Wavelet analysis of masseter muscle EMG during emotional provocation

It is believed that emotion plays an important part in jaw muscle mediation. Temporomandibular disorders (TMD) are thought to have an origin in stress induced muscle fiber damage. This article details the results of a wavelet analysis performed on electro-myography (EMG) signals recorded from the cat masseter (jaw) muscle during hypothalamic stimulation. This stimulation induces the rage response and serves as the emotional provocation condition. These data were then compared to EMG recordings taken from the masseter muscle during mastication (eating), which simulates the voluntary, nonstress behavioral state muscle activity. The results indicate that the normal safety mechanism that controls muscle fiber recruitment is absent in subjects experiencing emotional stimulation. This finding supports the theory that TMD pain is the result of muscle fiber damage due to hyper-stimulation of fast-fatiguing muscle fiber during a stress state.