Brain imaging in stuttering: where next?

As the articles comprising this special issue amply demonstrate, brain functional imaging is having a significant impact on research in persistent developmental stuttering (PDS). Specifically, voxel-wise statistical parametric images (SPI) demonstrating differences in the brain activation patterns evoked by fluent versus stuttered speech are having an impact. The first such report (Fox et al., 1996), used positron emission tomography (PET) and overt paragraph reading to show that, in broad strokes, stuttering was characterized by overactivity of the right inferior premotor cortex (operculum and insula) and underactivity of auditory cortex, abnormalities which were remediated acutely by fluency induction (chorus reading). With the several papers in this issue (and numerous intervening papers), considerable consensus about these findings has emerged. The findings have been replicated with a range of immediately and temporarily effective fluency inductions as well as with sustained improved fluency produced by behavioral treatments. They have been extended from paragraph reading to spontaneous speech and to single word tasks. They have been extended from overt speech to imagined speech and speech preparation tasks. They have been extended from PET to functional magnetic resonance imaging (fMRI). Despite significant methodological differences, the basic observations stand. Given this, the question becomes, “Where next?” How best should the PDS research community capitalize on the reliability of these findings? How do we use this new insight into stuttering? Do we try more and more task variants, to winnow our findings down to the finest, most replicable effects? Do we apply the