SAR: Speech, Language & Hearing Sciences: Scholarly Papers

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Multi-level outcomes for young adults with acquired brain injury through a remote intensive cognitive rehabilitation approach: a pilot intervention study
(Informa UK Limited, 2022-01-28) Gilbert, Christianna; Mooradian, Grace; Citorik, Anne; Gilmore, Natalie; Kiran, Swathi
OBJECTIVE: To investigate the effects of the Intensive Cognitive and Communication Rehabilitation (ICCR) program for young adults with acquired brain injury (ABI) using a quasi-experimental pilot intervention study design while transitioning to remote implementation. METHOD: Twelve young adults with chronic ABI (treatment n = 7; control n = 5) participated in ICCR (i.e., lectures, seminars, individual cognitive rehabilitation (CR), technology training) for six hours/day, four days/week, for one or two 12-week semesters. Outcomes included classroom metrics, individual therapy performance, including Goal Attainment Scaling (GAS), standardized cognitive-linguistic assessments, and participation and health-related quality of life (QOL) measures. RESULTS: In the first semester (in-person and remote), treatment participants significantly improved in classroom exams; individual therapy (i.e., memory, writing, GAS); executive function and participation measures, but not QOL. In the second semester (remote), treatment participants significantly improved in classroom exams; essay writing; individual therapy (i.e., writing and GAS); and memory assessment, but not in participation or QOL. Treatment participants enrolled in consecutive semesters significantly improved in classroom exams, individual therapy (i.e., memory), participation and QOL, but not on standardized cognitive assessments. Controls demonstrated no significant group-level gains. CONCLUSION: These preliminary results highlight the benefit of intensive, integrated, and contextualized CR for this population and show promise for its remote delivery.
Representation of semantic typicality in brain activation in healthy adults and individuals with aphasia: a multi-voxel pattern analysis
(2021-07-30) Li, Ran; Perrachione, Tyler K.; Tourville, Jason A.; Kiran, Swathi
This study aimed to investigate brain regions that show different activation patterns between semantically typical and atypical items in both healthy adults and individuals with aphasia (PWA). Eighteen neurologically healthy adults and twenty-one PWA participated in an fMRI semantic feature verification task that included typical and atypical stimuli from five different semantic categories. A whole-brain searchlight multi-voxel pattern analysis (MVPA) was conducted to classify brain activation patterns between typical and atypical conditions in each participant group separately. Behavioral responses were faster and more accurate for typical vs. atypical items across both groups. The searchlight MVPA identified two significant clusters in healthy adults: left middle occipital gyrus and right calcarine cortex, but no significant clusters were found in PWA. A follow-up analysis in PWA revealed a significant association between neural classification of semantic typicality in the left middle occipital gyrus and reaction times in the fMRI task. When the typicality effect was examined for each semantic category at the univariate level, significance was identified in the visual cortex for fruits in both groups of participants. These findings suggest that semantic typicality was modulated in the visual cortex in healthy individuals, but to a lesser extent in the same region in PWA.
An ode to fetal, infant, and toddler neuroimaging: chronicling early clinical to research applications with MRI, and an introduction to an academic society connecting the field
(2022-04) Pollatou, Angeliki; Filippi, Courtney A.; Aydin, Ezra; Vaughn, Kelly; Thompson, Deanne; Korom, Marta; Dufford, Alexander J.; Howell, Brittany; Zöllei, Lilla; Martino, Adriana Di; Graham, Alice; FIT’NG Group; Scheinost, Dustin; Spann, Marisa N.
