Stuttering is linked to sensorimotor deficits related to internal modeling mechanisms. This study compared spectral power and oscillatory activity of EEG mu (μ) rhythms between persons who stutter (PWS) and controls in listening and auditory discrimination tasks. EEG data were analyzed from passive listening in noise and accurate (same/different) discrimination of tones or syllables in quiet and noisy backgrounds. Independent component analysis identified left and/or right μ rhythms with characteristic alpha (α) and beta (β) peaks localized to premotor/motor regions in 23 of 27 people who stutter (PWS) and 24 of 27 controls. PWS produced μ spectra with reduced β amplitudes across conditions, suggesting reduced forward modeling capacity. Group time-frequency differences were associated with noisy conditions only. PWS showed increased μ-β desynchronization when listening to noise and early in discrimination events, suggesting evidence of heightened motor activity that might be related to forward modeling deficits. PWS also showed reduced μ-α synchronization in discrimination conditions, indicating reduced sensory gating. Together these findings indicate spectral and oscillatory analyses of μ rhythms are sensitive to stuttering. More specifically, these analyses can reveal stuttering-related sensorimotor processing differences in passive listening and auditory discrimination tasks which may be influenced by basal ganglia deficits.

Objective: To determine whether changes in sensorimotor control resulting from speaking conditions that induce fluency in people who stutter (PWS) can be measured using electroencephalographic (EEG) mu rhythms in neurotypical speakers.Methods: Non-stuttering (NS) adults spoke in one control condition (solo speaking) and four experimental conditions (choral speech, delayed auditory feedback (DAF), prolonged speech and pseudostuttering). Independent component analysis (ICA) was used to identify sensorimotor μ components from EEG recordings. Time-frequency analyses measured μ-alpha (8–13 Hz) and μ-beta (15–25 Hz) event-related synchronization (ERS) and desynchronization (ERD) during each speech condition.Results: 19/24 participants contributed μ components. Relative to the control condition, the choral and DAF conditions elicited increases in μ-alpha ERD in the right hemisphere. In the pseudostuttering condition, increases in μ-beta ERD were observed in the left hemisphere. No differences were present between the prolonged speech and control conditions.Conclusions: Differences observed in the experimental conditions are thought to reflect sensorimotor control changes. Increases in right hemisphere μ-alpha ERD likely reflect increased reliance on auditory information, including auditory feedback, during the choral and DAF conditions. In the left hemisphere, increases in μ-beta ERD during pseudostuttering may have resulted from the different movement characteristics of this task compared with the solo speaking task. Relationships to findings in stuttering are discussed.Significance: Changes in sensorimotor control related feedforward and feedback control in fluency-enhancing speech manipulations can be measured using time-frequency decompositions of EEG μ rhythms in neurotypical speakers. This quiet, non-invasive, and temporally sensitive technique may be applied to learn more about normal sensorimotor control and fluency enhancement in PWS.

The NEO-FFI has been widely used to demonstrate personality differences between people who stutter (PWS) and those who do not. These differences can be interpreted as indicators of internal sources of disability that contribute to handicaps associated with stuttering. The aim of the current study was to use this same tool to determine the perceived impact of stuttering on personality in order to provide a similar indicator of how external factors may contribute to the stuttering disability. A total of 49 non-stuttering young adults were given the NEO-FFI-3 after watching a video of someone stuttering (moderately to severely) and after watching a video of someone speaking fluently. Participants were asked to answer test items while imagining that they had spoken like the persons in the videos for their entire lives. When asked to assume the stuttering perspective, participants reported themselves to be significantly more neurotic (P < 0.01) and less extraverted (P < 0.01) than when they assumed the perspective of the fluent speaker. The large differences (∼10 points; greater than one standard deviation) in these domains between the fluent and stuttered perspectives are consistent with existing stereotypes about PWS. These differences are greater than and only partially consistent with differences in personality found between PWS and non-stuttering individuals. The findings support the notion that external factors (e.g. listener reactions and stereotypes about PWS) contribute strongly to the manner in which stuttering restricts function and results in handicaps.