Gamers help researchers map neurons

The video tutorial discusses a research project where over 3000 neural cells are digitized into a museum. Players trace ganglion cells from a mouse's eye by coloring 10 million 3D cubes, each 4.5 microns across. A 10 by 10 block of these cubes is as wide as a human hair. The mapped cells are verified by up to 25 gamers before being added to the iWire Museum.

What structures were players tracing out in the research project?

Describe the role of gamers in the neural mapping project.