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Palatalization refers to a type of coarticulation in which the place of articulation of some sound is closer to the palate than otherwise expected, very often triggered by adjacent palatal segments. It has been known as one of the most dynamic phonological phenomena in phonetic and phonological research, but the articulatory nature of palatalization still merits further investigation. This dissertation investigates the articulatory patterns of palatalization in Korean, English, and Scottish Gaelic (Gàidhlig), all of which are typologically distinct from one another and exhibit both language-universal and language-specific palatalization processes. The main question asked in this dissertation is which articulatory properties of palatalization are universal across languages, and specific to languages or to individuals. Three production experiments using ultrasound imaging technology were conducted to capture tongue gestures of speakers from three different language groups. The results from 30 speakers in the three language groups show that both phonemic and phonetic plain vs. palatalized differences manifest gesturally. Furthermore, the results show that there is a significant amount of articulatory variability across languages and speakers, yielding no clear universal "palatal" gesture, but some articulatory strategies seem to be shared by speakers from different languages. The theoretical and empirical implications of the findings are discussed.

Absence or impairment of functional communication is a fundamental deficit in Autism Spectrum Disorder (ASD). The specific factors that contribute to a great variety of speech and language impairments are still unknown but have a neurobiological substratum. We investigated the brain control of speech production mechanism in children with ASD using Magnetoencephalography (MEG). MEG is a neuroimaging modality with high temporal resolution that records neural activation in real time. A group of children with ASD and age- and sex- matched controls performed simple oromotor (open and close mouth) and speech tasks (one-syllable and multi-syllable phoneme production). Atypical and significantly different brain neural activation in motor (BA 6 and BA 4) areas and speech control (BA 47, BA 22) areas were noted in children with ASD compared to typically developing controls. The present thesis provides new evidence contributing to the understanding of speech and language production in individuals with autism.

Absence or impairment of functional communication is a fundamental deficit in Autism Spectrum Disorder (ASD). The specific factors that contribute to a great variety of speech and language impairments are still unknown but have a neurobiological substratum. We investigated the brain control of speech production mechanism in children with ASD using Magnetoencephalography (MEG). MEG is a neuroimaging modality with high temporal resolution that records neural activation in real time. A group of children with ASD and age- and sex- matched controls performed simple oromotor (open and close mouth) and speech tasks (one-syllable and multi-syllable phoneme production). Atypical and significantly different brain neural activation in motor (BA 6 and BA 4) areas and speech control (BA 47, BA 22) areas were noted in children with ASD compared to typically developing controls. The present thesis provides new evidence contributing to the understanding of speech and language production in individuals with autism.

Models of speech production postulate that, in order to facilitate rapid and precise control of articulation, the predicted auditory feedback is sent to the auditory system to be compared with incoming sensory data. If this is so, an 'error' signal may be observed when the predicted auditory feedback and the sensory consequences of vocalization do not match. I used event-related fMRI to look for the neural concomitants of such an error signal. In two conditions volunteers whispered 'ted'. In one of these, voice-gated noise implemented in our real-time processing system was used to mask the auditory feedback, which should result in an error signal. Two other conditions were yoked to the production conditions (either clearly heard or masked), but were listen-only and therefore no error signal would be expected. I acquired whole-brain EPI data from 21 subjects using a fast-sparse design. Activity in the superior temporal gyrus bilaterally was significantly greater for clear than masked speech during the listen-only trials (F(1,20)≥12.84, p<0.002), and significantly higher for masked than for clear speech in the production trials (F(1,20)≥6.68, p<0.02). This crossover interaction indicates that speech production results in corollary discharge in the auditory system and furthermore suggests that this corollary discharge reflects expectations about the sensory concomitants of speech acts. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2007-09-26 10:02:35.972

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No description available.

No description available.

Apraxia of speech (AOS) is a motor speech disorder that poses significant obstacles to a person's ability to communicate and take part in everyday life. Agreement exists between current theories of AOS that the impairment affects the speech motor planning stage, where linguistic representations are transformed into speech movements, but they disagree on the specific nature of the breakdown at this processing level. A more detailed understanding of this impairment is essential for developing targeted, effective treatment approaches and for identifying the appropriate candidates for these treatments. The study of AOS is complicated by the fact that this disorder rarely occurs in isolation but is commonly accompanied by various degrees of aphasia (a language impairment) and/or dysarthria (a neuromuscular impairment of speech motor control). In addition, the behavioral similarities of AOS and its closest clinical neighbor, aphasia with phonemic paraphasias, undermine the usefulness of traditional methods, such as perceptual error analysis, in the study of both disorders. The purpose of this dissertation was to test three competing hypotheses about the specific nature of the speech motor planning impairment in AOS in a systematic sequence of three reaction time experiments. This research was formulated in the context of a well-established theoretical framework of speech production and it combines psycholinguistic reaction time paradigms with a cognitive neuropsychological approach. The results of the three experiments provide evidence that one component of the speech motor planning impairment in AOS involves difficulty with selecting the intended motor program for articulation. Furthermore, this difficulty appears to be intensified by simultaneously activated alternative speech motor programs that compete with the target program for selection. These findings may prove useful as a theoretically-motivated basis for improving diagnostic tools and treatment protocols for people with AOS and aphasia, thus enhancing clinical decision-making. Such translational and clinical research aimed at developing sensitive and specific diagnostic tools and improving treatment approaches is the ultimate long-term objective of this research program.

Studies in adults showed differential neural processing between overt and inner speech. So far, it is unclear whether inner and overt speech are processed differentially in children. The present study examines the pre-activation of the speech network in order to disentangle domain-general executive control from linguistic control of inner and overt speech production in 6- to 7-year-olds by simultaneously applying electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS). Children underwent a picture-naming task in which the pure preparation of a subsequent speech production and the actual execution of speech can be differentiated. The preparation phase does not represent speech per se but it resembles the setting up of the language production network. Only the fNIRS revealed a larger activation for overt, compared to inner, speech over bilateral prefrontal to parietal regions during the preparation phase. Findings suggest that the children’s brain can prepare the subsequent speech production. The preparation for overt and inner speech requires different domain-general executive control. In contrast to adults, the children’s brain did not show differences between inner and overt speech when a concrete linguistic content occurs and a concrete execution is required. This might indicate that domain-specific executive control processes are still under development.