Fetal, infant, and toddler neuroimaging is commonly thought of as a development of modern times (last two decades). Yet, this field mobilized shortly after the discovery and implementation of MRI technology. Here, we provide a review of the parallel advancements in the fields of fetal, infant, and toddler neuroimaging, noting the shifts from clinical to research use, and the ongoing challenges in this fast-growing field. We chronicle the pioneering science of fetal, infant, and toddler neuroimaging, highlighting the early studies that set the stage for modern advances in imaging during this developmental period, and the large-scale multi-site efforts which ultimately led to the explosion of interest in the field today. Lastly, we consider the growing pains of the community and the need for an academic society that bridges expertise in developmental neuroscience, clinical science, as well as computational and biomedical engineering, to ensure special consideration of the vulnerable mother-offspring dyad (especially during pregnancy), data quality, and image processing tools that are created, rather than adapted, for the young brain.
Dear reviewers: responses to common reviewer critiques about infant neuroimaging studies
(2022-02) Korom, Marta; Camacho, M.Catalina; Filippi, Courtney A.; Licandro, Roxane; Moore, Lucille A.; Dufford, Alexander J.; Zöllei, Lilla; Graham, Alice M.; Spann, Marisa; Howell, Brittany; FIT’NG; Shultz, Sarah; Scheinost, Dustin
The field of adult neuroimaging relies on well-established principles in research design, imaging sequences, processing pipelines, as well as safety and data collection protocols. The field of infant magnetic resonance imaging, by comparison, is a young field with tremendous scientific potential but continuously evolving standards. The present article aims to initiate a constructive dialog between researchers who grapple with the challenges and inherent limitations of a nascent field and reviewers who evaluate their work. We address 20 questions that researchers commonly receive from research ethics boards, grant, and manuscript reviewers related to infant neuroimaging data collection, safety protocols, study planning, imaging sequences, decisions related to software and hardware, and data processing and sharing, while acknowledging both the accomplishments of the field and areas of much needed future advancements. This article reflects the cumulative knowledge of experts in the FIT'NG community and can act as a resource for both researchers and reviewers alike seeking a deeper understanding of the standards and tradeoffs involved in infant neuroimaging.
Cycling exercise classes may be bad for your (hearing) health
(2017-08) Sinha, Sumi; Kozin, Elliot D.; Naunheim, Matthew R.; Barber, Samuel R.; Wong, Kevin; Katz, Leanna W.; Otero, Tiffany M.N.; Stefanov-Wagner, Ishmael J.M.; Remenschneider, Aaron K.
OBJECTIVES/HYPOTHESIS: 1) Determine feasibility of smartphone-based mobile technology to measure noise exposure; and 2) measure noise exposure in exercise spin classes. STUDY DESIGN: Observational Study. METHODS: The SoundMeter Pro app (Faber Acoustical, Salt Lake City, UT) was installed and calibrated on iPhone and iPod devices in an audiology chamber using an external sound level meter to within 2 dBA of accuracy. Recording devices were placed in the bike cupholders of participants attending spin classes in Boston, Massachusetts (n = 17) and used to measure sound level (A-weighted) and noise dosimetry during exercise according to National Institute for Occupational Safety and Health (NIOSH) guidelines. RESULTS: The average length of exposure was 48.9 ± 1.2 (standard error of the mean) minutes per class. Maximum sound recorded among 17 random classes was 116.7 dBA, which was below the NIOSH instantaneous exposure guideline of 140 dBA. An average of 31.6 ± 3.8 minutes were spent at >100 dBA. This exceeds NIOSH recommendations of 15 minutes of exposure or less at 100 dBA per day. Average noise exposure for one 45-minute class was 8.95 ± 1.2 times the recommended noise exposure dose for an 8-hour workday. CONCLUSIONS: Preliminary data shows that randomly sampled cycling classes may have high noise levels with a potential for noise-induced hearing loss. Mobile dosimetry technology may enable users to self-monitor risk to their hearing and actively engage in noise protection measures. LEVEL OF EVIDENCE: NA Laryngoscope, 127:1873-1877, 2017.
A scoping review of literature using speech recognition technologies by individuals with disabilities in multiple contexts
(2021-10-20) Berner, Kevin; Alves, Alana N.
