By LEO SANDS Karl Deisseroth, Peter Hegemann and Georg Nagel were awarded the Nobel Prize in physiology or medicine Monday for their discoveries in neuroscience. The three scientists researched light-gated ion channels, a type of proteins, to establish the field of optogenetics, a pioneering technique that uses tiny lights to activate discrete groups of neurons in the brain, said Abdel El Manira, a member of the Nobel Committee that awarded the prize. The discovery has illuminated how…