Can you really smell memories? How childhood scents get 'etched' onto the brain
Scientists have shown that 'odour memories' get 'etched' onto the brain
From the sudden whiff of school cabbage to the pungent smell of hospital disinfectant, nothing transports people back to their childhood more than an unexpected smell.
Now scientists think they have discovered how scents from the past make such a lasting impression.
Using brain scans, they have shown that new 'odour memories' - such as the association of a perfume with a person - really do get 'etched' onto the brain.
The 'signature' of the memory is different from other types of memories, they found.
Dr Yaara Yeshurun, who led the study at the Weizmann Institute of Science in Israel said early smells had a 'privileged' status in our memories.
Scientists have long known that smells are one of the best ways to evoke the past.
Past studies have shown that memories triggered by smells are more vivid and more emotional than those triggered by sounds, pictures or words.
The new study, reported in the journal Current Biology, tried to mimic the creation of childhood memories of smells in 16 adult volunteers.
In a laboratory, the volunteers were shown a picture of an object as they were exposed to a whiff of either a pear or fungus.
Ninety minutes later they were shown the same picture with the other smell.
A week later, the scientists tested which of the associations was remembered more strongly by exposing the volunteers to the same smells.
All the tests were carried out while the volunteers were inside a functional Magnetic Resonance Imaging (fMRI) scanner which monitored brain activity.
Overall, the volunteers found it easier to remember unpleasant smells rather than pleasant ones.
But the MRA scans also showed that part of the hippocampus region of the brain 'lit up' in a peculiar way when the volunteers were exposed to the first smell they had been exposed to the week before.
But their brains did not respond in the same way when the volunteers sniffed the second smell.
The experiment was repeated using sounds rather than smells to see if they had the same impact on memory.
'We found that the first pairing or association between an object and a small had a distinct signature in the brain,' said Dr Yaara.
'This "etching" of initial odour memories in the brain was equal for good and bad smells, yet was unique to odour.'
The researchers also found that they could predict what a person what remember later based on the activity in their brains on the first day.
Dr Yeshurun said it makes good evolutionary sense for people to remember unpleasant memories.
But the findings show that there is something 'particularly special' about early memories of smells, he added.
Smells may trigger such strong memories because our ancestors were more dependent on their noses to avoid poisonous plants, rotten food or enemies than modern people.
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