Tech companies are always trying out new ways for people to interact with computers-consider efforts like Google Glass, the Apple Watch, and Amazon's Alexa. You've probably used at least one. But the most radical option has been tried by fewer than 100 people on Earth-those who have lived for months or years with implanted brain-computer...

This is today's edition ofThe Download,our weekday newsletter that provides a daily dose of what's going on in the world of technology. Brain-computer interfaces face a critical test Brain computer interfaces (BCIs) are electrodes put in paralyzed people's brains so they can use imagined movements to send commands from their neurons through a wire, or...