Just in time for the holidays, a team of MIT and Max Planck researchers has released EyeWire: an online game that allows users to trace neural connections through the retina.

In the proud tradition of Foldit and other ‘citizen science’ endeavours, EyeWire aims to harness the power of the people to map the projections of retinal cells called JAM-B cells. JAM-B cells respond specifically to upward motion (which appears downward to the retina, because it receives inverted images), and were the first retinal ganglion cells distinguished on the basis of a molecular marker — a protein called junctional adhesion molecule B (JAM-B). Does the downward trajectory of the JAM-B cell projections relate to their function? The scientists behind EyeWire hope to find out.

EyeWire, launched 10 December, is spearheaded by Sebastian Seung of the Massachusetts Institute of Technology (MIT) in Cambridge, who is best known for taking the concept of mapping neural connections and turning it into the surprisingly digestible and well-read popular science book Connectome: How the Brain’s Wiring Makes Us Who We Are. Seung and his colleagues chart the retinal connectome by taking serial electron micrographs of thin slices of tissue. They then trace individual neural projections through each slice and stitch it all together again into a three dimensional image.

Seung’s team could use all the help it can get: in a review of Seung’s book, Christoph Koch, a neuroscientist at the California Institute of Technology in Pasadena, estimated that to map a cubic millimetre of brain would require a billion images and a million working years of analysis time for a trained technician. Computer programs that automatically colour the neuron in each image shorten that time dramatically, but tend to be error prone. Luckily, those errors are often easily spotted by the human eye.

EyeWire players look at the slices and evaluate whether the computer managed to colour in the lines. If the computer stopped colouring too soon, for example, players colour in the neuron manually. The images are from a mouse retina, and are part of a data set described last year in Nature (see ‘Wiring specificity in the direction-selectivity circuit of the retina‘).

Above is an image of JAM-B cell projections mapped since ‘J-Day’ kicked off this morning, courtesy of the Seung lab. EyeWire architects hope that their army of gamers will complete this particular JAM-B cell within a week and be ready to sink their teeth into the next project. Seung says that this approach could be used to understand some forms of blindness and, when applied to other regions of the brain, may shed light on connectivity glitches that he believes contribute to autism.