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. 2025 Sep 26;20(9):e0333205.
doi: 10.1371/journal.pone.0333205. eCollection 2025.

Differential involvement of feedback and feedforward control networks across disfluency types in adults who stutter: Evidence from resting state functional connectivity

Hannah P Rowe  1   2 , Saul A Frankford  2   3 , Jackie S Kim  2 , Jason A Tourville  2 , Alfonso Nieto-Castanon  2 , Frank H Guenther  2   4   5   6
Affiliations

Differential involvement of feedback and feedforward control networks across disfluency types in adults who stutter: Evidence from resting state functional connectivity

Hannah P Rowe et al. PLoS One. .

Abstract

Purpose: This study investigated the relationship between different disfluency types (i.e., repetitions, prolongations, and blocks) and resting state functional connectivity in the feedback (FB) and feedforward (FF) control networks in 20 adults who stutter.

Methods: Frequency of each disfluency type was coded in speech samples derived from the Stuttering Severity Instrument, and functional connectivity between brain regions of interest was derived from resting state functional magnetic resonance imaging scans. We used LASSO regressions to identify the connections that most strongly predicted each disfluency type.

Results: Both repetitions and prolongations were significantly associated with increased connectivity in left ventral motor cortex - right ventral premotor cortex, which is hypothesized to be involved in FB control of speech. In contrast, blocks were significantly associated with reduced connectivity in right anterior cerebellum - left ventral lateral thalamic nucleus and increased connectivity in left presupplementary motor area - left posterior inferior frontal sulcus, both of which are hypothesized to be involved in FF control of speech.

Conclusion: Our findings suggest that repetitions and prolongations may be associated with increased reliance on FB-based corrective mechanisms, whereas blocks may be associated with disrupted FF-based initiation mechanisms. These neural underpinnings may correspond to different challenges in terminating or initiating motor commands and underscore the nuanced neurobiological processes underlying speech disfluencies.

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Conflict of interest statement

Frank Guenther receives royalties for his book Neural Control of Speech from MIT Press. All other authors have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Figures

Fig 1
Fig 1. Heatmap of LASSO regression coefficients averaged across 1000 bootstrapped iterations.
Color intensity = coefficient magnitude; black rectangles = most consistently selected predictors; a/pCb = anterior/posterior cerebellum; GP = globus pallidus; H = Heschl’s gyrus; MG = medial geniculate thalamic nucleus; pAC = posterior auditory cortex; pIFS = posterior inferior frontal sulcus; preSMA = presupplementary motor area; pSTG = posterior superior temporal cortex; PT = planum temporale; SMA = supplementary motor area; VA = ventral anterior thalamic nucleus; VL = ventral lateral thalamic nucleus; vMC = ventral motor cortex; vPMC = ventral premotor cortex; VPM = ventral posterior medial thalamic nucleus; vSC = ventral somatosensory cortex.
Fig 2
Fig 2. Correlations between repetition rate (panel A), prolongation rate (panel B), and block rate (panel C) and functional connectivity in the feedback and feedforward control networks.
Colored dots = individual participants; aCb = anterior cerebellum; pIFS = posterior inferior frontal sulcus; preSMA = presupplementary motor area; VL = ventral lateral thalamic nucleus; vMC = ventral motor cortex; vPMC = ventral premotor cortex.
Fig 3
Fig 3. Current findings within the frameworks of Directions Into Velocities of Articulators (DIVA) and Gradient Order DIVA (GODIVA).
Cb = cerebellum; GP = globus pallidus; MG = medial geniculate thalamic nucleus; pAC = posterior auditory cortex; pIFS = posterior inferior frontal sulcus; SMA = supplementary motor area; VA = ventral anterior thalamic nucleus; VL = ventral lateral thalamic nucleus; vMC = ventral motor cortex; VPM = ventral posterior medial thalamic nucleus; vPMC = ventral primary motor cortex; vSC = ventral somatosensory cortex; + = positive correlation between disfluency rate and connection strength; - = negative correlation between disfluency rate and connection strength; pros = prolongations; reps = repetitions.
Fig 4
Fig 4. Schematic of the brain connections associated with each disfluency type.
Red line = repetitions; green line = prolongations; blue line = blocks; aCb = anterior cerebellum; pIFS = posterior inferior frontal sulcus; preSMA = presupplementary motor area; VL = ventral lateral thalamic nucleus; vMC = ventral motor cortex; vPMC = ventral premotor cortex; + = positive correlation between disfluency rate and connection strength; - = negative correlation between disfluency rate and connection strength; pros = prolongations; reps = repetitions.
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References

    1. Smith A. Stuttering: a unified approach to a multifactorial, dynamic disorder. In: Bernstein Ratner N, Healey EC, editors. Stuttering research and practice: bridging the gap. 1st ed. Hove, United Kingdom: Psychology Press. 1999. p. 27–44.
    1. Yairi E, Ambrose N. Epidemiology of stuttering: 21st century advances. J Fluency Disord. 2013;38(2):66–87. doi: 10.1016/j.jfludis.2012.11.002 - DOI - PMC - PubMed
    1. Connery A, McCurtin A, Robinson K. The lived experience of stuttering: a synthesis of qualitative studies with implications for rehabilitation. Disabil Rehabil. 2020;42(16):2232–42. doi: 10.1080/09638288.2018.1555623 - DOI - PubMed
    1. Ambrose NG, Yairi E. Normative disfluency data for early childhood stuttering. J Speech Lang Hear Res. 1999;42(4):895–909. doi: 10.1044/jslhr.4204.895 - DOI - PubMed
    1. Froeschels E. Pathology and therapy of stuttering. Nerv Child. 1943;2:148–61.