In the quest to map the brain, many scientists have attempted the incredibly daunting task of recording the activity of each neuron. Optogeneticist Gero Miesenboeck has a different approach for understanding the brain — rather than recording the activity of neurons, he works backwards – manipulating specific neurons to figure out exactly what they do.  In this talk from TEDGlobal 2010, Miesenboeck explains his work manipulating neurons in fruit flies to see what happens when the brain’s code is broken.