Neural synchrony reflects closure of jabberwocky noun phrases but not predictable pseudoword sequences.

Successful language comprehension requires the combination of individual words into larger linguistic units. In the present minimal-phrase study, we used electroencephalography (EEG) to investigate whether syntactic combination is indexed by changes in neural synchrony, while testing for both token-based and type-based effects. To do this, we analysed intertrial phase coherence (ITPC) elicited by reading two item (words or pseudowords) phrases that were either unifiable or nonunifiable. Results indicated that type-based unifiable phrases elicited increased ITPC relative to all other conditions in the frequency band corresponding to the rate of phrases (0.5 Hz) but not the rate of words (1 Hz). Conversely, we observed a complementary pattern for the N400, which was more sensitive to token-based effects. These findings provide evidence that the combination of single words into larger syntactic structures may be indexed by the synchronous firing of assemblies of neurons oscillating at the rate of phrases during reading.

Influences of cognitive load on sensorimotor contributions to working memory: An EEG investigation of mu rhythm activity during speech discrimination.

Sensorimotor activity during speech perception is highly variable and is thought to be related to the underlying cognitive processes recruited to meet task demands. The purpose of the current study was to evaluate the impact of cognitive load on sensorimotor-based attention and working memory processes during speech perception. Manipulations of set size and signal clarity were employed to alter cognitive load. Raw EEG data recorded from 42 subjects during accurate discrimination of CV syllable pairs were decomposed by Independent component analysis; identifying sensorimotor mu components from 37 subjects. Time-frequency analyses revealed event related desynchronization (ERD) across alpha and beta frequency bands during and following stimulus presentation in all conditions, reflecting working memory maintenance through covert articulatory rehearsal. No early attentional activity was observed, suggesting adaptation to tasks. However, modulation of late working memory activity was observed between degraded and non-degraded conditions. Weak and delayed alpha and beta ERD in degraded conditions were interpreted as evidence of delayed implementation of covert rehearsal due to the prolonged time necessary to extract a phonological representation from the auditory signal. Findings are interpreted within Analysis by Synthesis to characterize the multi-faceted and temporally distinct contributions of anterior sensorimotor regions to working memory in support of speech discrimination.

Power and phase coherence in sensorimotor mu and temporal lobe alpha components during covert and overt syllable production.

The sensorimotor dorsal stream is known to activate in both overt and covert speech production. However, overt production produces sensory consequences that are absent during covert production. Thus, the purpose of the current study is to investigate differences in dorsal stream activity between these two production conditions across the time course of utterances. Electroencephalography (EEG) was recorded from 68 channels while 23 participants overtly (Op) and covertly (Cp) produced orthographically cued bisyllabic targets. Sensorimotor mu and auditory alpha components (from anterior and posterior aspects of the dorsal stream) were identified using independent component analysis (ICA). Event-related spectral perturbation (ERSP) analyses identified changes in mu and alpha oscillatory power over time, while intercomponent phase coherence (IPC) measured anterior-posterior connectivity in the two conditions. Results showed greater beta (15-25 Hz) suppression during speech planning across left and right hemisphere sensorimotor and temporal ICs for Op relative to Cp. By contrast, greater intrahemispheric beta coherence was observed for Cp compared to Op during speech planning. During execution, greater beta suppression was observed along with greater low frequency (< 10 Hz) power enhancement and intrahemispheric phase coherence in Op compared to Cp. The findings implicate low frequency sensorimotor and posterior temporal phase coherence in the integration of somatosensory and acoustic feedback in overt relative to covert execution. Findings are consistent with early frontal-temporal forward models involved in planning and execution with modulations depending on whether the task goal is internal or overt syllable production.

EEG Mu (µ) rhythm spectra and oscillatory activity differentiate stuttering from non-stuttering adults.

