This is very exciting, but of course, very scary.
I particularly like this bit:
The job of the hippocampus appears to be to "encode" experiences so they can be stored as long-term memories elsewhere in the brain. "If you lose your hippocampus you only lose the ability to store new memories," says Berger. That offers a relatively simple and safe way to test the device: (...)
It's safe to test it, because if its goes wrong, the guinea pig won't remember the whole experiment anyway.