How does the sense of smell help us remember things from the past? asks Jose Pestantez, a student in Woodside, NY.
Open a new box of crayons, and your mind is flooded with scenes from the first day of kindergarten. The smell of a snuffed-out candle can evoke memories of birthdays past. And a whiff of the right perfume can bring back times spent with a long-gone grandmother.
More than sight and sound and touch, smell is the sense most linked to both memory and emotion. Scientists say this is probably because scent is so important to survival. Just think of kittens, eyes closed, learning who their mother is by her unique scent. Smelling and remembering smells help animals find edible food and avoid danger.
The brain’s olfactory cortex, which decodes odors received from the nose, is linked closely to the amygdala, the brain’s seat of emotion, and to the hippocampus, where memories are consolidated for storage. Research shows that memories evoked by odors are among the most vivid.
And recent studies show that we can use the smell connection to improve our memories-say, on the morning of a big test. Researchers have known for some time that “sleeping on it” is good advice when it comes to learning, since sleep helps the brain process new memories. So studying and then sleeping may help us remember more the next morning, when faced with that blank answer sheet.
But what if sleeping could be combined with smelling, for a one-two memory punch? Researchers in Germany devised an experiment to find out. Neuroscientists had student volunteers play card-matching games on a computer. As they located pairs of cards, players received a puff of rose-scented air.
Afterwards, the students went to sleep for the night, sporting electrodes that allowed researchers to track their sleep stages. Meanwhile, the scientists sent gusts of rose fragrance to students during different sleep stages. The next morning, those who had inhaled rose-petal scent during deep-sleep stages were much better at remembering the locations of card pairs. The scent-primed group got 97 percent right, versus the scent-free group’s 86 percent average.
To see how the smell/memory connection worked in the brain, the researchers repeated the experiment using an MRI machine. When a student – asleep in the scanner — got a precisely-timed whiff of roses, the MRI revealed activation of the brain’s cortex and hippocampus. In fact, the hippocampus was busier when the students were asleep and smelling roses than when they were awake, trying to recall card locations. The MRI provided a visual picture of the brain connecting the dots of smell and memory.
But we don’t need to stop and smell roses while studying; occasional whiffs of any single strong scent can help. Of course, we won’t have a bedside machine wafting the scent of Cram at us as we fall into a deep slumber. Still, the next morning, we can try bringing the chosen scent with us to the exam – say, by spraying it on our pencil. Studies show that such scent-linking may trigger some handy memories.