Stuttering is linked to sensorimotor deficits related to internal modeling mechanisms. This study compared spectral power and oscillatory activity of EEG mu (µ) rhythms between persons who stutter (PWS) and controls in listening and auditory discrimination tasks. EEG data were analyzed from passive listening in noise and accurate (same/different) discrimination of tones or syllables in quiet and noisy backgrounds. Independent component analysis identified left and/or right µ rhythms with characteristic alpha (α) and beta (ß) peaks localized to premotor/motor regions in 23 of 27 people who stutter (PWS) and 24 of 27 controls. PWS produced µ spectra with reduced ß amplitudes across conditions, suggesting reduced forward modeling capacity. Group time-frequency differences were associated with noisy conditions only. PWS showed increased µ-ß desynchronization when listening to noise and early in discrimination events, suggesting evidence of heightened motor activity that might be related to forward modeling deficits. PWS also showed reduced µ-α synchronization in discrimination conditions, indicating reduced sensory gating. Together these findings indicate spectral and oscillatory analyses of µ rhythms are sensitive to stuttering. More specifically, they can reveal stuttering-related sensorimotor processing differences in listening and auditory discrimination that also may be influenced by basal ganglia deficits.

Dynamic auditory contributions to error detection revealed in the discrimination of Same and Different syllable pairs.

During speech production auditory and motor regions within the sensorimotor dorsal stream operate in concert to facilitate online error detection. As the dorsal stream also is known to activate in speech perception, the purpose of the current study was to probe the role of auditory regions in error detection during auditory discrimination tasks as stimuli are encoded and maintained in working memory. A priori assumptions are that sensory mismatch (i.e., error) occurs during the discrimination of Different (mismatched) but not Same (matched) syllable pairs. Independent component analysis was applied to raw EEG data recorded from 42 participants to identify bilateral auditory alpha rhythms, which were decomposed across time and frequency to reveal robust patterns of event related synchronization (ERS; inhibition) and desynchronization (ERD; processing) over the time course of discrimination events. Results were characterized by bilateral peri-stimulus alpha ERD transitioning to alpha ERS in the late trial epoch, with ERD interpreted as evidence of working memory encoding via Analysis by Synthesis and ERS considered evidence of speech-induced-suppression arising during covert articulatory rehearsal to facilitate working memory maintenance. The transition from ERD to ERS occurred later in the left hemisphere for Different trials than for Same trials, with ERD and ERS temporally overlapping during the early post-stimulus window. Results were interpreted to suggest that the sensory mismatch (i.e., error) arising from the comparison of the first and second syllable elicits further processing in the left hemisphere to support working memory encoding and maintenance. Results are consistent with auditory contributions to error detection during both encoding and maintenance stages of working memory, with encoding stage error detection associated with stimulus concordance and maintenance stage error detection associated with task-specific retention demands.

The inhibition of stuttering via the perceptions and production of syllable repetitions.

In contrast to most therapeutic protocols for stuttering that induce fluency while producing speech targets, we investigated the possibility of inducing "carry-over" fluency prior to normal speech production. Ten adults who stutter read 7-12 syllable phrases after actively producing (via shadowing) or passively listening to: (a) repeating syllables, matched to the initial syllable of the target utterance; (b) repeating syllables, not matched to the initial syllable of the target; (c) nonrepeating syllables; and (d) fricative /noise-like acoustic signals. Relative to baseline, all active syllabic conditions produced approximately 70% inhibition (reduction) of stuttering in the ensuing target utterances, which is attributed to carry-over from fluent shadowing. The most robust passive inhibition (56%) resulted from listening to matched repeating syllables. These findings further sustain that a perception-production link in speech, possibly resulting from mirror neuron activity, can facilitate the inhibition of stuttering. However, in this study we further demonstrate gestural and temporal flexibility of this mechanism, showing that this inhibitory strategy may be enacted prior to producing speech targets. We discuss possible clinical implications and draw comparisons between core stuttering behaviors (i.e., repetitions and prolongations) and behavioral therapeutic strategies (e.g., slowed speech, preparatory sets) used to inhibit or eliminate stuttering.

Stuttering inhibition via visual feedback at normal and fast speech rates.

