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Remembrance of smells past: how the brain stores those meaningful memories

27.05.2004

Smells trigger memories but can memories trigger smell, and what does this imply for the way memories are stored? A UCL study of the smell gateway in the brain has found that the memory of an event is scattered across sensory parts of the brain, suggesting that advertising aimed at triggering memories of golden beaches and soft sand could well enhance your desire to book a seaside holiday.

By reversing the premise used in Marcel Proust’s Remembrance of Things Past, UCL researchers established that the memory of an event is spread across different areas of the brain such as the hippocampus and the olfactory cortex - the smell gateway of the brain.

In Proust’s story, protagonist Charles Swann is transported back to his childhood when the smell of a biscuit dipped in tea triggers memories from his past.

Dr Jay Gottfried and colleagues at UCL’s Institute of Neurology set up an experiment to establish whether this mechanism could be reversed, i.e. that memories would reawaken the smell-sensitive regions of the brain. The study is published in the latest issue of Neuron.

A group of volunteers was asked to create stories or links between pictures of objects and various different smells. When the volunteers were later shown pictures of the same objects, their piriform (olfactory) cortex was re-activated even though the smell was no longer present.

Dr Jay Gottfried explains: “Our study suggests that, rather than clumping together the sights, sounds and smells of a memory into one bit of the brain, the memory is distributed across different areas and can be re-awakened through just one of our sensory channels. This mechanism would allow human beings more flexibility in retrieving their memories.”

“For example, let’s say you spent an enjoyable evening in a nice restaurant and ate a delicious steak. Now, if the memory of this evening was packaged into a single area of the brain, then major aspects of the original evening might have to be recreated to reactivate the memory successfully.”

“But if the individual aspects of the evening, such as the music playing in the restaurant, the candles on the table and the taste of the steak were stored in different sensory parts of brain, then the whole memory could come back to you through just one of your senses being re-awakened.”

“In an extreme case such as a survival situation, by creating memory associations you would learn to anticipate the pounce of a predator from a number of sensory cues – a pattern of footprints in the sand, a rustling of a bush, or a musky scent in the wind – even if you couldn’t see it.”

“Advertising relies on the fact that memories are a set of associations rather than unitary chunks, where a picture of woman drinking a cocktail on a beach can stir up your own holiday memories, even if the only similarity between the image and your memory is the sun hat she is wearing.”

“That sun hat can set off your own memories of feeling the sand between your toes, hearing the crash of waves, and smelling the pungent aroma of seaweed.”