Differential controls of small and large motor unit activity in the masseter muscle with incisal stimulation in humans.
The activity of masseter motor units with different spike amplitudes was recorded and reflex responses by force stimulation of an incisor were analyzed in humans. The effects of reflex responses varied depending on the level of prestimulus firing frequency (background activity, BGA). When small amplitude motor units and large amplitude motor units were tested at the same level of BGA, the former tended to exhibit excitatory reflexes and the latter inhibitory ones.
Yamamura
C
C
Department of Oral Physiology, Niigata University School of Dentistry, Japan.
Shimada
K
K
D000200:Action Potentials; D000328:Adult; D004558:Electric Stimulation; D006801:Humans; D007180:Incisor / Q000294:innervation*; D008297:Male; D008406:Masseter Muscle / Q000294:innervation*; D009046:Motor Neurons / Q000502:physiology*; D012018:Reflex / Q000502:physiology*