BACKGROUND: Immediate and drastic reductions in stuttering are found when speech is produced in conjunction with a variety of second signals (for example, auditory choral speech and its permutations, and delayed auditory feedback). Initially, researchers suggested a decreased speech rate as a plausible explanation for the reduction in stuttering as people who stutter produced speech under second signals. However, this explanation was refuted by research findings that demonstrated reductions in stuttering at both normal and fast speech rates under second signals. Recent studies have also demonstrated significant reductions in stuttering from second signals delivered via the visual modality. However, the question as to whether stuttering can be substantially reduced at normal and fast speech rates under visual speech feedback conditions has yet to be answered. AIMS: The current study investigated stuttering frequency reduction at normal and fast speech rates across different visual speech feedback conditions relative to a no-visual feedback condition. METHODS & PROCEDURES: Ten adults who stutter recited memorized tokens of eight to 13 syllables under five visual speech feedback conditions at both normal and fast speech rates. Visual speech feedback conditions consisted of participants viewing the lower portion of their face (that is, lips, jaw, and base of the nose) on a monitor as they produced the aforementioned utterances. Conditions consisted of (1) no-visual feedback condition, (2) 0 ms (simultaneous visual speech feedback), (2) a 50-ms delay, (3) a 200-ms delay, and (4) a 400-ms delay. OUTCOMES & RESULTS: A significant main effect of visual speech feedback on stuttering frequency was found (p= 0.001) with no significant main effect of speech rate or the interaction between speech rate and visual speech feedback. Relative to the no-visual feedback condition, the feedback conditions produced reductions in stuttering ranging from 27% (0 ms) to 62% (400 ms). Post-hoc comparisons revealed that all of the delay conditions differed significantly from the simultaneous feedback (p= 0.017) and the no-visual feedback conditions (p= 0.0002) while no significant differences between delay conditions (that is, 50, 200, and 400 ms) were observed. CONCLUSIONS & IMPLICATIONS: The current findings demonstrate the capabilities of visual speech feedback signals to reduce stuttering frequency that is independent of the speaker's rate of speech. Possible strategies are suggested to transfer these findings into naturalistic and clinical settings, though further research is warranted.

Sensorimotor contributions to working memory differ between the discrimination of Same and Different syllable pairs.

Sensorimotor activity during speech perception is both pervasive and highly variable, changing as a function of the cognitive demands imposed by the task. The purpose of the current study was to evaluate whether the discrimination of Same (matched) and Different (unmatched) syllable pairs elicit different patterns of sensorimotor activity as stimuli are processed in working memory. Raw EEG data recorded from 42 participants were decomposed with independent component analysis to identify bilateral sensorimotor mu rhythms from 36 subjects. Time frequency decomposition of mu rhythms revealed concurrent event related desynchronization (ERD) in alpha and beta frequency bands across the peri- and post-stimulus time periods, which were interpreted as evidence of sensorimotor contributions to working memory encoding and maintenance. Left hemisphere alpha/beta ERD was stronger in Different trials than Same trials during the post-stimulus period, while right hemisphere alpha/beta ERD was stronger in Same trials than Different trials. A between-hemispheres contrast revealed no differences during Same trials, while post-stimulus alpha/beta ERD was stronger in the left hemisphere than the right during Different trials. Results were interpreted to suggest that predictive coding mechanisms lead to repetition suppression effects in Same trials. Mismatches arising from predictive coding mechanisms in Different trials shift subsequent working memory processing to the speech-dominant left hemisphere. Findings clarify how sensorimotor activity differentially supports working memory encoding and maintenance stages during speech discrimination tasks and have potential to inform sensorimotor models of speech perception and working memory.

The perceived impact of fluency on personalities of adults who stutter: implicit evidence of self-stigma.

PURPOSE: The NEO-FFI is an extensively used instrument that has been used to identify personality differences between those who stutter and matched controls or group norms. The goal of this study was to use the NEO-FFI to implicitly capture and quantify self-stigma related to personality in persons who stutter (PWS). METHODS: Thirty PWS completed the NEO-FFI twice; once as themselves and once while mentalizing (using theory of mind) to respond as though they did not stutter and had never stuttered, thus comparing their true personality to their perceived personality if they were fluent speakers. Compared to their true personalities, PWS perceived their fluent counterparts to be significantly less neurotic and more extroverted. RESULTS: The differences observed are somewhat analogous, though considerably larger in magnitude than personality differences that have previously been reported when comparing PWS to fluent controls or norms. Differences were interpreted to be due to "contrast effects" influencing the comparison. That is, PWS cognitively separated themselves from their fluent counterparts, seeing their true selves in a negative light compared to their fluent counterparts. This "us" vs. "them" separation is considered evidence of self-stigma related to personality in PWS. CONCLUSIONS: The finding that the perceived differences were in the domains of Neuroticism and Extraversion is consistent with prevailing stereotypes about PWS and exemplifies how public stigma can become internalized. Clinical implications are discussed with respect to how similar theory of mind/social comparison exercises can be used in cognitive behavioral therapy to help identify and restructure negative thoughts and beliefs about stuttering.

Stuttered and fluent speakers' heart rate and skin conductance in response to fluent and stuttered speech.

BACKGROUND: Previous studies have found simultaneous increases in skin conductance response and decreases in heart rate when normally fluent speakers watched and listened to stuttered speech compared with fluent speech, suggesting that stuttering induces arousal and emotional unpleasantness in listeners. However, physiological responses of persons who stutter observing stuttering and fluent speech has not been measured. Research suggests that the mechanism responsible for listeners' reactions is the mirror neuron system. The mirror neuron system activates when perceiving and producing goal-directed actions and forms the link between action perception and action production. AIMS: To compare physiological responses elicited via fluent and stuttered speech in fluent and persons who stutter groups. METHODS & PROCEDURES: Participants included 15 adult persons who stutter (mean age = 29.7 years) and 21 normally fluent controls (mean age = 23.7 years). Participants watched and listened to six speech samples read by three persons who stutter speakers and three fluent speakers, while their skin conductance response and heart rate were recorded simultaneously. Participants' responses to each speech sample were defined as changes in mean heart rate and mean skin conductance response between 15 s before and 15 s during stimuli presentation. OUTCOMES & RESULTS: Both groups showed similar patterns of response: skin conductance response was significantly increased and heart rate was significantly decreased in response to stuttered versus fluent speech. Similar to previous findings, the highest skin conductance response measures were induced by the first presentation of stuttered speech, with the response attenuating on subsequent presentations, while the heart rate was stable over time. CONCLUSIONS & IMPLICATIONS: Results confirmed past research that showed arousal and emotional unpleasantness when observing stuttering. Clinically, these results acknowledge the arousal and emotional discomfort in fluent speakers and persons who stutter. The physiological responses to stuttering and the underlying emotional aspects should be discussed in the therapeutic milieu with notions about coping strategies.

Gaze aversion to stuttered speech: a pilot study investigating differential visual attention to stuttered and fluent speech.

BACKGROUND: People who stutter are often acutely aware that their speech disruptions, halted communication, and aberrant struggle behaviours evoke reactions in communication partners. Considering that eye gaze behaviours have emotional, cognitive, and pragmatic overtones for communicative interactions and that previous studies have indicated increased physiological arousal in listeners in response to stuttering, it was hypothesized that stuttered speech incurs increased gaze aversion relative to fluent speech. The possible importance in uncovering these visible reactions to stuttering is that they may contribute to the social penalty associated with stuttering. AIMS: To compare the eye gaze responses of college students while observing and listening to fluent and severely stuttered speech samples produced by the same adult male who stutters. METHODS & PROCEDURES: Twelve normally fluent adult college students watched and listened to three 20-second audio-video clips of the face of an adult male stuttering and three 20-second clips of the same male producing fluent speech. Their pupillary movements were recorded with an eye-tracking device and mapped to specific regions of interest (that is, the eyes, the nose and the mouth of the speaker). OUTCOMES & RESULTS: Participants spent 39% more time fixating on the speaker's eyes while witnessing fluent speech compared with stuttered speech. In contrast, participants averted their direct eye gaze more often and spent 45% more time fixating on the speaker's nose when witnessing stuttered speech compared with fluent speech. These relative time differences occurred as a function of the number of fixations in each area of interest. Thus, participants averted their gaze from the eyes of the speaker more frequently during the stuttered stimuli than the fluent stimuli. CONCLUSIONS & IMPLICATIONS: This laboratory study provides pilot data suggesting that gaze aversion is a salient response to the breakdown in communication that occurs during stuttering. This response may occur as a result of emotional, cognitive, and pragmatic factors in communication partners. Regardless of the factors contributing to the response, its primary importance may be that gaze aversion is a visible communication partner signal informing the person stuttering that something is amiss in the interaction and hence, may contribute to inducing negative emotions in the persons stuttering, via engagement of the mirror neuron system. We suggest that witnessing and interpreting communication partner responses to stuttering may play a role when a person who stutters engages in future interactions, perhaps contributing to the development of covert strategies to hide stuttering.

Comparisons of stuttering frequency during and after speech initiation in unaltered feedback, altered auditory feedback and choral speech conditions.

