The Process Model of Feeding provides an understanding of the inter-related processes of mastication, oral food transport, and swallowing. Central to this model is the notion that foods are processed in the oral cavity but the swallow bolus formed in the pharynx. Movement of food in and through the oral cavity depends primarily on coordinated motions of the jaw, hyoid, and tongue. Although the basic motions have been described, the muscle activity patterns producing these motions have not. We propose to study of the kinesiology of feeding in normal adults. Motions will be recorded with videofluorography and muscle activity with electromyography. Some experiments will also include respiratory measures (expansion of the thoracoabdominal cavity and nasal air pressure). We will test the following hypotheses: 1. Cyclical movements of the hyoid bone in the sagittal plane are produced by the interaction of 3 muscle groups (jaw adductors, suprahyoid muscles, and infrahyoid muscles). 2. Although cyclical movements of the tongue surface result primarily from activity of its intrinsic muscles, they are also influenced by linkage to the jaw and hyoid bone, as well as extrinsic muscle contraction. 3. Mediolateral tongue surface motion is linked to jaw motion during food processing, and is assisted by differential activity of the jaw adductor muscles on each side. 4. The soft palate exhibits cyclical movement during eating and swallowing that is temporally linked to jaw motion. 5. Motion patterns of the jaw, hyoid, and tongue surface and the muscle activity patterns that produce them are cyclical and semi-rhythmic during eating; the sequential pattern of muscle activation is maintained across behaviors, though the duration and amplitude of contraction may vary. Data will be analyzed visually and by statistical analysis techniques including least-squares regression and time-series analysis. The results will further delineate the mechanisms of eating and swallowing, will have relevance to the evaluation and treatment of dysphagic individuals, and will enhance our knowledge of CNS control of mastication and swallowing, and their relationship to respiration. ? ?
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