That study is mindblowing. The authors found a physical source of stuttering. They showed how brain activation during speech differs between stutterers and fluent speakers. They saw how fluency-shaping therapy changes the activation patterns in stutterers. AND THEN they measured "recovered stutterers" - not fully cured, just significantly reduced dysfluency - and found they had a completely different activation pattern than fluent people and other stutterers! There was no clear explanation for how the recovered stutterers' brains adapted to a more effective pattern, but if we can figure that out it would be a HUGE step forward for stutterers. I would probably qualify as a "recovered stutterer" myself. The study points to listening to the sound of your own voice, and learning to keep a steady beat. I also propose that practicing reading aloud helps; I feel that way from my own experience, and it might agree with the data, but we need more research.