BACKGROUND: Stuttering is prone to strike during speech initiation more so than at any other point in an utterance. The use of auditory feedback (AAF) has been found to produce robust decreases in the stuttering frequency by creating an electronic rendition of choral speech (i.e., speaking in unison). However, AAF requires users to self-initiate speech before it can go into effect and, therefore, it might not be as helpful as true choral speech during speech initiation. AIMS: To examine how AAF and choral speech differentially enhance fluency during speech initiation and in subsequent portions of utterances. METHODS & PROCEDURES: Ten participants who stuttered read passages without altered feedback (NAF), under four AAF conditions and under a true choral speech condition. Each condition was blocked into ten 10 s trials separated by 5 s intervals so each trial required 'cold' speech initiation. In the first analysis, comparisons of stuttering frequencies were made across conditions. A second, finer grain analysis involved examining stuttering frequencies on the initial syllable, the subsequent four syllables produced and the five syllables produced immediately after the midpoint of each trial. OUTCOMES & RESULTS: On average, AAF reduced stuttering by approximately 68% relative to the NAF condition. Stuttering frequencies on the initial syllables were considerably higher than on the other syllables analysed (0.45 and 0.34 for NAF and AAF conditions, respectively). After the first syllable was produced, stuttering frequencies dropped precipitously and remained stable. However, this drop in stuttering frequency was significantly greater (approximately 84%) in the AAF conditions than in the NAF condition (approximately 66%) with frequencies on the last nine syllables analysed averaging 0.15 and 0.05 for NAF and AAF conditions, respectively. In the true choral speech condition, stuttering was virtually (approximately 98%) eliminated across all utterances and all syllable positions. CONCLUSIONS & IMPLICATIONS: Altered auditory feedback effectively inhibits stuttering immediately after speech has been initiated. However, unlike a true choral signal, which is exogenously initiated and offers the most complete fluency enhancement, AAF requires speech to be initiated by the user and 'fed back' before it can directly inhibit stuttering. It is suggested that AAF can be a viable clinical option for those who stutter and should often be used in combination with therapeutic techniques, particularly those that aid speech initiation. The substantially higher rate of stuttering occurring on initiation supports a hypothesis that overt stuttering events help 'release' and 'inhibit' central stuttering blocks. This perspective is examined in the context of internal models and mirror neurons.

Jobs, sex, love and lifestyle: when nonstutterers assume the roles of stutterers.

PURPOSE: This study assessed the impact of stuttering via a questionnaire in which fluent individuals were asked to assume the mindset of persons who stutter (PWS) in various life aspects, including vocation, romance, daily activities, friends/social life, family and general lifestyle. The perceived impact of stuttering through the mind's eyes of nonstutterers is supposed to reflect respondents' abilities to impart 'theory of mind' in addressing social penalties related to stuttering. METHOD: Ninety-one university students answered a questionnaire containing 56 statements on a 7-point Likert scale. Forty-four participants (mean age = 20.4, SD = 4.4) were randomly selected to assume a stuttering identity and 47 respondents (mean age = 20.5, SD = 3.1) to assume their normally fluent identity. RESULTS: Significant differences between groups were found in more than two thirds of items regarding employment, romance, and daily activities, and in fewer than half of items regarding family, friend/social life, and general life style (p <0.001). CONCLUSIONS: The social penalties associated with stuttering appear to be apparent to fluent individuals, especially in areas of vocation, romance, and daily activities, suggesting that nonstuttering individuals, when assuming the role of PWS, are capable of at least temporarily feeling the negative impact of stuttering.

Sex differences in early sensorimotor processing for speech discrimination.

Sensorimotor activity in speech perception tasks varies as a function of context, cognitive load, and cognitive ability. This study investigated listener sex as an additional variable. Raw EEG data were collected as 21 males and 21 females discriminated /ba/ and /da/ in quiet and noisy backgrounds. Independent component analyses of data from accurately discriminated trials identified sensorimotor mu components with characteristic alpha and beta peaks from 16 members of each sex. Time-frequency decompositions showed that in quiet discrimination, females displayed stronger early mu-alpha synchronization, whereas males showed stronger mu-beta desynchronization. Findings indicate that early attentional mechanisms for speech discrimination were characterized by sensorimotor inhibition in females and predictive sensorimotor activation in males. Both sexes showed stronger early sensorimotor inhibition in noisy discrimination conditions versus in quiet, suggesting sensory gating of the noise. However, the difference in neural activation between quiet and noisy conditions was greater in males than females. Though sex differences appear unrelated to behavioral accuracy, they suggest that males and females exhibit early sensorimotor processing for speech discrimination that is fundamentally different, yet similarly adaptable to adverse conditions. Findings have implications for understanding variability in neuroimaging data and the male prevalence in various neurodevelopmental disorders with inhibitory dysfunction.

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

Deficits in basal ganglia-based inhibitory and timing circuits along with sensorimotor internal modeling mechanisms are thought to underlie stuttering. However, much remains to be learned regarding the precise manner how these deficits contribute to disrupting both speech and cognitive functions in those who stutter. Herein, we examine the suitability of electroencephalographic (EEG) mu rhythms for addressing these deficits. We review some previous findings of mu rhythm activity differentiating stuttering from non-stuttering individuals and present some new preliminary findings capturing stuttering-related deficits in working memory. Mu rhythms are characterized by spectral peaks in alpha (8-13 Hz) and beta (14-25 Hz) frequency bands (mu-alpha and mu-beta). They emanate from premotor/motor regions and are influenced by basal ganglia and sensorimotor function. More specifically, alpha peaks (mu-alpha) are sensitive to basal ganglia-based inhibitory signals and sensory-to-motor feedback. Beta peaks (mu-beta) are sensitive to changes in timing and capture motor-to-sensory (i.e., forward model) projections. Observing simultaneous changes in mu-alpha and mu-beta across the time-course of specific events provides a rich window for observing neurophysiological deficits associated with stuttering in both speech and cognitive tasks and can provide a better understanding of the functional relationship between these stuttering symptoms. We review how independent component analysis (ICA) can extract mu rhythms from raw EEG signals in speech production tasks, such that changes in alpha and beta power are mapped to myogenic activity from articulators. We review findings from speech production and auditory discrimination tasks demonstrating that mu-alpha and mu-beta are highly sensitive to capturing sensorimotor and basal ganglia deficits associated with stuttering with high temporal precision. Novel findings from a non-word repetition (working memory) task are also included. They show reduced mu-alpha suppression in a stuttering group compared to a typically fluent group. Finally, we review current limitations and directions for future research.

Sensorimotor activity measured via oscillations of EEG mu rhythms in speech and non-speech discrimination tasks with and without segmentation demands.

Better understanding of the role of sensorimotor processing in speech and non-speech segmentation can be achieved with more temporally precise measures. Twenty adults made same/different discriminations of speech and non-speech stimuli pairs, with and without segmentation demands. Independent component analysis of 64-channel EEG data revealed clear sensorimotor mu components, with characteristic alpha and beta peaks, localized to premotor regions in 70% of participants.Time-frequency analyses of mu components from accurate trials showed that (1) segmentation tasks elicited greater event-related synchronization immediately following offset of the first stimulus, suggestive of inhibitory activity; (2) strong late event-related desynchronization in all conditions, suggesting that working memory/covert replay contributed substantially to sensorimotor activity in all conditions; (3) stronger beta desynchronization in speech versus non-speech stimuli during stimulus presentation, suggesting stronger auditory-motor transforms for speech versus non-speech stimuli. Findings support the continued use of oscillatory approaches for helping understand segmentation and other cognitive tasks.

Trait related sensorimotor deficits in people who stutter: An EEG investigation of µ rhythm dynamics during spontaneous fluency.

Stuttering is associated with compromised sensorimotor control (i.e., internal modeling) across the dorsal stream and oscillations of EEG mu (µ) rhythms have been proposed as reliable indices of anterior dorsal stream processing. The purpose of this study was to compare µ rhythm oscillatory activity between (PWS) and matched typically fluent speakers (TFS) during spontaneously fluent overt and covert speech production tasks. Independent component analysis identified bilateral µ components from 24/27 PWS and matched TFS that localized over premotor cortex. Time-frequency analysis of the left hemisphere µ clusters demonstrated significantly reduced µ-α and µ-ß ERD (pCLUSTER < 0.05) in PWS across the time course of overt and covert speech production, while no group differences were found in the right hemisphere in any condition. Results were interpreted through the framework of State Feedback Control. They suggest that weak forward modeling and evaluation of sensory feedback across the time course of speech production characterizes the trait related sensorimotor impairment in PWS. This weakness is proposed to represent an underlying sensorimotor instability that may predispose the speech of PWS to breakdown.

