No evidence of altered language laterality in people who stutter across different brain imaging studies of speech and language

A long-standing neurobiological explanation of stuttering is the incomplete cerebral dominance theory, which refers to competition between two hemispheres for ‘dominance’ over handedness and speech, causing altered language lateralization. Renewed interest in these ideas came from brain imaging findings in people who stutter of increased activity in the right hemisphere during speech production or of shifts in activity from right to left when fluency increased. Here, we revisited this theory using functional MRI data from children and adults who stutter, and typically fluent speakers (119 participants in total) during four different speech and language tasks: overt sentence reading, overt picture description, covert sentence reading and covert auditory naming. Laterality indices were calculated for the frontal and temporal lobes using the laterality index toolbox running in Statistical Parametric Mapping. We also repeated the analyses with more specific language regions, namely the pars opercularis (Brodmann area 44) and pars triangularis (Brodmann area 45). Laterality indices in people who stutter and typically fluent speakers did not differ, and Bayesian analyses provided moderate to anecdotal levels of support for the null hypothesis (i.e. no differences in laterality in people who stutter compared with typically fluent speakers). The proportions of the people who stutter and typically fluent speakers who were left lateralized or had atypical rightward or bilateral lateralization did not differ. We found no support for the theory that language laterality is reduced or differs in people who stutter compared with typically fluent speakers

Facilitation of motor excitability during listening to spoken sentences is not modulated by noise or semantic coherence

Comprehending speech can be particularly challenging in a noisy environment and in the absence of semantic context. It has been proposed that the articulatory motor system would be recruited especially in difficult listening conditions. However, it remains unknown how signal-to-noise ratio (SNR) and semantic context affect the recruitment of the articulatory motor system when listening to continuous speech. The aim of the present study was to address the hypothesis that involvement of the articulatory motor cortex increases when the intelligibility and clarity of the spoken sentences decreases, because of noise and the lack of semantic context. We applied Transcranial Magnetic Stimulation (TMS) to the lip and hand representations in the primary motor cortex and measured motor evoked potentials from the lip and hand muscles, respectively, to evaluate motor excitability when young adults listened to sentences. In Experiment 1, we found that the excitability of the lip motor cortex was facilitated during listening to both semantically anomalous and coherent sentences in noise relative to non-speech baselines, but neither SNR nor semantic context modulated the facilitation. In Experiment 2, we replicated these findings and found no difference in the excitability of the lip motor cortex between sentences in noise and clear sentences without noise. Thus, our results show that the articulatory motor cortex is involved in speech processing even in optimal and ecologically valid listening conditions and that its involvement is not modulated by the intelligibility and clarity of speech

The effects of delayed auditory and visual feedback on speech production

Monitoring the sensory consequences of articulatory movements supports speaking. For example, delaying auditory feedback of a speaker's voice disrupts speech production. Also, there is evidence that this disruption may be decreased by immediate visual feedback, i.e., seeing one's own articulatory movements. It is, however, unknown whether delayed visual feedback affects speech production in fluent speakers. Here, the effects of delayed auditory and visual feedback on speech fluency (i.e., speech rate and errors), vocal control (i.e., intensity and pitch), and speech rhythm were investigated. Participants received delayed (by 200 ms) or immediate auditory feedback, while repeating sentences. Moreover, they received either no visual feedback, immediate visual feedback, or delayed visual feedback (by 200, 400, and 600 ms). Delayed auditory feedback affected fluency, vocal control, and rhythm. Immediate visual feedback had no effect on any of the speech measures when it was combined with delayed auditory feedback. Delayed visual feedback did, however, affect speech fluency when it was combined with delayed auditory feedback. In sum, the findings show that delayed auditory feedback disrupts fluency, vocal control, and rhythm and that delayed visual feedback can strengthen the disruptive effect of delayed auditory feedback on fluency

Planum temporale asymmetry in people who stutter

Previous studies have reported that the planum temporale - a language-related structure that normally shows a leftward asymmetry - had reduced asymmetry in people who stutter (PWS) and reversed asymmetry in those with severe stuttering. These findings are consistent with the theory that altered language lateralization may be a cause or consequence of stuttering. Here, we re-examined these findings in a larger sample of PWS. We evaluated planum temporale asymmetry in structural MRI scans obtained from 67 PWS and 63 age-matched controls using: 1) manual measurements of the surface area; 2) voxel-based morphometry to automatically calculate grey matter density. We examined the influences of gender, age, and stuttering severity on planum temporale asymmetry. The size of the planum temporale and its asymmetry were not different in PWS compared with Controls using either the manual or the automated method. Both groups showed a significant leftwards asymmetry on average (about one-third of PWS and Controls showed rightward asymmetry). Importantly, and contrary to previous reports, the degree of asymmetry was not related to stuttering severity. In the manual measurements, women who stutter had a tendency towards rightwards asymmetry but men who stutter showed the same degree of leftwards asymmetry as male Controls. In the automated measurements, Controls showed a significant increase in leftwards asymmetry with age but this relationship was not observed in PWS. We conclude that reduced planum temporale asymmetry is not a prominent feature of the brain in PWS and that the asymmetry is unrelated to stuttering severity. [Abstract copyright: Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Investigating the feasibility of using transcranial direct current stimulation to enhance fluency in people who stutter

