Christopher A. Moore, Ph.D. - US grants

A critical feature in the development of speech production models has been the capacity of the system to compensate rapidly for perturbations in the dynamic state of the orofacial structures. This ability has led some investigators to propose that speech motor control, like many other motor behaviors, is generative, continuously adapting to system dynamics within the limits of physiologically determined constraints. Pathological speech production due to sensorimotor deficit (i.e. dysarthria) might be modeled as the result of a change in those constraints, and therapeutic intervention might consequently be designed within that altered set. The specific objectives of the present investigation are to determine whether or not any changes in the motor organization of jaw movement occur in dysarthric speakers, and to evaluate the effects of therapeutic treatment in terms of promoting coordinative reorganization. In a larger sense this investigation is intended to determine whether or not the speech motor control system is capable of reorganization in response to alterations in the sensorimotor machinery. Furthermore, the ability of a speaker to change coordinative organization on the basis of therapeutic feedback will be assessed. These objectives will be addressed by quantifying jaw muscle coordination in speakers with Parkinsons's disease before and after a course of treatment for dysarthria. Jaw muscle activity will be recorded electromyographically and subjected to cross-correlational analysis to quantify patterns of activity among the jaw muscles. Mandibular kinematics and acoustic output will also be recorded and analyzed for changes following therapeutic treatment.

The physiological development of speech production has remained largely unexplored in spite of Us importance to understanding developmental speech disorders and to models of normal speech motor control. In theoretical models and clinical applications, speech coordination, like other complex motor behaviors, has been assumed to be derived from rhythmic, homeostatic, centrally patterned functions such as respiration, chewing, and sucking. This assumption has not been tested, and despite its intuitive appeal, might be doubted because of demonstrated differences between centrally patterned behaviors and speech production in adults (Moore, Smith, & Ringel, 1988). An empirical evaluation of this assumption has implications both for models of normal speech motor control and for the rationale underlying diagnosis and treatment of children with developmental speech disorders. The proposed Investigation of normally developing children contrasts the coordination of centrally patterned oral and respiratory behaviors with speech coordination. This contrast will provide a quantitative description of speech development in the context of well-understood motor behaviors. Physiological development of speech motor control in primary speech subsystems in young children (9-48 months of age) will be described using a cross-sectional (70 children) and longitudinal (20 children) design. Coordination of systems for respiratory drive, mandibular movement, phonation, and articulation will be quantified during speech and during automatic, rhythmic, non-speech behaviors such as chewing and resting breathing. Electromyographic (EMG), acoustic, and kinematic signals will be analyzed. Articulatory coordination and laryngeal control will be inferred from formant (F1 and F2) trajectories and fundamental frequency (f-o) contours. Relative timing of muscle activity will be quantified using correlational analysis of E G signals. Signal coherence arising from paired speech muscles will be computed in order to detect activity arising from a common neural source. Non-zero coherence within paired EMG signals has been shown to be an observable characteristic of rhythmic motor behaviors, including mastication and respiration, both of which are mediated by central pattern generators (CPGs) in many species. Developmental changes in the temporal and spectral characteristics of EMG signals will delineate the role of automatic, non-speech coordinative organization in speech maturation.

DESCRIPTION (from applicant's abstract): Advanced training in the speech, language, and hearing sciences is at a critical point in its short history. Although the national need for services and the demand for graduate training are steadily increasing, doctoral training in speech, language, and hearing sciences has been insufficient in keeping up with these needs. Projected faculty retirement and departmental growth outstrip production of doctoral graduates by approximately 50%. Doctoral training in the speech, language, and hearing sciences at the University of Washington has played a significant role in addressing this growing need. University of Washington graduates consistently compete for the best faculty and research positions in the country. Training experiences afforded by the UW training mentors include active research programs in: clinical audiology, hearing aid design and evaluation, neonatal hearing screening, psycholinguistics, phonology, auditory electrophysiology, multicultural aspects of communication, psychoacoustics, bioacoustics, social communication, speech perception, speech physiology, speech acoustics, motor speech disorders, neurogenic speech-language disorders, inner hair cell regeneration, oromotor coorination and biomechanics, song development in songbirds, cochlear implants, neuroimaging, and cognitive neuroscience. Program trainees are exposed to a wide range of research in speech, language, and hearing, emerging well versed in these disciplines and able to conduct technologically and theoretically ambitious programs of research. Independent projections and observations yield the common conclusions that: (1) The need for health care professionals in speech, language, and hearing sciences will rise steeply over the next several decades. Research efforts will need to rise commensurately. (2) The supply of new professionals remains limited by the number of graduate programs. Existing programs must maintain or increase their training efforts. (3) Growth in training programs is limited by a lack of qualified professor-ial research faculty. (4) Research institutions represent a compara-tively small proportion of training programs. This proposed research- training program addresses these needs by providing a highly enriched educational environment for predoctoral students. These students will be exposed to a broad range of interdisciplinary research as well as being mentored to develop as independent investigators within their more narrowly defined scope of research in preparation for academic careers encompassing both research and teaching.