The Effects of Fluency Enhancing Conditions on Sensorimotor Control of Speech in Typically Fluent Speakers: An EEG Mu Rhythm Study.

Objective: To determine whether changes in sensorimotor control resulting from speaking conditions that induce fluency in people who stutter (PWS) can be measured using electroencephalographic (EEG) mu rhythms in neurotypical speakers. Methods: Non-stuttering (NS) adults spoke in one control condition (solo speaking) and four experimental conditions (choral speech, delayed auditory feedback (DAF), prolonged speech and pseudostuttering). Independent component analysis (ICA) was used to identify sensorimotor µ components from EEG recordings. Time-frequency analyses measured µ-alpha (8-13 Hz) and µ-beta (15-25 Hz) event-related synchronization (ERS) and desynchronization (ERD) during each speech condition. Results: 19/24 participants contributed µ components. Relative to the control condition, the choral and DAF conditions elicited increases in µ-alpha ERD in the right hemisphere. In the pseudostuttering condition, increases in µ-beta ERD were observed in the left hemisphere. No differences were present between the prolonged speech and control conditions. Conclusions: Differences observed in the experimental conditions are thought to reflect sensorimotor control changes. Increases in right hemisphere µ-alpha ERD likely reflect increased reliance on auditory information, including auditory feedback, during the choral and DAF conditions. In the left hemisphere, increases in µ-beta ERD during pseudostuttering may have resulted from the different movement characteristics of this task compared with the solo speaking task. Relationships to findings in stuttering are discussed. Significance: Changes in sensorimotor control related feedforward and feedback control in fluency-enhancing speech manipulations can be measured using time-frequency decompositions of EEG µ rhythms in neurotypical speakers. This quiet, non-invasive, and temporally sensitive technique may be applied to learn more about normal sensorimotor control and fluency enhancement in PWS.

On the importance of scientific rhetoric in stuttering: a reply to Finn, Bothe, and Bramlett (2005).

PURPOSE: To refute the alleged practice of "pseudoscience" by P. Finn, A. K. Bothe, and R. E. Bramlett (2005) and to illustrate their experimental and systematic bias when evaluating the SpeechEasy, an altered auditory feedback device used in the management of stuttering. METHOD: We challenged the experimental design that led to the seemingly predetermined outcome of pseudoscience rather than science: Limited preselected literature was submitted to a purposely sampled panel of judges (i.e., their own students). Each criterion deemed pseudoscientific was contested with published peer-reviewed data illustrating the importance of good rhetoric, testability, and logical outcomes from decades of scientific research. CONCLUSIONS: Stuttering is an involuntary disorder that is highly resistant to therapy. Altered auditory feedback is a derivation of choral speech (nature's most powerful stuttering "inhibitor") that can be synergistically combined with other methods for optimal stuttering inhibition. This approach is logical considering that in stuttering no single treatment is universally helpful. Also, caution is suggested when attempting to differentiate science from pseudoscience in stuttering treatments using the criteria employed by Finn et al. For example, evaluating behavioral therapy outcomes implements a post hoc or untestable system. Speech outcome (i.e., stuttered or fluent speech) determines success or failure of technique use, placing responsibility for failure on those who stutter.

The perceived impact of stuttering on personality as measured by the NEO-FFI-3.

The NEO-FFI has been widely used to demonstrate personality differences between people who stutter (PWS) and those who do not. These differences can be interpreted as indicators of internal sources of disability that contribute to handicaps associated with stuttering. The aim of the current study was to use this same tool to determine the perceived impact of stuttering on personality in order to provide a similar indicator of how external factors may contribute to the stuttering disability. A total of 49 non-stuttering young adults were given the NEO-FFI-3 after watching a video of someone stuttering (moderately to severely) and after watching a video of someone speaking fluently. Participants were asked to answer test items while imagining that they had spoken like the persons in the videos for their entire lives. When asked to assume the stuttering perspective, participants reported themselves to be significantly more neurotic (P < 0.01) and less extraverted (P < 0.01) than when they assumed the perspective of the fluent speaker. The large differences (∼10 points; greater than one standard deviation) in these domains between the fluent and stuttered perspectives are consistent with existing stereotypes about PWS. These differences are greater than and only partially consistent with differences in personality found between PWS and non-stuttering individuals. The findings support the notion that external factors (e.g. listener reactions and stereotypes about PWS) contribute strongly to the manner in which stuttering restricts function and results in handicaps.