Meeting Abstract
S2.10 Tuesday, Jan. 4 Determinants of variance in 3-D jaw kinematics in two species of primates IRIARTE-DIAZ, J.*; REED, D.A.; ROSS, C.F.; University of Chicago; University of Chicago; University of Chicago jiriarte@uchicago.edu
The mammalian feeding system presents practical advantages for the study of kinematics and its relationship to musculoskeletal morphology and neural and muscle activity. Because the animals can be conditioned to feed in a relatively constrained space, large amounts of high resolution kinematic and physiological data can be collected while the animals perform relatively normal behavioral sequences without concerns related to the elimination of natural variation. This ability to collect large numbers of jaw movement cycles makes it possible to study sources of variation in kinematics at a wide range of levels. Although most studies of mammalian feeding kinematics focus on the vertical motion of the mandible, the motion of the jaw is highly three-dimensional, particularly associated with tongue movement and the repositioning of the bolus in the oral cavity. Here we present data on the nature and sources of variation in three-dimensional jaw kinematics during feeding in two species of primates, Cebus sp. and Macaca mulatta, focusing on the effect of species, individuals, experimental sessions, food material properties, within sequence variation in cycle type, and within chew cycle variation in the gape cycle phases by using a repeated measures, nested multifactor model. As predicted from analyses of EMG data, the largest amount of variation in kinematics was found among chewing cycles, most likely the result of changes in food properties throughout the chewing sequence. When controlling by chew cycle, however, significant variation was found among species, individuals, and most significantly among sequences of different food type/material properties. We propose that by identifying the sources of variation of the kinematics of feeding we can use these data to test hypothesis regarding the evolution of motor patterns of mammalian feeding.
