The cognitive-augmentation frontier

Almost all clinical BCI restores lost function; augmenting a healthy brain, by expanding memory, adding a sense, or speeding communication beyond natural limits, is a distinct and far more speculative frontier. The read/write asymmetry, biocompatibility risk, and the co-adaptation ceiling all bite hardest here, because a healthy user has a high natural baseline and a low tolerance for surgical risk, so the benefit must be large and the interface exceptionally safe to be worth it.

There are also conceptual limits: adding raw information does not obviously raise the roughly-bounded rate at which a person can act on it, so augmentation may be constrained by cognition rather than by the interface. Serious analysis separates plausible near-term augmentation, such as offloading to external tools, sensory substitution, and attention aids, from the far more contested prospect of directly raising general cognitive capacity, which has no demonstration and deep open questions.