The sweet scent of nostalgia

From school dinners to cut grass, a familiar whiff can transport us back to our childhood in an instant.

And it seems there is some scientific basis to the idea that we can smell memories.Researchers at the Weizmann Institute of Science in Israel, believe they have discovered how scents from the past are so indelibly etched onto our brains.

The study, reported in the journal Current Biology, involved attempting to mimic the creation of childhood memories via smell.

The 16 adult volunteers were shown a picture of an object as they were exposed to a whiff of either pear or fungus.

Ninety minutes later they were shown the same image with the alternative scent.

Scientists then left a week's gap before testing which of the associations was remembered more strongly by exposing the volunteers to the same smells.

The MRA scans used to monitor the participants' brain activity showed the hippocampus region of the brain "light up" in an unusual way when they were exposed to the first smell from the week before. They did not respond in the same way to the second smell.

Dr Yaara Yeshurun explained: "We found that the first pairing or association between an object and a smell had a distinct signature in the brain."

He added that there was something "particularly special" about early memories of smells.

The bad new? Apparently it's easier to remember the unpleasant smells.