Jewish World Review

Scientists finding direct links between smell, brain and its emotions | (KRT) You're probably paying more attention to this newspaper with your eyes than with your nose. But lift the paper to your nostrils and inhale.

The smell of newsprint might carry you back to your childhood, when your parents perused the paper on Sunday mornings. Or maybe some other smell takes you back - the scent of your mother's perfume, the mustiness of an old trunk, the pungency of a driftwood campfire.

Specific odors can trigger a flood of memories. Psychologists call it the "Proustian phenomenon," after French novelist Marcel Proust. Near the beginning of the masterpiece "In Search of Lost Time," Proust's narrator dunks a madeleine cookie into a cup of tea - and the scent and taste unleash a torrent of childhood memories for 3,000 pages.

Now, this phenomenon is getting the scientific treatment. Neuroscientists have discovered, for instance, how sensory memories are shared across the brain, with different brain regions remembering the sights, smells, tastes and sounds of a particular experience. Meanwhile, psychologists have demonstrated that memories triggered by smells can be more emotional, as well as more detailed, than memories not related to smells.

When you inhale, odor molecules set brain cells dancing within a region known as the amygdala, a part of the brain that helps control emotion. In contrast, the other senses, such as taste or touch, get routed through other parts of the brain before reaching the amygdala.

The direct link between odors and the amygdala may help explain the emotional potency of smells, scientists say.

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"There is this unique connection between the sense of smell and the part of the brain that processes emotion," says Rachel Herz, a cognitive neuroscientist at Brown University in Providence, R.I.

But the links don't stop there. Like an octopus reaching its tentacles outward, the memory of smells affects other brain regions as well.

In recent experiments, neuroscientists at University College London asked 15 volunteers to look at pictures while smelling unrelated odors. For instance, the subjects might see a photo of a duck paired with the scent of a rose, and then be asked to create a story linking the two.

Brain scans taken at the time revealed that the volunteers' brains were particularly active in a region known as the olfactory cortex, which is known to be involved in processing smells. Five minutes later, the volunteers were shown the duck photo again, but without the rose smell. And in their brains, the olfactory cortex lit up again, the scientists reported recently in Neuron.

The fact that the olfactory cortex became active in the absence of the odor suggests that people's sensory memory of events is spread across different brain regions, says the University College London team leader, Jay Gottfried.

Imagine going on a seaside holiday, he says. The sight of the waves becomes stored in one area, whereas the crash of the surf goes elsewhere and the smell of seaweed in yet a third place.

There could be advantages to having memories spread around the brain. "You can reawaken that memory from any one of the sensory triggers," says Gottfried, "maybe the smell of the sun lotion, or a particular sound from that day, or the sight of a rock formation."

Or - in the case of an early hunter-gatherer out on a plain - the sight of a lion might be enough to trigger the urge to flee, rather than having to wait for the sound of its roar and the stench of its hide to kick in as well.


Remembered smells may also carry extra emotional baggage, says Brown's Herz. Her years of research suggest that memories triggered by odors are more emotional than memories triggered by other cues.

In one recent study, Herz recruited five volunteers who had vivid memories associated with a particular perfume, such as Opium for Women and Juniper Breeze from Bath and Body Works. She took images of the volunteers' brains as they sniffed that perfume and an unrelated perfume without knowing which was which. (They were also shown photos of each perfume bottle.)

Smelling the specified perfume activated the volunteers' brains the most, particularly in the amygdala and in a region called the hippocampus, which helps in memory formation. Herz published the work earlier this year in the journal Neuropsychologia.

But she couldn't be sure that the other senses wouldn't also elicit a strong response. So in another study she compared smells with sounds and pictures.

She had 70 people describe an emotional memory involving three items - popcorn, fresh-cut grass and a campfire. Then they compared the items through sights, sounds and smells. For instance, the person might see a picture of a lawnmower, then sniff the scent of grass and finally listen to the lawnmower's sound. Each person then rated how well the various cues triggered their memory.

Memories triggered by the smell were more evocative than memories triggered by either sights or sounds, Herz reported this spring in the journal Chemical Senses.


Odor-evoked memories may be not only more emotional, but more detailed as well, a pair of British psychologists has argued in a series of papers.

Working with colleague John Downes, psychologist Simon Chu of the University of Liverpool started researching odor and memory partly because of his grandmother's stories about Chinese culture. As generations gathered to share oral histories, she said, they would pass a small pot of spice or incense around; later, when they wanted to remember the story in as much detail as possible, they would pass the same smell around again.

"It kind of fits with a lot of anecdotal evidence on how smells can be really good reminders of past experiences," Chu said.

And scientific research seems to bear out the anecdotes. In one experiment, Chu and Downes asked 42 volunteers to tell a life story, then tested to see whether odors such as coffee and cinnamon could help them remember more detail in the story. They could.


Despite such studies, not everyone is convinced that Proust can be scientifically analyzed. In the June issue of Chemical Senses, Chu and Downes exchanged critiques with renowned perfumer and chemist J. Stephan Jellinek.

Jellinek chided the Liverpool researchers for, among other things, presenting the smells and asking the volunteers to think of memories, rather than seeing what memories were spontaneously evoked by the odors. But there's only so much science can do to test a phenomenon that's inherently different for each person, Chu said.

In the meantime, Jellinek has also been collecting anecdotal accounts of Proustian experiences, hoping to find some common links between the experiences.

"I think there is a case to be made that surprise may be a major aspect of the Proust phenomenon," he says. "That's why people are so struck by these memories."

No one knows whether Proust himself ever experienced such a transcendental moment. But his notions of memory, written as fiction nearly a century ago, continue to inspire scientists of today.



The Sense of Smell Institute is at

A Society for Neuroscience backgrounder on smell and the brain can be found at

A new English translation of "Swann's Way," the first volume of Marcel Proust's "In Search of Lost Time" (also known as "Remembrance of Things Past"), is available from Viking.

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© 2004, The Dallas Morning News Distributed by Knight Ridder/Tribune Information Services