Remembering in Fruit Flies

Finding the neurons needed to form long-term memories

This data comes from a study of how the brain forms memories. Fruit flies are uniquely useful for this kind of work because they grow quickly, have comparatively few neurons, and come with genetic tools that let us target and control individual neuron types.

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

Here, I asked whether the neurons that fire when a fly learns something new are tagged with a molecular signal. I also wanted to know whether those neurons need to be active twice, both as the fly learns and again afterward, for a memory to form.

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, which suggests they are somehow singled out, perhaps tagged with a molecular marker the first time they fire.

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

In the right figure, I again transiently silenced them, but in a time window after learning, and the flies still could not form long-term memories. All of this suggests that these two classes are needed both during and after a meaningful experience for a long-term memory to form.


I would like to acknowledge and thank K. Keleman, U. Dag, Z. Lei, and I. Siwanowicz for their contributions to project conceptualization, to experimental design, to figure making, for the fruit fly photo, and for their help and support.


Skills

MATLAB · Prism · Experimental design · Data analysis · Scientific figure preparation