14 DAY TRIAL // We've all experienced this at least once – smell something and get instantly transported back into our childhood. Strong memories are associated with various smells and situations, a fact which has been known for quite some time. But a new set of studies seems to show that the smells we experience for the first time are given “privileged” status in the brain. This means that we remember them always over other, more recent memories. A region of the brain, known as the hippocampus, is believed to be involved in this process, Israeli researchers have recently established.
In a new set of experiments, scientists from the Weizmann Institute of Science, in Rehovot, Israel, asked volunteers to look at a chair or a pencil – objects that the test subjects were very unlikely to have already associated with other smells – while being exposed to an odor or a sound at the same time. Some 90 minutes later, the same participants were exposed to the same object, but different smells and sounds. They then went home for a week, and returned afterwards for follow-up studies.
The scientists presented all of the participants with the chair or pencil again, and then asked them about the sound or smell that was also present in the room at the time of the first test. In addition , the team looked at their brains during the process, using an observations technique known as functional Magnetic Resonance Imaging (fMRI). The method allows for blood flow patterns to be distinguished inside the brain, essentially telling investigators which areas are activated and which are turned off. The test subjects were very likely to remember the first odor they smelled while looking at the object.
“The evolutionary implication is that the situation in which you first encounter an odor is likely a reliable maker for its meaning, and it is highly adaptive to learn that meaning so that the odor can be responded to appropriately in the future,” Rachel Herz explains. She is a visiting professor at Brown University in Providence, Rhode Island, as well as the author of a book called “The Scent of Desire: Discovering our enigmatic sense of smell.” Details of the investigation appear in the latest issue of the scientific journal Current Biology, NewScientist reports.