PURPOSE: Speech recognition technology (SRT) is increasingly available and may provide opportunities for individuals with disabilities to participate in necessary activities and meaningful occupations. This inquiry methodically collects and reports on research related to SRT for individuals with disabilities and impairments. MATERIALS AND METHODS: Using the Arksey and O'Malley framework and PRISMA guidelines, five databases were queried and indexes of 11 journals were hand-searched for relevant articles. Articles were included if they were published after 2005, involved SRT, written in English, and participants(s) had a disability. Articles were charted, categorised for level of evidence, and findings were summarised. RESULTS AND CONCLUSIONS: Of the 78 articles that were retrieved, 13 met inclusion criteria and were organised into 4 categories: SRT in primary and secondary education, in post-secondary education, for daily living, and without a specified context. No included articles considered SRT in vocational contexts. It was determined that SRT is a tool that may improve participation and independence of individuals with disabilities in multiple contexts. Most studies reviewed were non-empirical. Opportunities exist for providers to continue to develop a rigorous body of knowledge for the use of SRT to meet educational, vocational and daily living needs.IMPLICATIONS FOR REHABILITATIONSpeech recognition technology (SRT) provides a method of access that is widely available in mainstream technology devices such as personal computers, smartphones and mobile devices, and smart speakers/daily living aids.SRT may improve participation and independence of individuals with disabilities in contexts such as primary and secondary education, post-secondary education, and with independent living tasks.Many studies examining SRT are non-empirical, and there is an opportunity for assistive technology professionals and other providers who use assistive technology to continue to develop a rigorous body of knowledge.
Towards neuroscience of the everyday world (NEW) using functional near infrared spectroscopy
(Elsevier BV, 2021-02) von Lühmann, Alexander; Zheng, Yilei; Ortega-Martinez, Antonio; Kiran, Swathi; Somers, David C.; Cronin-Golomb, Alice; Awad, Louis N.; Ellis, Terry D.; Boas, David A.; Yücel, Meryem A.
Functional near-infrared spectroscopy (fNIRS) assesses human brain activity by noninvasively measuring changes of cerebral hemoglobin concentrations caused by modulation of neuronal activity. Recent progress in signal processing and advances in system design, such as miniaturization, wearability, and system sensitivity, have strengthened fNIRS as a viable and cost-effective complement to functional magnetic resonance imaging, expanding the repertoire of experimental studies that can be performed by the neuroscience community. The availability of fNIRS and electroencephalography for routine, increasingly unconstrained, and mobile brain imaging is leading toward a new domain that we term “Neuroscience of the Everyday World” (NEW). In this light, we review recent advances in hardware, study design, and signal processing, and discuss challenges and future directions.
Reliability of single-subject neural activation patterns in speech production tasks
(2021-01) Frankford, Saul A.; Nieto-Castañón, Alfonso; Tourville, Jason A.; Guenther, Frank H.
Speech neuroimaging research targeting individual speakers could help elucidate differences that may be crucial to understanding speech disorders. However, this research necessitates reliable brain activation across multiple speech production sessions. In the present study, we evaluated the reliability of speech-related brain activity measured by functional magnetic resonance imaging data from twenty neuro-typical subjects who participated in two experiments involving reading aloud simple speech stimuli. Using traditional methods like the Dice and intraclass correlation coefficients, we found that most individuals displayed moderate to high reliability. We also found that a novel machine-learning subject classifier could identify these individuals by their speech activation patterns with 97% accuracy from among a dataset of seventy-five subjects. These results suggest that single-subject speech research would yield valid results and that investigations into the reliability of speech activation in people with speech disorders are warranted.
