Christy Ludlow is heading a research team at NIH: see here. She is quite a dynamic multi-area scientist not only working on stuttering but also for example on swallow disorders. She has published an interesting article A Dynamic Motor Control Disorder where she and Loucks puts forward the idea that stuttering is a system disorder and that no single area is defect as such:
...the central control abnormalities in stuttering are not due to disturbance in one particular brain region but rather a system dysfunction that interferes with rapid and dynamic speech processing for production.Admittedly, the article is very vague on details of an underlying mechanism, and does not provide proofs as such. They rather draw their conclusions on what makes most sense given all the observations on stuttering and related disorder. And, I completely share the system disorder idea and have written about similar ideas like the traffic-jam prone transport system of a city: see here. Actually, I have a hard time to see how stuttering could not be a system disorder given our current knowledge and the considerable variability of effects, and unfortunately also how you would actually prove this with the current data!
During her talk, she made a few interesting observations. First, 37% of people with acquired stuttering after brain injury reported that they stuttered as kids! Second, none seem to have lesions in speech and language areas but connecting areas. She also said that about 50% of the kids who stuttered after age 6 recover. (I have never come across this observation, but I do remember that my professor at Imperial College in London said that he stuttered as a teenager and then it went away...) And 50% of stuttering kids have concomitant (or in plain English "also other"!) disorders. She also spent time talking about possible models of a neural basis of stuttering and mentioned possible starting points like delayed or abnormal development of fiber tracts, genetic predisposition, and cell migration and neural pruning. A brain with such a starting deficit would then be modulated both neurologically and behaviourally by reaction to stuttering. But she did not commit to any specific direction. To be honest, I did not remember most, but I see her efforts as a clear attempt to put some meat on the bones of her system dysfunction idea from the above article.