Today’s factismal: You’ve got as many neurons in your retinas as there are people in the USA.
When the lights are dim and the mood is right, look deep in your sweetheart’s eyes and you’ll see something amazing: their retinas! These little patches of neural tissue cover more than 70% of the inside of your eye and contain more than 140 million neurons in each retina – that means that you’ve got a neuron for every man, woman, and child in the USA! (But please don’t give your retinal neurons away – you’ll need them to read the rest of the article!)
These neurons are used to gather light and convert it to electrical signals that are passed directly to your brain. As a result, your retinas are the only part of your central nervous system that can be seen without peeling away skin and bone! And that is why doctors shine bright lights into your eyes during exams; they are checking on the health of your central nervous system. But even though we’ve seen retinas since the time of the Greeks, we still have a lot to learn about them.
And that’s where you come in. The folks at MIT have created a game called EyeWire, where you compete with other players to map out neurons in the retina. Whoever does the best job of mapping the neuron gets the highest score and bragging rights. If you’d like to play along, then look at their website: