Phonological processing abilities of adults who stutter

This study investigated phonological awareness, phonological memory and rapid automatic naming abilities of adults who stutter and typically fluent peers. Many theorists posit that a delay or breakdown occurs during “phonological encoding,” or the retrieval or construction of phonological segments (Howell & Au-Yeung, 2002; Perkins, Kent & Curlee, 1991; Postma & Kolk, 1993; Wingate 1988). Efficient phonological encoding is predicated upon the ability to segment phonological representations in a rapid, precise manner. According to current theories, a delay or incomplete retrieval of lexical segments could impede the execution of the articulatory plan, thereby resulting in disfluent speech. Unfortunately, the process of phonological encoding is not directly observable and must therefore be explored though alternate processes that reflects its incremental nature. Phonological awareness, phonological memory and rapid automatic naming can be examined to accomplish this task. Several core mechanisms are utilized during phonological processing, and a deficit in any of these mechanisms could account for performance differences in phonological processing tasks. Completion of these tasks is dependent upon the quality of phonological representations in the lexicon, the ability to construct novel phonological codes online, and the ability to maintain phonological representations in memory. The process of redintegration, whereby pre-existing lexical-semantic knowledge is used to supplement decaying or delayed phonological code (Hulme et al., 1997), can also play an important role in the completion of phonological processing tasks. Participants completed several tasks examining different aspects of their phonological processing abilities. Significant between-group differences were revealed on nonlexical phonological awareness tasks, nonword repetition tasks, and rapid automatic naming tasks that used lexical stimuli. Adults who stutter performed significantly less well than typically fluent adults on tasks that used nonlexical stimuli. Adults who stutter appear to rely heavily on lexical-semantic information (redintegration) to bolster lower performance in other aspects of phonological encoding. Participants in both groups performed equally well on tasks that used lexical stimuli but not on tasks with nonlexical stimuli, indicating that between-group differences in phonological encoding exist. Differences in core mechanisms of phonological processing may reveal subtle linguistic differences that may contribute to an unstable speech system in people who stutter

Cortical dynamics of disfluency in adults who stutter

Citation: Sengupta, R., Shah, S., Loucks, T. M. J., Pelczarski, K., Scott Yaruss, J., Gore, K., & Nasir, S. M. (2017). Cortical dynamics of disfluency in adults who stutter. Physiological Reports, 5(9). doi:10.14814/phy2.13194Stuttering 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. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society