Tapping the Mind

Although still largely experimental, devices that decipher brain signals are advancing quickly and allowing some fully paralyzed people to interact with the world. Most of these so-called brain-computer interfaces (BCIs) read the electrical impulses created by neural activity through the scalp, but some scientists are advancing a type of BCI that is implanted inside the brain and taps into the more detailed neural signals relayed by individual neurons. Whether the implanted devices will actually lead to more versatile and workable BCIs than the external type is a matter of fierce debate.