Putative protective neural mechanisms in prereaders with a family history of dyslexia who subsequently develop typical reading skills
(2020-07) Yu, Xi; Zuk, Jennifer; Perdue, Meaghan V.; Ozernov-Palchik, Ola; Raney, Talia; Beach, Sarah D.; Norton, Elizabeth S.; Ou, Yangming; Gabrieli, John D.E.; Gaab, Nadine
Developmental dyslexia affects 40-60% of children with a familial risk (FHD+) compared to a general prevalence of 5-10%. Despite the increased risk, about half of FHD+ children develop typical reading abilities (FHD+Typical). Yet the underlying neural characteristics of favorable reading outcomes in at-risk children remain unknown. Utilizing a retrospective, longitudinal approach, this study examined whether putative protective neural mechanisms can be observed in FHD+Typical at the prereading stage. Functional and structural brain characteristics were examined in 47 FHD+ prereaders who subsequently developed typical (n = 35) or impaired (n = 12) reading abilities and 34 controls (FHD-Typical). Searchlight-based multivariate pattern analyses identified distinct activation patterns during phonological processing between FHD+Typical and FHD-Typical in right inferior frontal gyrus (RIFG) and left temporo-parietal cortex (LTPC) regions. Follow-up analyses on group-specific classification patterns demonstrated LTPC hypoactivation in FHD+Typical compared to FHD-Typical, suggesting this neural characteristic as an FHD+ phenotype. In contrast, RIFG showed hyperactivation in FHD+Typical than FHD-Typical, and its activation pattern was positively correlated with subsequent reading abilities in FHD+ but not controls (FHD-Typical). RIFG hyperactivation in FHD+Typical was further associated with increased interhemispheric functional and structural connectivity. These results suggest that some protective neural mechanisms are already established in FHD+Typical prereaders supporting their typical reading development.
Neural correlates of phonological processing: Disrupted in children with dyslexia and enhanced in musically trained children
(2018-11) Zuk, Jennifer; Perdue, Meaghan V.; Becker, Bryce; Yu, Xi; Chang, Michelle; Raschle, Nora Maria; Gaab, Nadine
Phonological processing has been postulated as a core area of deficit among children with dyslexia. Reduced brain activation during phonological processing in children with dyslexia has been observed in left-hemispheric temporoparietal regions. Musical training has shown positive associations with phonological processing abilities, but the neural mechanisms underlying this relationship remain unspecified. The present research aims to distinguish neural correlates of phonological processing in school-age typically developing musically trained children, musically untrained children, and musically untrained children with dyslexia utilizing fMRI. A whole-brain ANCOVA, accounting for gender and nonverbal cognitive abilities, identified a main effect of group in bilateral temporoparietal regions. Subsequent region-of-interest analyses replicated temporoparietal hypoactivation in children with dyslexia relative to typically developing children. By contrast, musically trained children showed greater bilateral activation in temporoparietal regions when compared to each musically untrained group. Therefore, musical training shows associations with enhanced bilateral activation of left-hemispheric regions known to be important for reading. Findings suggest that engagement of these regions through musical training may underlie the putative positive effects of music on reading development. This supports the hypothesis that musical training may facilitate the development of a bilateral compensatory neural network, which aids children with atypical function in left-hemispheric temporoparietal regions.
Investigating the neural correlates of voice versus speech-sound directed information in pre-school children.
(2014) Raschle, Nora Maria; Smith, Sara Ashley; Zuk, Jennifer; Dauvermann, Maria Regina; Figuccio, Michael Joseph; Gaab, Nadine
Studies in sleeping newborns and infants propose that the superior temporal sulcus is involved in speech processing soon after birth. Speech processing also implicitly requires the analysis of the human voice, which conveys both linguistic and extra-linguistic information. However, due to technical and practical challenges when neuroimaging young children, evidence of neural correlates of speech and/or voice processing in toddlers and young children remains scarce. In the current study, we used functional magnetic resonance imaging (fMRI) in 20 typically developing preschool children (average age = 5.8 y; range 5.2-6.8 y) to investigate brain activation during judgments about vocal identity versus the initial speech sound of spoken object words. FMRI results reveal common brain regions responsible for voice-specific and speech-sound specific processing of spoken object words including bilateral primary and secondary language areas of the brain. Contrasting voice-specific with speech-sound specific processing predominantly activates the anterior part of the right-hemispheric superior temporal sulcus. Furthermore, the right STS is functionally correlated with left-hemispheric temporal and right-hemispheric prefrontal regions. This finding underlines the importance of the right superior temporal sulcus as a temporal voice area and indicates that this brain region is specialized, and functions similarly to adults by the age of five. We thus extend previous knowledge of voice-specific regions and their functional connections to the young brain which may further our understanding of the neuronal mechanism of speech-specific processing in children with developmental disorders, such as autism or specific language impairments.
