When new drugs need to be tested, the subject of those tests are usually mice. And often successful tests on mice don’t translate to success for humans simply because we aren’t mice. That’s why scientists at Johns Hopkins University have designed and grown something that could be much better test subjects for drug development: “Mini-brains”. What the scientists have done is reprogrammed adult skin cells into embryonic stem cells which are grown in petri dishes over a couple months. The scientists can then test those cells by placing them on electrode array and listening to the neurons’ electrical communication as the drugs are added. These tiny brains are about the size of houseflies so researchers can grow a hundred of them in a single petri dish. So far the experiment with mini-brains has been successful, and could potentially replace animal testing on a large scale and make for more accurate brain-related research.