It almost goes without saying that brain surgery requires extreme precision, but there hasn't been much advancement in brain mapping techniques for the past two decades. What good is a breakthrough procedure if you're still using bulky, imprecise 1990s-era technology as a guide? Researchers may have a better way: they've developed an electrode grid-based brain mapping tool that's both much easier to wield and far more precise. Instead of relying on the usual metal electrodes, they switched to a conductive polymer that's so tiny and thin it makes Saran Wrap look ungainly. That, in turn, let them stuff 25 times more electrodes into the same space while slimming their tool down to just 0.0002 inches thick instead of a few tenths of an inch.