Behavioral and neural correlates of executive functioning in musicians and non-musicians
(2014) Zuk, Jennifer; Benjamin, Christopher; Kenyon, Arnold; Gaab, Nadine
Executive functions (EF) are cognitive capacities that allow for planned, controlled behavior and strongly correlate with academic abilities. Several extracurricular activities have been shown to improve EF, however, the relationship between musical training and EF remains unclear due to methodological limitations in previous studies. To explore this further, two experiments were performed; one with 30 adults with and without musical training and one with 27 musically trained and untrained children (matched for general cognitive abilities and socioeconomic variables) with a standardized EF battery. Furthermore, the neural correlates of EF skills in musically trained and untrained children were investigated using fMRI. Adult musicians compared to non-musicians showed enhanced performance on measures of cognitive flexibility, working memory, and verbal fluency. Musically trained children showed enhanced performance on measures of verbal fluency and processing speed, and significantly greater activation in pre-SMA/SMA and right VLPFC during rule representation and task-switching compared to musically untrained children. Overall, musicians show enhanced performance on several constructs of EF, and musically trained children further show heightened brain activation in traditional EF regions during task-switching. These results support the working hypothesis that musical training may promote the development and maintenance of certain EF skills, which could mediate the previously reported links between musical training and enhanced cognitive skills and academic achievement.
Musical, language, and reading abilities in early Portuguese readers
(2013) Zuk, Jennifer; Andrade, Paulo E.; Andrade, Olga V.C.A.; Gardiner, Martin; Gaab, Nadine
Early language and reading abilities have been shown to correlate with a variety of musical skills and elements of music perception in children. It has also been shown that reading impaired children can show difficulties with music perception. However, it is still unclear to what extent different aspects of music perception are associated with language and reading abilities. Here we investigated the relationship between cognitive-linguistic abilities and a music discrimination task that preserves an ecologically valid musical experience. 43 Portuguese-speaking students from an elementary school in Brazil participated in this study. Children completed a comprehensive cognitive-linguistic battery of assessments. The music task was presented live in the music classroom, and children were asked to code sequences of four sounds on the guitar. Results show a strong relationship between performance on the music task and a number of linguistic variables. A principle component analysis of the cognitive-linguistic battery revealed that the strongest component (Prin1) accounted for 33% of the variance and Prin1 was significantly related to the music task. Highest loadings on Prin1 were found for reading measures such as Reading Speed and Reading Accuracy. Interestingly, 22 children recorded responses for more than four sounds within a trial on the music task, which was classified as Superfluous Responses (SR). SR was negatively correlated with a variety of linguistic variables and showed a negative correlation with Prin1. When analyzing children with and without SR separately, only children with SR showed a significant correlation between Prin1 and the music task. Our results provide implications for the use of an ecologically valid music-based screening tool for the early identification of reading disabilities in a classroom setting.
