DEVELOPMENT OF EARLY OROFACIAL MOTILITY AND CONTROL

University Of Wisconsin Madison, Madison WI

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Abstract

DESCRIPTION (adapted from applicant's abstract): The goal of this project is to identify the characteristics of the immature oromotor control system that shape early speech production. Fundamental similarities in vocal development within and across cultures suggest that young children have a propensity for certain articulatory movements and configurations (Kent, 1992; Locke, 1983; Oller, Eilers, Urbano, and Cobo-Lewis, 1997). These universal tendencies probably reflect the properties of the immature oromotor control system that, in part, delimit early phonetic abilities. The few existing studies of early articulatory control have revealed the coordinative organization for speech to emerge much earlier than previously suggested (Moore and Ruark, 1996; Ruark and Moore, 1997). Accordingly, an improved understanding of speech development requires more direct information about the organization of spontaneous and task-related orofacial movements produced in early infancy. Early lip and jaw movements and associated muscle activity will be studied in five different groups at differing stages of early development (age range: birth to 12 months) using a 3D computerized movement capture system. Movement data will be collected from the upper lip, lower lip, and jaw using three reflective markers placed midline on the vermilion border of the upper and lower lip, and just superior to the mental protuberance of the mandible. Muscle activity will be recorded using miniature surface electrodes from five targeted muscles sites: right temporalis, right masseter, anterior belly of digastric, right quadrant of the orbicularis oris superior, and right quadrant of the orbicularis oris inferior. Lip and jaw data will be subjected to analyses that will characterize early oromotor coordination and control at multiple levels (e.g., spatio-temporal stability, inter- articulator coupling, and frequency of movement). These analyses will also include the novel use of 3D movement space mapping to describe the diversity and richness of early lip and jaw movements exhibited at each age across and within distinct oromotor behaviors (e.g., spontaneous vs. chewing vs. sucking vs. vocalization). It is hypothesized that even newborn subjects will exhibit some stereotypic lip and jaw movement patterns for certain tasks and that changes in spontaneous movements will parallel changes in task-related movement patterns. The developmental sequence observed in this study will provide empirically based guidelines for advancing underlying movement competencies in children with speech motor delays and will lead to a descriptive framework in which speech motor delays can be detected at an earlier stage of development.