Yes, that's one among many differences between the brains of people who stutter and people who do not. The jury is still out on what in the brain is causing stuttering. It's too early to hone in on one region. Differences in blood flow may suggest differences in neural activity, but is this cause or effect? We don't know enough yet. And yes, I'm saying that without a control a neurologist would say, "this is a normal brain." There is a great deal of variability between normal brains. The differences we observe are averages between two groups of brains that are, for the most part (really in all cases but one), functioning normally. Thus, the differences we see are only observable when we have lots of brains to compare. I don't think we have learned enough about the brain to make predictive statements about an individual PWS's neurophysiology. One day, perhaps. But I don't think we are there yet. The same is true of other disorders, we don't know about the neurophysiology of most mental or behavioral disorder. We use imaging techniques for the medical diagnosis of gross structural abnormalities (e.g., tumors, strokes etc). Epilepsy is one of few exceptions -- but the atypical activity in epilepsy is profound. The technology isn't sensitive enough yet for stuttering. We use these medical technologies to learn about what might be going on, but we don't have the technology to detect these minor differences yet.