London: New research explains why a whiff of perfume reminds us of the fun-filled days spent with our grandmother or why the tinkling of a bicycle bell takes us back to the joy of being given our first bike.
Scientists have found that if we smell or hear something while undergoing an emotional experience, the odour or sound is woven together with the emotive memory in the same part of the brain.
Researchers from the National Institute of Neuroscience, Turin, trained rats to associate either a tonal sound, a flashing light or a whiff of vinegar with electric shocks, reports the Daily Mail.
For example, the animals that had seen a flashing light while being given the shock, held the memory of the shock in a brain region that processes visual data.
It is thought the two type of memories are woven together in the grey matters - meaning that retrieving one also triggers the other.
The finding was published in the journal Science.
Previous research has shown that reminiscing can be good for the soul. A British study found that pensioners who got together in groups to talk about their war years or other old experiences and adventures, saw significant improvements in their memory.
Exeter University researchers found just six half-hour chats boosted recall by an average 12 percent - more than what would be expected with any pill.
It is thought that swapping stories about the past in a group makes use of parts of the brain that might otherwise lie dormant.
But our recollections are not always accurate. Scientists believe our memory wears rose-tinted glasses, remembering the good and forgetting the bad.
Studies have found that no matter how badly we have been hurt in the past, we dwell on the positive when thinking back.
It is thought finding the positive side to past failures and tragedies better equips us to face future challenges.
Even happy memories are given the benefit of a rose-coloured tint, with people exaggerating the best moments and down-playing the rest.