While not saying that it's not possible to implant stuff in the brain (there are
even now successes with artificial cochlea, etc.), it's not possible to
"re-engineer" the brain from without because everything that the brain does
constitutes its own re-engineering of itself... so, if something lacking that
plasticity is stuffed in-there, that thing will be as an island of
non-plasticity that just sits there, all "static" (not itself plastic), stealing
what would, otherwise, be optimized plasticity.
It's one thing to work to develop prosthetics with respect to organic damage.
It's quite another to invade fully-functional systems. While the former has a
purpose, and possible benefits, the latter does not... the fully-functional
system can only be made less than it is by mucking around with its awesome
degree of innate integration. ken collins