Meeting Abstract

P1.123  Saturday, Jan. 4 15:30  Muscle Coordination during Mastication in Primates RAM, YV*; IRIARTE-DIAZ, J; ROSS, CF; Univ. of Chicago; Univ. of Chicago; Univ. of Chicago yashesvini@uchicago.edu

Previous studies indicate that trigeminal muscles can be divided into triplets that fire in synchrony and may be controlled by a small number of neural factors. In this study, EMG and kinematic data were used to analyze the coordination between the left and right trigeminal muscles (Anterior/Posterior Temporalis, Superficial/Deep Masseter, Medial Pterygoid, Digastric) during mastication in primates. Coordination in amplitude of recruitment and timing of activation were quantified as evidence that two muscles are controlled by a single neural factor. We predicted that muscles that are recruited together (i.e., triplets) would be more tightly coordinated with each other than with other muscles. In the frequency domain, the EMG signal was decomposed into sinusoids of various frequencies to create the power spectrum. The phase spectrum describes the phase shifts that must be applied to each sinusoid to obtain the original EMG signal. Coherence of power and phase in the frequency domain was used to quantify the coordination between muscles. Our results show that triplets of muscles that fire together are not more tightly coordinated with each other than with other muscles. These results indicate that muscles that fire synchronously (triplets) are not necessarily controlled by a single neural factor and their coordination may be a byproduct of other neural influences.