[Action potentials of cat masseter muscle motor neurons evoked by stimulation of low-frequency infraorbital nerve afferents].

The responses of masseter motoneurons evoked by stimulation of the low-threshold infraorbital afferents by different number of stimuli were investigated in cats under chloralose-nembutal anesthesia. It is shown that 3-4 succesive stimuli (1.2 of threshold) evoked action potentials in masseter motoneurons if their frequency was above 300/s. Stimulation of the infraorbital nerve by paired stimuli produced action potentials in these motoneurons when the interval between the stimuli was 1.3-4.0 ms. With longer intervals only facilitation of the second EPSP was observed, the degree of facilitation varying from 0.2 to 1.0. A conclusion is made that the masseter motoneurons discharges can be produced by activation of the infraorbital nerve. A -fibres probably connected to rapidly adapting receptors of the vibrissae.