Abstract
Using an fMRI-based classification approach and the structural equation modeling (SEM) method, this study examined the neural bases of atypical planning and execution processes involved in stuttering. Twelve stuttering speakers and 12 controls were asked to name pictures under different conditions (single-syllable, multi-syllable, or repeated-syllable) in the scanner. The contrasts between conditions provided information about planning and execution processes. The classification analysis showed that, as compared to non-stuttering controls, stuttering speakers' atypical planning of speech was evident in their neural activities in the bilateral inferior frontal gyrus (IFG) and right putamen and their atypical execution of speech was evident in their activations in the right cerebellum and insula, left premotor area (PMA), and angular gyrus (AG). SEM results further revealed two parallel neural circuits-the basal ganglia-IFG/PMA circuit and the cerebellum-PMA circuit-that were involved in atypical planning and execution processes of stuttering, respectively. The AG appeared to be involved in the interface of atypical planning and execution in stuttering. These results are discussed in terms of their implications to the theories about stuttering and to clinical applications.
Highlights
There is accumulating evidence that atypical planning and execution processes are associated with stuttered speech
Using an functional magnetic resonance imaging (fMRI)-based classification approach, the present study revealed that statistical values extracted from the brain regions involved in atypical planning or execution could accurately discriminate stuttering speakers from non-stuttering controls
Among the brain regions involved in the task × group interaction effects, the bilateral IFG and the right putamen demonstrated the most significant contributions to atypical planning, whereas the left AG and PMA, the right insula, and the cerebellum contributed the Standardized path pb coefficients p coefficients χ2diff pb IFG, the inferior frontal gyrus; PMA, the premotor area; Cereb, the cerebellum; Angular, the angular gyrus; L, left; R, right
Summary
There is accumulating evidence that atypical planning and execution processes are associated with stuttered speech. Previous brain imaging studies have revealed widely distributed neural differences between stuttering and non-stuttering speakers, such as the the over-activation in the right frontal operculum/anterior insula and the right cerebellum, absent activation in the bilateral auditory areas, and increased or decreased activation in the motor areas and the basal ganglia (Brown et al, 2005; De Nil et al, 2008, 2000; Fox et al, 2000; Ingham et al, 2000, 2004; Neumann et al, 2003; Wu et al, 1995) It is not clear which of the above neural differences are associated with atypical planning, execution, or. This result, cannot be directly compared to those of the other two studies because it is unknown how the Go/no-Go paradigm used in Chang et al (2009) might have altered the underlying processes of word production
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