Enhanced syllable discrimination thresholds in musicians
(2013) Zuk, Jennifer; Ozernov-Palchik, Ola; Kim, Heesoo; Lakshminarayanan, Kala; Gabrieli, John D.E.; Tallal, Paula; Gaab, Nadine
Speech processing inherently relies on the perception of specific, rapidly changing spectral and temporal acoustic features. Advanced acoustic perception is also integral to musical expertise, and accordingly several studies have demonstrated a significant relationship between musical training and superior processing of various aspects of speech. Speech and music appear to overlap in spectral and temporal features; however, it remains unclear which of these acoustic features, crucial for speech processing, are most closely associated with musical training. The present study examined the perceptual acuity of musicians to the acoustic components of speech necessary for intra-phonemic discrimination of synthetic syllables. We compared musicians and non-musicians on discrimination thresholds of three synthetic speech syllable continua that varied in their spectral and temporal discrimination demands, specifically voice onset time (VOT) and amplitude envelope cues in the temporal domain. Musicians demonstrated superior discrimination only for syllables that required resolution of temporal cues. Furthermore, performance on the temporal syllable continua positively correlated with the length and intensity of musical training. These findings support one potential mechanism by which musical training may selectively enhance speech perception, namely by reinforcing temporal acuity and/or perception of amplitude rise time, and implications for the translation of musical training to long-term linguistic abilities.
Relating pitch awareness to phonemic awareness in children: implications for tone-deafness and dyslexia
(2011) Loui, Psyche; Kroog, Kenneth; Zuk, Jennifer; Winner, Ellen; Schlaug, Gottfried
Language and music are complex cognitive and neural functions that rely on awareness of one's own sound productions. Information on the awareness of vocal pitch, and its relation to phonemic awareness which is crucial for learning to read, will be important for understanding the relationship between tone-deafness and developmental language disorders such as dyslexia. Here we show that phonemic awareness skills are positively correlated with pitch perception-production skills in children. Children between the ages of seven and nine were tested on pitch perception and production, phonemic awareness, and IQ. Results showed a significant positive correlation between pitch perception-production and phonemic awareness, suggesting that the relationship between musical and linguistic sound processing is intimately linked to awareness at the level of pitch and phonemes. Since tone-deafness is a pitch-related impairment and dyslexia is a deficit of phonemic awareness, we suggest that dyslexia and tone-deafness may have a shared and/or common neural basis.
Auditory-motor mapping training as an intervention to facilitate speech output in non-verbal children with autism: a proof of concept study.
(2011) Wan, Catherine Y.; Bazen, Loes; Baars, Rebecca; Libenson, Amanda; Zipse, Lauryn; Zuk, Jennifer; Norton, Andrea; Schlaug, Gottfried
Although up to 25% of children with autism are non-verbal, there are very few interventions that can reliably produce significant improvements in speech output. Recently, a novel intervention called Auditory-Motor Mapping Training (AMMT) has been developed, which aims to promote speech production directly by training the association between sounds and articulatory actions using intonation and bimanual motor activities. AMMT capitalizes on the inherent musical strengths of children with autism, and offers activities that they intrinsically enjoy. It also engages and potentially stimulates a network of brain regions that may be dysfunctional in autism. Here, we report an initial efficacy study to provide 'proof of concept' for AMMT. Six non-verbal children with autism participated. Prior to treatment, the children had no intelligible words. They each received 40 individual sessions of AMMT 5 times per week, over an 8-week period. Probe assessments were conducted periodically during baseline, therapy, and follow-up sessions. After therapy, all children showed significant improvements in their ability to articulate words and phrases, with generalization to items that were not practiced during therapy sessions. Because these children had no or minimal vocal output prior to treatment, the acquisition of speech sounds and word approximations through AMMT represents a critical step in expressive language development in children with autism.
Neural substrates of verbal repetition deficits in primary progressive aphasia.
(2021) Miller, Hillary E.; Cordella, Claire; Collins, Jessica A.; Ezzo, Rania; Quimby, Megan; Hochberg, Daisy; Tourville, Jason A.; Dickerson, Bradford C.; Guenther, Frank H.
