From time to time, I do a keyword search on "stuttering" in PubMedline , which is an archive that contains abstracts of all published articles. It is a really useful way to stay updated with the latest research on PDS. Of course, most research is a year old or so when it appears, as the authors have to go through the tedious review process, but nevertheless. I also face the problem that I can only look at the abstracts as I dont have access to the fee-based journals. So I always need to plea with the authors to send me the pdf file of their paper!
I always look for the most recent articles, and on Monday came across an article by Brown, Ingham, Ingham, Laird and Fox. The group around Prof Ingham (UC at Santa Barbara) is one of the most active research groups in the field of brain imaging, actually probably the leading one because they have both expertise in brain imaging studies (together with Prof Fox's group at San Antonio, Texas, who had the first PET study out on the PDS brain) and on PDS itself. Many groups are either very good at brain imaging or understand PDS very well.
So what's in the article? Well, they do a meta-analysis of previous brain imaging studies using a statistical method called ALE. I dont know this method or how it works (as always there are probably some assumptions made...), but let's take it as God given. They have included brain scans from the research groups Fox/Ingham, de Nil from Toronto , and Neumann/Preibisch from Frankfurt. These groups have been quite active over the last years. Especially, the Frankfurt group around Neumann which is currently scanning people, especially those that have stuttered as kids but not adults, see their call for volunteers (in German).
Back to the article, first, Braun, InghamS, et al find that disfluent speech is different in brain activation level in three areas:
1) overactive motor regions and cerebellar vermis
2) atypical right-brain activiation (typically speech is processed in the left brain)
3) underactivation in auditory regions.
Second, they propose a (testable) theory of stuttering, which I will discuss tomorrow plus the general difficulties to construct a theory of stuttering.