brain regions.
This change suggests the brain is compensating for the interruption of this vital sense. It returns to a normal pattern shortly after free breathing has been restored, the journal Nature Neuroscience reports.
Previous research in animals has suggested that the olfactory system is resistant to perceptual changes following odour deprivation. This new paper focuses on humans to show how that's possible, according to a Northwestern statement.
"You need ongoing sensory input in order for your brain to update smell information," said Keng Nei Wu, graduate student in neuroscience at Northwestern University Feinberg School of Medicine, who led the study.
For the study, Wu completely blocked the nostrils of a group of participants for a week while they lived in a special low-odour hospital room. At night, participants were allowed to breathe normally while they slept in the room.
After the smell deprivation, researchers found an increase in activity in the orbital frontal cortex and a decrease of activity in the piriform cortex, two regions related to the sense of smell.
When unrestricted breathing was restored, people were immediately able to perceive odours. A week after the deprivation experience, the brain's response to odours had returned to pre-experimental levels, indicating that deprivation-caused changes are rapidly reversed.