Examining resting state functional connectivity and frequency power analysis in adults who stutter compared to adults who do not stutter

Introduction

Stuttering is a speech disorder characterized by impaired connections between brain regions involved in speech production. This study aimed to investigate functional connectivity and frequency power during rest in adults who stutter (AWS) compared to fluent adults (AWNS) in the dorsolateral prefrontal cortex (DLPFC), dorsolateral frontal cortex (DLFC), supplementary motor area (SMA), motor speech, angular gyrus (AG), and inferior temporal gyrus (ITG).

Materials and methods

Fifteen AWS (3 females, 12 males) and fifteen age- and sex-matched AWNS (3 females, 12 males) participated in this study. All participants were native Persian speakers. Stuttering severity in the AWS group was assessed using the Persian version of the Stuttering Severity Instrument Fourth Edition (SSI-4). Resting-state electroencephalography (EEG) was recorded for 5 min while participants sat comfortably with their eyes open. We analyzed frequency band power across various frequency bands and investigated functional connectivity within the specified speech region.

Results

Significant between-group differences were found in band powers including alpha, beta, delta, theta, and gamma, specifically in the premotor, SMA, motor speech, and frontal regions. AWS also showed increased coherence between the right motor speech region compared to controls. We demonstrate that the proposed hierarchical false discovery rate (FDR) method is the most effective for both simulations and experimental data. In the expected regions, this method revealed significant synchrony effects at an acceptable error rate of 5%.

Conclusion

The results highlight disrupted functional connectivity in AWS at resting state, particularly in speech-related and associated areas. Given the complex neurological basis of developmental stuttering, robust neural markers are closely linked to this phenomenon. These markers include imbalanced activity within brain regions associated with speech and motor functions, coupled with impaired functional connectivity between these regions. The cortico-basal ganglia-thalamo-cortical system governs the dynamic interplay between cortical regions, with SMA as a key cortical site. It is hypothesized that the aberrant resting state functional connectivity will impact the language planning and motor execution necessary for fluent speech. Examining resting-state metrics as biomarkers could further elucidate the neural underpinnings of stuttering and guide intervention.

Vocal Tract Discomforts among Smokers

INTRODUCTION

Smoking is a dangerous behavior for the human body and the vocal tract. Smoking can cause several laryngeal and vocal tract symptoms in smokers. One of these symptoms can be physical discomfort experienced by this population. Therefore, the aim of the present study was to investigate vocal tract discomfort (VTD) in smokers compared to healthy non-smoker participants.

MATERIALS AND METHODS

The smokers group was forty-eight men with a mean age of 47.54 ± 9.21 years, and the matched non-smokers group was 48 men with a mean age of 44.88 ± 10.81 years. The participants underwent vocal tract discomfort assessment using the Persian version of the VTD scale. Statistical Package for the Social Science (SPSS) was used for statistical analysis and the Mann-Whitney U test was used to compare variables between groups.

RESULTS

The smokers more frequently had VTD symptoms (P < 0.05) than non-smokers for all items of the VTD scale with the exception of aches. Also, smokers had more significant VTD severity in all items than non-smokers (P < 0.05). Moreover, there were significant statistical differences between the total score of both frequency and severity of VTD between smokers and non-smokers. The most to the least VTD symptoms in smokers were irritation, sore, tickling, burning, tightness, lump in the throat, dry, and aching symptoms, respectively.

CONCLUSION

The present study suggests that smoking can cause more physical vocal tract discomfort in smokers compared to non-smokers. These results can inform future research and interventions in the smoker population.

A comparison of the performance of Persian speaking children who do and do not stutter on three nonwords repetition tasks

PURPOSE

The purpose of the study was to examine the performance of Persian speaking children who stutter (CWS) and children who do not stutter (CWNS) on three nonword repetition tasks, while also focusing on which task and scoring method best differentiates the two groups of children.

METHOD

Thirty CWS and 30 CWNS between the ages of 5;0 to 6;6 completed three nonword repetition tasks that varied in complexity. Each task was scored using two methods: nonwords correct and phonemes correct. Between-group differences in performance on each task were examined, along with disfluencies for CWS and the task and scoring method that best differentiated the CWS and CWNS.

RESULTS

The findings revealed that, across all three nonword repetition tasks, the CWS consistently produced fewer nonwords correct and phonemes correct than the CWNS group at virtually all syllable lengths. The CWS produced more disfluencies on longer nonwords than shorter nonwords in all three nonword repetition tasks. The nonword repetition task with lower wordlikeness and more phonologically complex items best differentiated the two groups of children. Findings further revealed that discriminative accuracy was highest for scoring based on the number of phonemes produced correctly.

CONCLUSION

Findings provide further evidence to suggest that CWS may have difficulty with phonological working memory and/or phonological processing.