The physiological development of speech production has remained largely unexplored in spite of Us importance to understanding developmental speech disorders and to models of normal speech motor control. In theoretical models and clinical applications, speech coordination, like other complex motor behaviors, has been assumed to be derived from rhythmic, homeostatic, centrally patterned functions such as respiration, chewing, and sucking. This assumption has not been tested, and despite its intuitive appeal, might be doubted because of demonstrated differences between centrally patterned behaviors and speech production in adults (Moore, Smith, & Ringel, 1988). An empirical evaluation of this assumption has implications both for models of normal speech motor control and for the rationale underlying diagnosis and treatment of children with developmental speech disorders. The proposed Investigation of normally developing children contrasts the coordination of centrally patterned oral and respiratory behaviors with speech coordination. This contrast will provide a quantitative description of speech development in the context of well-understood motor behaviors. Physiological development of speech motor control in primary speech subsystems in young children (9-48 months of age) will be described using a cross-sectional (70 children) and longitudinal (20 children) design. Coordination of systems for respiratory drive, mandibular movement, phonation, and articulation will be quantified during speech and during automatic, rhythmic, non-speech behaviors such as chewing and resting breathing. Electromyographic (EMG), acoustic, and kinematic signals will be analyzed. Articulatory coordination and laryngeal control will be inferred from formant (F1 and F2) trajectories and fundamental frequency (f-o) contours. Relative timing of muscle activity will be quantified using correlational analysis of E G signals. Signal coherence arising from paired speech muscles will be computed in order to detect activity arising from a common neural source. Non-zero coherence within paired EMG signals has been shown to be an observable characteristic of rhythmic motor behaviors, including mastication and respiration, both of which are mediated by central pattern generators (CPGs) in many species. Developmental changes in the temporal and spectral characteristics of EMG signals will delineate the role of automatic, non-speech coordinative organization in speech maturation.

? DESCRIPTION (provided by applicant): The objectives of the proposed Training Program are to provide advanced research training in the subdisciplines of Communication Sciences and Disorders to ten predoctoral and ten postdoctoral fellows (i.e., two new predoctoral and postdoctoral trainees will begin the program each year with the expectation that each will be supported for two years). This program is also intended to address the critical shortage of academic researchers in speech, language and hearing research, by drawing trainees from a very broad range of academic disciplines (i.e., including Biomedical Engineering, Neuroscience, and Speech, Language, and Hearing). During the training period, trainees will complete a range of required courses, participate in a weekly research symposium, and will complete a lab rotation that complements their research focus area. These activities have been selected to broaden the trainees' understanding of the full continuum of health research (i.e., from basic research through implementation of clinical practice). Trainees will integrate broadly into the community of researchers at Boston University in Communication Sciences and Disorders, and will also participate actively in national scientific conferences. The Training Faculty supporting this Training Program includes a very broad range of NIH-supported academic researchers focused on speech, language and hearing research. Key outcomes include the full range of accomplishments anticipated for high-achieving pre- and postdoctoral scholars: contributions to peer-reviewed manuscripts, application for federal research (e.g., NIH NRSA mechanisms) and/or training support, active participation in national or international scientific conferences, and eventually, employment by research universities with high levels of research activity.