THAT'S THE WHY:THE SMELL of a peat fire instantly brings me back three decades to happy summer holidays spent running around Mweenish Island near Carna in Co Galway.
A donkey’s bray or a picture of rugged Connemara landscape also reminds me of those childhood adventures, but why is it that a particular scent can route us immediately down memory lane?
While we often overlook our sense of smell, for mammals it is one of the most important – alerting the presence of poisons, predators or potential mates – and humans can detect about 10,000 distinct odours.
Cells with odour receptors sit at the top of your nasal cavity and you detect smells when odour molecules enter your nose and stimulate or inhibit those receptors. Messages are then relayed along the olfactory nerve to the olfactory bulb in a part of the brain known as the “limbic system”, which is associated with emotions.
It’s thought that you link scents with particular events, items, places or people, and it’s this conditioned response that evokes such powerful memories when you smell that odour again even decades later.
A study published last year looked at how the human brain lights up in such conditioned response memories and found that they seem to be laid down on first exposure to the scent, which could help explain why smells from childhood can be particularly evocative.
– CLAIRE O’CONNELL
