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Haynes needed to solve his problem, to invent a completely new method of flight control. This is where the prefrontal cortex re ally demonstrates its unique strengths. It is the only brain region able to take an abstract principle—in this case, the physics of engine thrust—and apply it in an unfamiliar context to come up with an entirely original solution. It's what allowed Haynes to logically analyze the situation, to imagine his engines straighten ing his steep bank. He could model the aerodynamics in his mind. Only recently have scientists learned how the prefrontal cortex accomplishes this. The key element is a special kind of memory known as working memory. The name is accurate: by keeping information in short-term storage, where it can be ma nipulated and analyzed, the brain can work with all the informa tion streaming in from other cortical areas. It is able to determine what information, if any, is relevant to the problem it's trying to solve. For instance, studies show that neurons in the prefrontal areas will fire in response to a stimulus—such as the sight of some cockpit instrumentation—and then keep on firing for sev eral seconds after the stimulus has disappeared. This echo of ac tivity allows the brain to make creative associations as seemingly unrelated sensations and ideas overlap. (Scientists refer to this as the restructuring phase of problem-solving, since the relevant information is mixed together in new ways.) It's why Haynes could think about the thrust levers while simultaneously think ing about how to turn the plane. Once this overlapping of ideas occurs, cortical cells start to form connections that have never existed before, wiring themselves into entirely new networks. And then, after the insight has been generated, the prefrontal cortex is able to identify it: you immediately realize that this is the answer you've been searching for. "I don't know where the idea for differential thrust came from," Haynes says. "It just oc curred to me, all of a sudden, out of nowhere." From the per-