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Beta Oscillatory Dynamics in Response to Auditory Feedback Alterations in Adults Who Stutter
Shogo Honda1, Ayoub Daliri1; 1Arizona State University
Beta oscillations, which are associated with sensorimotor processing and motor control in the cortical-basal ganglia motor network, are consistently modulated by movement; beta rhythms are suppressed before and during movement (McFarland et al., 2000; Pfurtscheller & Lopes Da Silva, 1999). In the context of stuttering, disrupted predictive control has been proposed as a core neural deficit, potentially leading to increased reliance on auditory feedback and less efficient feedforward control (Kittilstved et al., 2018). Electroencephalogram (EEG) studies consistently report atypical beta modulation in adults who stutter (AWS) before and during speech; however, the nature and functional significance of these abnormalities remain unclear (Caruso et al., 2022). To address these questions, we analyzed EEG data from AWS and adults who do not stutter (AWNS) across two independent experiments that shared comparable designs (Daliri & Max, 2015, 2018). In both experiments, participants engaged in speech tasks with and without real-time auditory feedback alterations. For the purposes of this study, we focused on conditions that excluded external auditory stimuli (pure tones) to isolate the neural dynamics associated with speech planning. Conditions included reading aloud with non-delayed auditory feedback, delayed auditory feedback, and silent reading in the first dataset, and reading aloud with non-delayed auditory feedback, and silent reading in the second. Our analysis centered on beta oscillatory activity during speech preparation, with specific attention to hemispheric asymmetries in beta suppression. We observed a consistent pattern of increased beta suppression in AWS compared to AWNS, particularly in the right hemisphere. Furthermore, when auditory feedback was altered in the original experiments, AWS and AWNS exhibited different patterns of beta power modulation in response to these changes, suggesting divergent neural strategies for processing speech errors. These group differences may reflect a reduced ability in AWS to generate accurate internal predictions and an overreliance on external feedback. Together, these findings highlight beta oscillations as a neural marker of both anticipatory speech control and feedback evaluation. The observed asymmetries and modulation patterns contribute to a growing body of evidence pointing to disrupted sensorimotor integration in stuttering (Caruso et al., 2022; Jenson et al., 2018; Mersov et al., 2016). Our work emphasizes the importance of examining beta activity both in the absence of feedback and in response to its alteration to better understand the multifaceted nature of stuttering. Future research will extend this work by linking beta dynamics more directly to behavioral measures of speech fluency and exploring their potential as targets for neuromodulation-based intervention.
Topic Areas: Disorders: Developmental, Speech Motor Control