Many engineering and scientific challenges have to be overcome before deployment. Foremost, the physics of scattering and wavering of signals as they travel to brain tissue. They obviously need to be right on target. If that is accomplished, researchers must develop algorithms for coding and decoding neural signals. Then, animal testing must be performed to determine safety. And, finally, human volunteer tests.
Ethical and Other Implications
There are clearly ethical, legal and social questions and implications concerning advanced human-machine teaming. DARPA has brought in legal and ethical experts to independently advise them as N-3 technology matures. DARPA believes it can make significant strides in this 4 year project. Their goal is to provide strategic protection to soldiers. If it works, it will have implications well beyond the battlefield.