Phonological working memory in developmental stuttering: Potential insights from the neurobiology of language and cognition

The Application of EEG Mu Rhythm Measures to Neurophysiological Research in Stuttering

“…The task requires listening to and encoding the sounds, holding them in working memory, and then reproducing the sounds in the order in which they were presented. A growing body of evidence implicates load-dependent differences in nonword repetition in both children (CWS) and adults (AWS) who stutter compared to matched controls (Bowers et al, 2018;Ofoe et al, 2018). Recent studies investigating nonword repetition tasks have demonstrated overall lower performance in both preschool CWS (Spencer and Weber-Fox, 2014;Pelczarski and Yaruss, 2016) and AWS (Byrd et al, 2012(Byrd et al, , 2015(Byrd et al, , 2017(Byrd et al, , 2018Coalson and Byrd, 2017).…”

“…In preschool CWS, the available evidence suggests that differences in nonword repetition are subclinical and load-dependent and in adults differences are apparent only under high loads at the limit of typical capacity to hold speech sounds in memory (e.g., 7 syllable nonwords) or under other syllable stress-related load manipulations (Bowers et al, 2018). Further, nonword repetition has been reported to differentiate preschool CWS who persist from those who recover, suggesting that the underlying cognitive capacities supporting PWM may be a marker for the phenotypic expression of recovery or persistence among other cognitive-linguistic capacities (e.g., syntax; Spencer and Weber- Fox, 2014;Usler and Weber-Fox, 2015).…”

“…Further, nonword repetition has been reported to differentiate preschool CWS who persist from those who recover, suggesting that the underlying cognitive capacities supporting PWM may be a marker for the phenotypic expression of recovery or persistence among other cognitive-linguistic capacities (e.g., syntax; Spencer and Weber- Fox, 2014;Usler and Weber-Fox, 2015). Despite its potential significance as a simple measure that could be useful both in a clinical setting and as a construct in theoretical frameworks, one barrier to understanding why CWS and AWS are different on the task has been separating various cognitive and corresponding neurophysiological processes associated with task performance and behavioral accuracy (Bowers et al, 2018).…”

“…As an example, speech-motor output, measured as incoordination in speech articulators (i.e., lip aperture variability), differs significantly in a nonword repetition tasks even when no behavioral differences are observed at lower loads (e.g., 4 syllable repetition), suggesting that while motor control differs in AWS and CWS it may be distinct from behavioral accuracy (Smith et al, 2010(Smith et al, , 2012. As such, it will be critical in the future to enhance understanding of what cognitive and sensorimotor processes are related to or mediate differences in nonword repetition performance and in turn the mechanistic processes underlying differences in PWM (Bowers et al, 2018).…”

“…Current theoretical frameworks designed to account for recent neuroimaging findings in CWS have also suggested that stuttering may arise from subtle differences in the coordination of large-scale cortical-subcortical networks central to which is a deficit in coordinative sensorimotor timing . Thus, a timing deficit related to the sensorimotor control of speech has the potential to account for load-dependent differences in tasks loading PWM and in speech output in more naturalistic conditions (Bowers et al, 2018). Recent EEG studies of neural oscillations using word and nonword repetition tasks suggest that power and measures of interelectrode coordination (i.e., phase coherence) are related to stuttered or fluent speech production trials (Sengupta et al, 2017).…”