You walk into the living room and smell a combination of gingerbread cookies in the oven and eggnog mom has ready for you on the kitchen table - Christmas!

But what if these wonderful holiday scents meant annoying relatives combined with noisy destructive cousins running around the whole house all day. Not so heavenly anymore.

Just like this, researchers have found that fruit flies have a similar method of forming positive and/or negative memories about certain odors.

Researchers Annie Handler and Vanessa Ruta have found that the timing of when the positive or negative response comes has a big impact on whether the fruit flies become attracted or repelled to it.

In order to study the fruit flies, they used a method called optogenetics which is used to control brain activity with light.

They used this method to control when the positive feedback was given in response to an originally neutral odor and saw if the fruit flies developed a positive or negative association with it.

After they found that the timing is crucial in memory association for fruit flies, they further experimented to see what parts of the brain are involved and how the flies know the timing of when the odor and response occurs.

By monitoring changes in the region of a brain called the mushroom body, Handler and Ruta tracked the strength of the connection of cells in the mushroom body to find that the weaker the connection was, the more attracted the animal was to the smell while the stronger the connection, the more neutral or negative the association became.

While analyzing these reactions, the researchers found that there was a signaling pathway in the mushroom body that could control the strength of the reaction depending on the timing.

This showed that memories in fruit flies, just as it is in humans, were dynamic and as fast as it could make positive associations with a stimulus, it could quickly become negative based on another experience it has.

So, the next time you smell the spices and wonderful food of the holidays, remember that this response comes from the countless beautiful and joyful holidays you have spent with your family.

<Sophia Lee Buford High School 10th Grade>