In research clearly inspired by Dr. Moreau, mice had human brain cells spliced into their little mousy brains. It made them smarter.
Specifically, the mice were given glial cells from humans, through a process that involved injecting the cells into the skulls of baby mice. Mice have glial cells too, but those are much different in their functioning. And apparently, the human cells did wonders for the cheese-eating vermin:
Long-term potentiation (LTP) was sharply enhanced in the human glial chimeric mice, as was their learning, as assessed by Barnes maze navigation, object-location memory, and both contextual and tone fear conditioning.
There were no reports of repeated attempts to try and take over the world, but we wouldn’t be surprised at any misplaced lab equipment.
To be fair, this wasn’t to create a race of supermice that would ultimately overwhelm humanity and replace us, but rather to demonstrate that human glial cells were a key part of improving brain function. With this better understanding of the cell, we’re on the road to better understanding, and possible more effectively treating, certain brain disorders.
So, that’s great and all, guys, but you really need to bioengineer the Animaniacs before Hollywood gets all feisty and turns it into a crappy CGI/live-action hybrid.