2017 Volume 41 Issue 1 Pages 33-44
Using the delayed auditory feedback (DAF) condition, in which one hears his/her own speech with a delay of a few hundred milliseconds, some stutterers show improvement in their stuttering symptoms. However, the underlying mechanisms of the effect of DAF on stutterers and the reported interindividual variabilities have not been clarified. To examine the relationship between DAF effect and brain activity, we used near-infrared spectroscopy (NIRS) on 11 stutterers to record their brain activity under normal auditory feedback (NAF) and DAF conditions. The DAF induced a more pronounced increase in oxygenated hemoglobin in the left precentral and left inferior frontal gyri compared with the NAF. We next divided the stutterers into two groups based on their behavioral indicators after DAF, seven stutterers whose disfluency had worsened and four whose disfluency had improved, and explored their brain activity. The results revealed elevated brain activity in the right superior temporal gyrus in those with worsened stuttering, while those with improved stuttering displayed an increase in the activity proximity of the left superior temporal and left precentral gyri. These findings suggest that stutterers may comprise distinct subgroups that present different characteristics of their auditory information processing system.
