A new report from the Center for Disease Control shows the incidence of autism in American children has dramatically increased over the last decade. A debate is raging over why. Some experts say better detection is the reason. Others say it reflects the broadening definition of autism. At the same time, medical breakthroughs have given doctors and researchers hope that they may soon be better able to identify what causes autism -- and how to treat it. What new research means for our understanding of autism.