Foster K D, Woda A, Peyron M A
Déficience, Incapacité et Désavantage en Sauté Ozole, Dental Faculty, University of Auvergne, Clermont-Ferrand, France.
J Neurophysiol. 2006 Jun;95(6):3469-79. doi: 10.1152/jn.01003.2005.
Mastication is continually modified throughout the chewing sequence in response to the texture of the food. The aim of this work was to compare the effects of an increase in hardness of two model food types, presenting either elastic or plastic rheological properties, on mastication. Each model food type consisted of four products of different hardness. Sensory testing experiments conducted with one group of 14 subjects showed significant perceived differences between products in terms of their increasing hardness. Fifteen other volunteers were asked to chew three replicates of each elastic and plastic product during two sessions. EMGs of masseter and temporalis muscles were recorded simultaneously with jaw movement during chewing. Numerous variables were analyzed from these masticatory recordings. Multiple linear regression analyses were used to assess the respective effects of food hardness and rheological properties on variables characterizing either the whole masticatory sequence or different stages of the sequence. Muscle activities were significantly affected by an increase in hardness regardless of the food type, whereas the shape of the cycles depended on the rheological properties. The masticatory frequency was affected by hardness at the initial stage of the sequence but overall frequency adaptation was better explained by a change in rheological behavior, with plastic products being chewed at a slower frequency. A dual hypothesis was proposed, implicating first a cortical-brain stem preprogrammed mechanism to adapt the shape of the jaw movements to the rheological properties of the food, and second, a brain stem mechanism with mainly sensory feedback from the mouth to adapt muscle force to the food hardness.
在咀嚼过程中，咀嚼行为会根据食物质地不断调整。本研究旨在比较两种具有弹性或塑性流变特性的模型食物硬度增加对咀嚼的影响。每种模型食物类型由四种不同硬度的产品组成。对一组14名受试者进行的感官测试实验表明，不同产品在硬度增加方面存在显著的感知差异。另外15名志愿者被要求在两个阶段中咀嚼每种弹性和塑性产品各三次。在咀嚼过程中，同时记录咬肌和颞肌的肌电图以及下颌运动。从这些咀嚼记录中分析了许多变量。使用多元线性回归分析来评估食物硬度和流变特性对表征整个咀嚼过程或该过程不同阶段的变量的各自影响。无论食物类型如何，硬度增加都会显著影响肌肉活动，而咀嚼周期的形状则取决于流变特性。咀嚼频率在咀嚼序列的初始阶段受硬度影响，但总体频率适应性更好地由流变行为的变化来解释，塑性产品的咀嚼频率较慢。提出了一个双重假设，首先涉及一种皮质 - 脑干预编程机制，使下颌运动的形状适应食物的流变特性，其次涉及一种脑干机制，主要通过来自口腔的感觉反馈使肌肉力量适应食物硬度。
