Simulated stuttering in non-stuttering healthy subjects: differentiating cause from consequence in developmental stuttering

Introduction Over the past decade several functional neuroimaging studies in developmental stuttering have been published. In comparison to non-stuttering volunteers, these studies revealed that adults who stutter show overactivation in areas such as the cerebellum, supplementary motor area (SMA), right frontal operculum (RFO), and the right insula. This overactivation mostly occurs bilaterally but a right-hemisphere bias can be detected. In addition, stuttering speakers show reduced activation in areas involved in auditory processing and severity of stuttering is correlated with basal ganglia (BG) activation. However, it is still unknown whether these differences point to potentially causal factors in stuttering or, alternatively, may be the result of increased effort while producing speech. Comparison of activation patterns during simulated stuttering in healthy volunteers with activation patterns in stuttering speakers might help in differentiating the cause from the consequence of the stuttering. In a previous study, using an auditory paradigm, simulated stuttering did not reveal differences in activation patterns in comparison to non-stuttered speech in healthy controls. In the present study we aimed at investigating the effects of simulated stuttering with a different, more language-based, paradigm.