BCI also brings with it new problems. In “Securing the Exocortex: A Twenty-First Century Cybernetics Challenge,” Tamara Bonaci and her colleagues present an information-theoretic framework to address brain spyware—BCI-enabled malicious applications that extract sensitive information about an individual,including passwords and PINs, from neural signals.6 Issues of security and privacy will become even more critical when BCI applications begin to run on the Web.