It’s been more than a century since Spanish neuroanatomist Santiago Ramón y Cajal won the Nobel Prize for illustrating the way neurons allow you to walk, talk, think, and be. In the intervening hundred years, modern neuroscience hasn’t progressed that much in how it distinguishes one kind of neuron from another. Sure, the microscopes are better, but brain cells are still primarily defined by two labor-intensive characteristics: how they look and how they fire.