Rainbow Coalition

What am I looking at?

This video shows multiple neurons within the brain of an adult fruit fly, progressively stacked on top of each other as the video proceeds. The neurons were visualized using a technique called multicolor flipout (MCFO), which allows researchers to randomly label individual neurons with various colors. Several different preparations of fly brains were individually imaged and registered and then digitally fitted together.

Biology in the background

The role of neurons is to receive, process, and transmit signals. They do this by making connections with other neurons in the nervous system, as well as other cells within the body, and sending them electrical or chemical signals via connection points called synapses. Researchers have long been trying to construct maps of these connections to give them a better understanding of the mechanisms behind this communication. These maps are called connectomes.

Confocal microscopy, the technique used in creating this video, doesn’t offer enough resolution to distinguish and map out all the synapses between neurons, but it does offer a bird’s-eye view of the brain’s neurons. This kind of data is useful as a coarse road map for identifying neurons in the higher-resolution electron microscopy datasets that are used in creating connectomes.

It helps enormously that the structure and connections from one fruit fly brain to another are highly consistent – a characteristic called neural stereotypy. If that weren’t the case, making a comprehensive brain map would be very difficult. Neural stereotypy is a unique feature of insect brains and is one of the reasons the fruit fly is such a useful model organism.

The brain of an adult fruit fly is about 1 millimeter long, or roughly 13 times larger than the width of a human hair.

Technique

This image was created using confocal microscopy.