Effects of increased hardness on jaw movement and muscle activity during chewing of visco-elastic model foods

• Published in: Experimental brain research Vol. 142; no. 1; pp. 41 - 51
• Main Authors: PEYRON, M. A, LASSAUZAY, C, WODA, A
• Format: Journal Article
• Language: English
• Published: Berlin Springer 2002; Springer Nature B.V; Springer Verlag
• Subjects: Adult; Biological and medical sciences; Bite Force; Elasticity; Electromyography; Feedback - physiology; Female; Fundamental and applied biological sciences. Psychology; Human health and pathology; Humans; Jaw - innervation; Jaw - physiology; Life Sciences; Male; Masseter Muscle - innervation; Masseter Muscle - physiology; Mastication; Mastication - physiology; Masticatory Muscles - innervation; Masticatory Muscles - physiology; Models, Biological; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Muscle Contraction - physiology; Physical Exertion - physiology; Proprioception - physiology; Stress, Mechanical; Temporal Muscle - innervation; Temporal Muscle - physiology; Vertebrates: nervous system and sense organs; Human; Viscoelasticity; Jaw; Temporal muscle; Masseter muscle; Electrophysiology; Electromyography; Chewing; Motor control; Physical properties; Food; Motor program; food texture; mastication; electromyography; jaw movements; model food
• ISSN: 0014-4819; 1432-1106
• DOI: 10.1007/s00221-001-0916-5

When food is chewed, sensory feedback adapts the motor program to the characteristics of the food. However, the relationship between the physical properties of different foods and the motor response is poorly understood. In this study, we developed edible and well-controlled model foods in order to describe some of the stimulus-response functions of the food-mastication loop. Four gelatine-based visco-elastic model foods identical in shape and size but differing in hardness were prepared. They displayed reproducible sensory and physical characteristics and were distributed on a wide hardness scale. Electromyographic activity of masseter and temporalis muscles and jaw movements in the frontal plane were simultaneously recorded during mastication in 15 young men with intact dentition and good oral status. Almost all EMG and jaw movement parameters were clearly affected by increasing hardness of model foods. However, it is possible to summarise the results by reducing the number of parameters to three: the number of chewing cycles, EMG activity of any one of the two temporal or the two masseter muscles and the amplitude of the opening mandibular movements. Indeed, these were the best transcriptors of the hardness range of the model foods used in this study. As inferred from these parameter recordings, the food hardness modifications were strongest during the first five strokes, began as early as the first stroke and lasted for the whole sequence.