How Does The Timing of Events Affect Learned Associations?

By Susan Wang '22

Would you be happy or sad when you hear the class bell ring? If you’re like me, (let’s be honest with ourselves here), you don’t like the bells ringing that start the classes but love the bells that end them. How so?

A recent discovery helps us answer this question. Fruit flies, probably not very good at thinking, will either like or hate the same smell depending on when they are exposed to it. Researchers discovered this by controlling a “switch” inside flies’ brains. If the switch is turned on immediately before the flies are exposed to a smell, they would hate it. If the switch is turned on immediately after, then they would like it. What’s more interesting is that for the same fly, love-or-hate depends only on the recent exposures. A fly that loves the smell can be turned into one that hates the smell if we keep turning the switch on at the right moment a few times.

Why would flies do that? Researchers have long known that emotions are controlled by the brain and that different types of neurons, the tiny building blocks of the brain, form connections called synapses. We now find out that synapses can have different strengths based on when the flies are exposed to the smell, and the strength decides if the flies like or hate the smell.

https://www.rockefeller.edu/news/26188-learning-experience-timing/