Remembering in Fruit Flies

This is data from a study about how brains remember important things. Fruit flies are uniquely useful in the field of neuroscience because they grow quickly, have comparatively few neurons, and there are genetic tools to isolate and control individual neuron types.

While fruit flies may seem very different from humans, the way their brains are wired and the mechanisms that their neurons use are quite similar to the brains of other animals, including humans.

Here, I was investigating if certain neurons that are active when flies learn something new are tagged with a molecular signal. I also wanted to know if these neurons need to be active both when a fly is learning and again later on to enable the formation of memories.

Here, I'll explain what these figures show. Each set of bars labeled DAN refers to a different class of neurons that release dopamine.

In the left figure, I found that only two of these classes are active after learning, suggesting that these two are somehow selected for activation. They are possibly tagged with a molecular marker during a learning experience when they are first active.

In the middle figure, I transiently silenced the activity of those same two neurons during learning, and flies could not form long-term memories.

In the right figure, I silenced those two neurons in a time window after learning, and flies also could not form memories. All of this suggests that these two neurons are necessary both during and after an experience worth remembering in order for these memories to stick!