The idea of creating a direct connection between a human brain and a computer has a long history in science fiction. The development of brain computer interfaces (BCI), technologies permitting direct communication between a user's brain and an external device, began to become a reality in the 1970s, and have since captured the attention of scientists and the public alike. Initially conceptualized for military use—the initial work was funded by the National Science Foundation and the Defense Advanced Research Projects Agency (DARPA)—more recently BCIs have shown promise for therapeutic uses, providing hope for restorative and even enhanced human capacities.
Utilizing both invasive and non-invasive technologies, scientists are now capable of recording and translating activity from populations of neurons to operate external devices. In early 2013, the technology took a leap forward as researchers replaced the external computer connection with a second embodied brain, dubbing the approach “brain-to-brain” interfacing (BTBI). The direct transfer of information between two brains raises new and important ethical issues. We summarize the first two landmark studies in BTBI research, and then discuss ethical concerns relevant to BTBI as they are applied in clinical, research, and non-therapeutic domains.