Developmental stuttering is a disorder of speech fluency affecting 1% of the adult population. Long-term reductions in stuttering are difficult for adults to achieve with behavioural therapies. We investigated whether a single session of transcranial direct current stimulation (TDCS) could improve fluency in people who stutter (PWS). In separate sessions, either anodal TDCS (1 mA for 20 min) or sham stimulation was applied over the left inferior frontal cortex while PWS read sentences aloud. Fluency was induced during the stimulation period by using choral speech, that is, participants read in unison with another speaker. Stuttering frequency during sentence reading, paragraph reading and conversation was measured at baseline and at two outcome time points: immediately after the stimulation period and 1 h later. Stuttering was reduced significantly at both outcome time points for the sentence-reading task, presumably due to practice, but not during the paragraph reading or conversation tasks. None of the outcome measures were significantly modulated by anodal TDCS. Although the results of this single-session study showed no significant TDCS-induced improvements in fluency, there were some indications that further research is warranted. We discuss factors that we believe may have obscured the expected positive effects of TDCS on fluency, such as heterogeneity in stuttering severity for the sample and variations across sessions. Consideration of such factors may inform future studies aimed at determining the potential of TDCS in the treatment of developmental stuttering

‘La Beauté’: Art and Dialogism in the Poetry of Baudelaire

Studies of Baudelaire’s poem ‘La Beauté’ have generally agreed that it has a key role to play in our understanding of his aesthetic theories, but have differed wildly in how this role is interpreted. The present study brings together arguments that see the speaker of the poem, Beauty, as a statue, along with those that understand the poem as being fundamentally ironic. Situating ‘La Beauté’ in the context of Baudelaire’s art criticism allows us to understand it as part of his engagement in debates within the visual arts. This gives us a new reading of Beauty’s claims as voicing the positions of neo-classical idealism, and specifically those of nineteenth-century academic theorists influenced by the eighteenth-century German inventor of art history, Winckelmann. Recognizing the importance of Winckelmann in approaching this poem sheds light on the rejection of movement and emotion that is pronounced by Beauty, and which contradict Baudelaire’s theoretical positions expressed elsewhere. The sonnet is thus incorporating the language of a speaker who is distinct from the lyric ‘je’ and cannot be reduced to a mask for him or a part of his divided self. This language and the position it expresses are framed within the sonnet, whose implicit irony leads to what Bakhtin calls double voicing. This approach offers a new reading of ‘La Beauté’ in formal terms as an example of Bakhtinian dialogism within lyric poetry

Predicting Risk of Serious Bacterial Infections in Febrile Children in the Emergency Department

BACKGROUND: Improving the diagnosis of serious bacterial infections (SBIs) in the children's emergency department is a clinical priority. Early recognition reduces morbidity and mortality, and supporting clinicians in ruling out SBIs may limit unnecessary admissions and antibiotic use. METHODS: A prospective, diagnostic accuracy study of clinical and biomarker variables in the diagnosis of SBIs (pneumonia or other SBI) in febrile children <16 years old. A diagnostic model was derived by using multinomial logistic regression and internally validated. External validation of a published model was undertaken, followed by model updating and extension by the inclusion of procalcitonin and resistin. RESULTS: There were 1101 children studied, of whom 264 had an SBI. A diagnostic model discriminated well between pneumonia and no SBI (concordance statistic 0.84, 95% confidence interval 0.78-0.90) and between other SBIs and no SBI (0.77, 95% confidence interval 0.71-0.83) on internal validation. A published model discriminated well on external validation. Model updating yielded good calibration with good performance at both high-risk (positive likelihood ratios: 6.46 and 5.13 for pneumonia and other SBI, respectively) and low-risk (negative likelihood ratios: 0.16 and 0.13, respectively) thresholds. Extending the model with procalcitonin and resistin yielded improvements in discrimination. CONCLUSIONS: Diagnostic models discriminated well between pneumonia, other SBIs, and no SBI in febrile children in the emergency department. Improvements in the classification of nonevents have the potential to reduce unnecessary hospital admissions and improve antibiotic prescribing. The benefits of this improved risk prediction should be further evaluated in robust impact studies

Household Structure and Housework Hours: The Effect of Women's Changing Labour Force Participation on the Domestic Division of Labour

