How many electrodes are needed for speech decoding?

What is a brain-computer interface? How can a paralyzed person use her brain to control a robotic arm? How can someone who's lost the gift of speech use brain signals to broadcast his voice again? Can we eventually restore autonomy and dignity so seamlessly that the technology disappears and the person reappears? Where are the ethical boundaries between restoring function and spying on private thought? Who owns the stream of neural data that represents you? Join this week with guest neuroscientist Sergey Stavisky as we dive into the world of interfacing brains and machines.