Logopenic and nonfluent variants of primary progressive aphasia are differentiated by acoustic measures of speech production

Differentiation of logopenic (lvPPA) and nonfluent/agrammatic (nfvPPA) variants of Primary Progressive Aphasia is important yet remains challenging since it hinges on expert based evaluation of speech and language production. In this study acoustic measures of speech in conjunction with voxel-based morphometry were used to determine the success of the measures as an adjunct to diagnosis and to explore the neural basis of apraxia of speech in nfvPPA. Forty-one patients (21 lvPPA, 20 nfvPPA) were recruited from a consecutive sample with suspected frontotemporal dementia. Patients were diagnosed using the current gold-standard of expert perceptual judgment, based on presence/absence of particular speech features during speaking tasks. Seventeen healthy age-matched adults served as controls. MRI scans were available for 11 control and 37 PPA cases; 23 of the PPA cases underwent amyloid ligand PET imaging. Measures, corresponding to perceptual features of apraxia of speech, were periods of silence during reading and relative vowel duration and intensity in polysyllable word repetition. Discriminant function analyses revealed that a measure of relative vowel duration differentiated nfvPPA cases from both control and lvPPA cases (r2 = 0.47) with 88% agreement with expert judgment of presence of apraxia of speech in nfvPPA cases. VBM analysis showed that relative vowel duration covaried with grey matter intensity in areas critical for speech motor planning and programming: precentral gyrus, supplementary motor area and inferior frontal gyrus bilaterally, only affected in the nfvPPA group. This bilateral involvement of frontal speech networks in nfvPPA potentially affects access to compensatory mechanisms involving right hemisphere homologues. Measures of silences during reading also discriminated the PPA and control groups, but did not increase predictive accuracy. Findings suggest that a measure of relative vowel duration from of a polysyllable word repetition task may be sufficient for detecting most cases of apraxia of speech and distinguishing between nfvPPA and lvPPA

Phonological and Speech Motor Abilities in Children with Childhood Apraxia of Speech and Phonological Disorder

This thesis investigated whether childhood apraxia of speech (CAS) differs from phonological disorder (PD) regarding their causal origin. After developing and validating measures targeting components of phonology and speech motor control, we explored if speech motor ability constrained phonological development in CAS more than in PD. This thesis demonstrated children with CAS show a distinct profile of speech impairments but little evidence that their motor deficit constrains phonological development in a way distinct from PD

The articulatory basis of positional asymmetries in phonological acquisition

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Linguistics and Philosophy, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 250-276).Child phonological processes that lack counterparts in adult phonological typology have long posed a problem for formal modeling of phonological acquisition. This dissertation investigates child-specific processes with a focus on the phenomenon of neutralization in strong position, whereby children preferentially neutralize phonemic contrast in precisely those contexts seen to support maximal contrast in adult systems. These processes are difficult to model without making incorrect predictions for adult typology. Here, it is argued that all genuinely child-specific processes are driven by constraints rooted in child-specific phonetic factors. In a phonetically-based approach to phonology, if there are areas of divergence in phonetic pressures across immature and mature systems, differences across child and adult phonologies are predicted rather than problematic. The phonetically-based approach also explains the developmental elimination of child-specific processes, since in the course of typical maturation, the phonetic pressures driving these effects will cease to apply. Because children's speech-motor control capabilities are known to diverge from those of the skilled adult speaker, it is posited that articulatory factors play the dominant role in shaping child-specific phonological processes. Here it is argued that children have difficulty executing discrete movements of individual articulators, notably the tongue. By moving the tongue-jaw complex as a single unit, the child speaker can reduce the number of degrees of movement freedom and also rely on the action of the motorically simpler mandible to achieve articulatory targets.(cont.) The effects of mandibular dominance have previously been argued to play a role in shaping sound patterns in babbling and early words (MacNeilage & Davis, 1990). The preference for jaw-dominated movement can be seen to recede over time as the child establishes more reliable articulatory control. However, here evidence from the productions of older children is presented indicating that these effects continue to have an influence in later stages of development than has been previously documented. The pressure to use simultaneous movements of the tongue-jaw complex, formalized in a constraint MOVE-AS-UNIT, is argued to play a role in shaping child-specific processes including positional velar fronting, prevocalic fricative gliding, and consonant harmony. In the present approach, children's tendency to neutralize contrast in strong positions arises as MOVE-AS-UNIT interacts with asymmetries in the force and duration of articulatory gestures across different prosodic contexts. The incorporation of child-specific phonetic factors makes it possible to account for complex patterns of conditioning in child speech processes that would under other assumptions be extremely challenging to model.by Tara K. McAllister.Ph.D

Exploring the use of Technology for Assessment and Intensive Treatment of Childhood Apraxia of Speech