In this thesis, I examine the relationships between changes in the structure of Australian families, trends in gender attitudes and trends in the housework hours of men and women in couple families. I examine how changing patterns of family formation and labour force participation are affecting patterns of time allocated to housework. Women’s responsibility for housework affects their ability to compete on equal terms with men in the labour market. Using data collected by three national surveys conducted in 1986, 1993 and 2005 I examine whether there is any evidence of convergence in the type of housework that men and women do (task convergence) and in the amount of time men and women spend doing housework (time convergence). I am primarily interested in whether Australian men are spending more time doing core housework tasks, namely cooking, cleaning and laundry. Tracking change over time in the US and the UK, researchers have found that there has been an increase in the amount of time men spent doing core housework tasks, however, there has been no evidence of a similar trend here in Australia. I review the key theoretical perspectives underpinning research into the gender division of labour: time availability, exchange of economic resources, gender and socialisation, before employing measures of the first three of these perspectives to examine change over time in the housework hours of men and women. The data analysed for this study do not include adequate measures of socialisation, therefore, I do not examine the association between socialisation and housework hours. Although previous researchers have examined the division of domestic labour within couple families, I focus on within gender comparisons examining the housework hours of men and women in various family types. By examining the absolute housework hours rather than the relative housework hours of men and women, I can determine whether men and women are spending a similar proportion of their housework hours doing particular tasks and whether the amount of time men and women spend doing particular tasks has become more similar. The division of housework into female tasks and male tasks is a major barrier to a more equal division of labour. Tasks traditionally regarded as female tasks- meal preparation, doing the dishes, cleaning the house, doing the laundry and shopping for groceries- account for the bulk of household labour and need to be completed on a regular, sometimes daily, basis. On the other hand, tasks traditionally regarded as male tasks- taking out the garbage, mowing the lawn, gardening and home repairs and maintenance- are more discretionary and can be completed on a more flexible schedule. Unless the division of tasks into male tasks and female tasks becomes less rigid, women will continue to spend more time doing housework than men. Overall, I find evidence of convergence in both housework tasks and housework hours. In 2005, men spent a larger proportion and women spent a smaller proportion of their housework time doing the core housework tasks compared to their counterparts in 1986. There is also evidence that the amount of time men spent doing housework increased and the amount of time women spent doing housework decreased. Men spent more time doing both female and male housework tasks and women spent less time doing female housework tasks and more time doing male housework tasks. These findings suggest that housework tasks have become more gender neutral. I also find evidence of a general trend towards a more equal division of labour with men in couple families increasing their housework hours by one and a half hours per week regardless of the employment status of their female partners and women in couple families spending less time doing housework regardless of their own employment status

Paid and unpaid Work in Australian households: Towards an understanding of the new gender division of labour

Recent changes in the labour force participation rates of men and women give rise to new questions regarding the division of labour in Australian families. Over the last few decades we have seen a marked increase in the labour force participation rates of women and a decline in the labour force participation rates of men. In the majority of households both partners are now engaged in paid employment. Our research, and that of others, has shown that these changing labour force participation rates have not automatically led to a radical reorganisation of the domestic division of labour, suggesting that women are adding their paid work hours to their unpaid work hours, effectively doing a ‘second shift’. Therefore, it is timely to consider how couples divide total work for the household, that is, the combination of paid and unpaid work. In this study, we use data collected in a 2005 national Australian survey to examine whether women in dual earner families have higher total workloads than men in dual earner families. We find that in “new traditional” households women continue to undertake a larger proportion of unpaid work. In dual full-time earner households, however the gender gap in men’s and women’s total workload is far less evident. We conclude that the second shift is most apparent in “new traditional” households. In dual full-time earner households on the other hand, there is a new gender division of labour that reflects women’s declining involvement in unpaid work and increased involvement in paid work

Transcranial direct current stimulation over left inferior frontal cortex improves speech fluency in adults who stutter

Stuttering is a neurodevelopmental condition affecting 5% of children, and persisting in 1% of adults. Promoting lasting fluency improvement in adults who stutter is a particular challenge. Novel interventions to improve outcomes are of value, therefore. Previous work in patients with acquired motor and language disorders reported enhanced benefits of behavioural therapies when paired with transcranial direct current stimulation. Here, we report the results of the first trial investigating whether transcranial direct current stimulation can improve speech fluency in adults who stutter. We predicted that applying anodal stimulation to the left inferior frontal cortex during speech production with temporary fluency inducers would result in longer-lasting fluency improvements. Thirty male adults who stutter completed a randomized, double-blind, controlled trial of anodal transcranial direct current stimulation over left inferior frontal cortex. Fifteen participants received 20 min of 1-mA stimulation on five consecutive days while speech fluency was temporarily induced using choral and metronome-timed speech. The other 15 participants received the same speech fluency intervention with sham stimulation. Speech fluency during reading and conversation was assessed at baseline, before and after the stimulation on each day of the 5-day intervention, and at 1 and 6 weeks after the end of the intervention. Anodal stimulation combined with speech fluency training significantly reduced the percentage of disfluent speech measured 1 week after the intervention compared with fluency intervention alone. At 6 weeks after the intervention, this improvement was maintained during reading but not during conversation. Outcome scores at both post-intervention time points on a clinical assessment tool (the Stuttering Severity Instrument, version 4) also showed significant improvement in the group receiving transcranial direct current stimulation compared with the sham group, in whom fluency was unchanged from baseline. We conclude that transcranial direct current stimulation combined with behavioural fluency intervention can improve fluency in adults who stutter. Transcranial direct current stimulation thereby offers a potentially useful adjunct to future speech therapy interventions for this population, for whom fluency therapy outcomes are currently limited