Why Smells From Childhood Mean So Much

Why do certain smells instantly transport you back to childhood? It may be because the first smell you associate with an object is given privileged status in the brain.

Researchers showed volunteers an object such as a chair or pencil that was unlikely to already be associated with a smell at the same time as exposing them to an odor or sound. An hour-and-a-half later, they showed them the same object with a different odor or sound.

One week later, the researchers showed the volunteers the object again and asked them which odor or sound they associated with it, while scanning their brains using functional magnetic resonance imaging. Volunteers were more likely to mention the first odor, and when they did, their brains showed a characteristic pattern of activity in the hippocampus.

Your brain may reserve a special pattern of activity for memories that represent the first time you have associated a smell with a particular thing -- and such pairings are most likely to be laid down in childhood. This ability may have evolved because it enhances the ability to sense danger.

Sources:
New Scientist November 10, 2009

http://blogs.mercola.com/sites/vitalvotes/archive/2009/11/16/Why-Smells-From-Childhood-Mean-So-Much.aspx