In this cross-sectional study, we examined the relationship between cortical thickness and performance on several verbal repetition tasks in a cohort of patients with primary progressive aphasia in order to test predictions generated by theoretical accounts of phonological working memory that predict phonological content buffers in left posterior inferior frontal sulcus and supramarginal gyrus. Cortical surfaces were reconstructed from magnetic resonance imaging scans from 42 participants diagnosed with primary progressive aphasia. Cortical thickness was measured in a set of anatomical regions spanning the entire cerebral cortex. Correlation analyses were performed between cortical thickness and average score across three phonological working memory-related tasks: the Repetition sub-test from the Western Aphasia Battery, a forward digit span task, and a backward digit span task. Significant correlations were found between average working memory score across tasks and cortical thickness in left supramarginal gyrus and left posterior inferior frontal sulcus, in support of prior theoretical accounts of phonological working memory. Exploratory whole-brain correlation analyses performed for each of the three behavioural tasks individually revealed a distinct set of positively correlated regions for each task. Comparison of cortical thickness measures from different primary progressive aphasia sub-types to cortical thickness in age-matched controls further revealed unique patterns of atrophy in the different subtypes.
Dissociation between phonological working memory structures and motor programming units during speech motor sequence learning
(2020) Masapollo, Matthew; Guenther, Frank
Plug-and-play supervisory control using muscle and brain signals for real-time gesture and error detection
(Springer Science and Business Media LLC, 2020-09) DelPreto, Joseph; Salazar-Gomez, Andres F.; Gil, Stephanie; Hasani, Ramin; Guenther, Frank H.; Rus, Daniela
Effective human supervision of robots can be key for ensuring correct robot operation in a variety of potentially safety-critical scenarios. This paper takes a step towards fast and reliable human intervention in supervisory control tasks by combining two streams of human biosignals: muscle and brain activity acquired via EMG and EEG, respectively. It presents continuous classification of left and right hand-gestures using muscle signals, time-locked classification of error-related potentials using brain signals (unconsciously produced when observing an error), and a framework that combines these pipelines to detect and correct robot mistakes during multiple-choice tasks. The resulting hybrid system is evaluated in a “plug-and-play” fashion with 7 untrained subjects supervising an autonomous robot performing a target selection task. Offline analysis further explores the EMG classification performance, and investigates methods to select subsets of training data that may facilitate generalizable plug-and-play classifiers.
Behavioral and neural correlates of speech motor sequence learning in stuttering and neurotypical speakers: an fMRI investigation
(2021-02-01) Masapollo, Matthew; Segawa, Jen; Beal, Derek; Tourville, Jason; Nieto-Castanon, Alfonso; Guenther, Frank
Stuttering is a neurodevelopmental disorder characterized by impaired production of coordinated articulatory movements needed for fluent speech. It is currently unknown whether these abnormal production characteristics reflect disruptions to brain mechanisms underlying the acquisition and/or execution of speech motor sequences. To dissociate learning and control processes, we used a motor sequence learning paradigm to examine the behavioral and neural correlates of learning to produce novel phoneme sequences in adults who stutter (AWS) and neurotypical controls. Participants intensively practiced producing pseudowords containing non-native consonant clusters (e.g., “GVAZF”) over two days. The behavioral results indicated that although the two experimental groups showed comparable learning trajectories, AWS performed significantly worse on the task prior to and after speech motor practice. Using functional magnetic resonance imaging (fMRI), the authors compared brain activity during articulation of the practiced words and a set of novel pseudowords (matched in phonetic complexity). FMRI analyses revealed no differences between AWS and controls in cortical or subcortical regions; both groups showed comparable increases in activation in left-lateralized brain areas implicated in phonological working memory and speech motor planning during production of the novel sequences compared to the practiced sequences. Moreover, activation in left-lateralized basal ganglia sites was negatively correlated with in-scanner mean disfluency in AWS. Collectively, these findings demonstrate that AWS exhibit no deficit in constructing new speech motor sequences but do show impaired execution of these sequences before and after they have been acquired and consolidated.

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