Given the rapid advances in technology over the past decade, this thesis examines the potential for automatic speech recognition (ASR) technology to expedite the process of objective analysis of speech, particularly for lexical stress patterns in childhood apraxia of speech. This dissertation also investigates the potential for mobile technology to bridge the gap between current service delivery models in Australia and best practice treatment intensity for CAS. To address these two broad aims, this thesis describes three main projects. The first is a systematic literature review summarising the development, implementation and accuracy of automatic speech analysis tools when applied to evaluation and modification of children’s speech production skills. Guided by the results of the systematic review, the second project presents data on the accuracy and clinical utility of a custom-designed lexical stress classification tool, designed as part of a multi-component speech analysis system for a mobile therapy application, Tabby Talks, for use with children with CAS. The third project is a randomised control trial exploring the effect of different types of feedback on response to intervention for children with CAS. The intervention was designed to specifically explore the feasibility and effectiveness of using an app equipped with ASR technology to provide feedback on speech production accuracy during home practice sessions, simulating the common service delivery model in Australia. The thesis concludes with a discussion of future directions for technology-based speech assessment and intensive speech production practice, guidelines for future development of therapy tools that include more game-based practice activities and the contexts in which children can be transferred from predominantly clinician-delivered augmented feedback to ASR-delivered right/wrong feedback and continue to make optimal gains in acquisition and retention of speech production targets

Expressive language development in minimally verbal autistic children: exploring the role of speech production

Trajectories of expressive language development are highly heterogeneous in autism. I examine the hypothesis that co-morbid speech production difficulties may be a contributing factor for some minimally verbal autistic individuals. Chapters 1 and 2 provide an overview of language variation within autism, and existing intervention approaches for minimally verbal autistic children. These chapters situate this thesis within the existing literature. Chapter 3 describes a longitudinal study of expressive language in minimally verbal 3-5 year olds (n=27), with four assessment points over 12 months. Contrary to expectations, initial communicative intent, parent responsiveness and response to joint attention did not predict expressive language growth or outcome. Speech skills were significant predictors. Chapter 4 describes the design, development and feasibility testing of the BabbleBooster app, a novel, parent-meditated speech skills intervention, in which 19 families participated for 16 weeks. Acceptability feedback was positive but adherence was variable. I discuss how this could be improved in future iterations of the app and intervention protocol. Chapter 5 details how BabbleBooster’s efficacy was evaluated. For interventions with complex or rare populations, a randomized case series design is a useful alternative to an under-powered group trial. There was no evidence that BabbleBooster improved speech production scores, likely due to limited dosage. Future research using this study design could determine optimal treatment intensity and duration with an improved version of the app. Taken together, these studies underscore the contribution of speech production abilities to expressive language development in minimally verbal autistic individuals. I argue that this reflects an additional condition, and is not a consequence of core autism features. The intervention piloted here represents a first step towards developing a scalable tool for parents to support speech development in minimally verbal children, and illustrates the utility of randomized single case series for testing treatment effects in small, heterogeneous cohorts

The role of imitation in learning to pronounce.

Timing patterns and the qualities of speech sounds are two important aspects of pronunciation. It is generally believed that imitation from adult models is the mechanism by which a child replicates them. However, this account is unsatisfactory, both for theoretical reasons and because it leaves the developmental data difficult to explain. I describe two alternative mechanisms. The first explains some timing patterns (vowel length changes, 'rhythm', etc.) as emerging because a child's production apparatus is small, immature and still being trained. As a result, both the aerodynamics of his speech and his style of speech breathing differ markedly from the adult model. Under their constraints the child modifies his segmental output in various ways which have effects on speech timing but these effects are epiphenomenal rather than the result of being modelled directly. The second mechanism accounts for how children learn to pronounce speech sounds. The common, but actually problematic, assumption is that a child does this by judging the similarity between his own and others' output, and adjusting his production accordingly. Instead, I propose a role for the typical vocal interaction of early childhood where a mother reformulates ('imitates') her child's output, reflecting back the linguistic intentions she imputes to him. From this expert, adult judgment of either similarity or functional equivalence, the child can determine correspondences between his production and adult output. This learning process is more complex than simple imitation but generates the most natural of forms for the underlying representation of speech sounds. As a result, some longstanding problems in speech can be resolved and an integrated developmental account of production and perception emerges. Pronunciation is generally taught on the basis that imitation is the natural mechanism for its acquisition. If this is incorrect, then alternative methods should give better results than achieved at present

Social and Affective Neuroscience of Everyday Human Interaction

This Open Access book presents the current state of the art knowledge on social and affective neuroscience based on empirical findings. This volume is divided into several sections first guiding the reader through important theoretical topics within affective neuroscience, social neuroscience and moral emotions, and clinical neuroscience. Each chapter addresses everyday social interactions and various aspects of social interactions from a different angle taking the reader on a diverse journey. The last section of the book is of methodological nature. Basic information is presented for the reader to learn about common methodologies used in neuroscience alongside advanced input to deepen the understanding and usability of these methods in social and affective neuroscience for more experienced readers

Social and Affective Neuroscience of Everyday Human Interaction

This Open Access book presents the current state of the art knowledge on social and affective neuroscience based on empirical findings. This volume is divided into several sections first guiding the reader through important theoretical topics within affective neuroscience, social neuroscience and moral emotions, and clinical neuroscience. Each chapter addresses everyday social interactions and various aspects of social interactions from a different angle taking the reader on a diverse journey. The last section of the book is of methodological nature. Basic information is presented for the reader to learn about common methodologies used in neuroscience alongside advanced input to deepen the understanding and usability of these methods in social and affective neuroscience for more experienced readers