Cortical dynamics of disfluency in adults who stutter.

Ranit Sengupta,J. Scott Yaruss,Katie Gore,Kristin Pelczarski,Shalin Shah,Torrey M. J. Loucks,Sazzad M. Nasir

doi:10.14814/phy2.13194

Abstract

Stuttering is a disorder of speech production whose origins have been traced to the central nervous system. One of the factors that may underlie stuttering is aberrant neural miscommunication within the speech motor network. It is thus argued that disfluency (any interruption in the forward flow of speech) in adults who stutter (AWS) could be associated with anomalous cortical dynamics. Aberrant brain activity has been demonstrated in AWS in the absence of overt disfluency, but recording neural activity during disfluency is more challenging. The paradigm adopted here took an important step that involved overt reading of long and complex speech tokens under continuous EEG recording. Anomalies in cortical dynamics preceding disfluency were assessed by subtracting out neural activity for fluent utterances from their disfluent counterparts. Differences in EEG spectral power involving alpha, beta, and gamma bands, as well as anomalies in phase‐coherence involving the gamma band, were observed prior to the production of the disfluent utterances. These findings provide novel evidence for compromised cortical dynamics that directly precede disfluency in AWS.

Highlights

Stuttering is a communication disorder that negatively impacts the quality of life and socio-economic opportunities (Craig et al 2009; Yaruss 2010)
In a subsequent paper the cortical dynamics of stuttering trait will be investigated by comparing the fluent utterances of adults who stutter (AWS) with those from fluent adults
Most studies of the neurology of stuttering have focused on brain activity during fluent speech or covert language processing due to the difficulty of studying neural function during moments of disfluency

Summary

Introduction

Stuttering is a communication disorder that negatively impacts the quality of life and socio-economic opportunities (Craig et al 2009; Yaruss 2010). MEG (magnetoencephalography) and EEG (electroencephalography) studies have shown that overt speech-related activities elicit aberrant brain activity (Salmelin et al 2000; Beal et al 2010, 2011) Despite such promising research, the temporal dynamics of exactly what transpires in neural processing immediately prior to or during the production of disfluent speech (any interruption in the forward flow of speech) remains poorly understood. The temporal dynamics of exactly what transpires in neural processing immediately prior to or during the production of disfluent speech (any interruption in the forward flow of speech) remains poorly understood Such information is critical to the understanding of stuttering, as disfluent episodes may manifest markedly distinct brain activation than fluent utterances (Jiang et al 2012). Several scenarios could account for this miscommunication with one potential factor being sensorimotor “disintegration” (Guenther 2006; Beal et al 2010; Sengupta et al 2016b)

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