tell me what we're hearing. >> andy schwartz: right there, you're hearing the cell fire. >> pelley: theow it works. we just have to figure out the language. schwartz has been decoding that language by watching the monkey's movement and recording the corresponding signals in its brain. so what does that tell you? >> schwartz: so, there's a relationship between how fast the neuron fires and the way the animal moves its hand. and we're trying to understand that relationship, so that if we see a neuron firing, we can say, "ah, the animal's about to make this kind of movement." >> pelley: once schwartz started to figure out that relationship, he was able to connect the monkey's brain directly to a robotic arm. within days, the monkey operated the arm as if it was his own. >> schwartz: the monkey has both arms restrained. and we're recording brain signals from its brain, and it's using those brain signals to operate this entire arm. >> pelley: so he's operating the arm in three dimensions-- up/down, forward and back? >> schwartz: as well as the gripper. >> pelley: what you're telling me is th