| Abstract: | The effects of electrical stimulation of the rat's contralateral frontal cortex as well as bilateral central amygdaloid nuclei were examined on the masseteric and mylohyoid-anterior digastric motoneurons which innervate a jaw closing muscle and jaw opening ones, respectively.Thirty-six percent of masseteric motoneurons were inhibited and 14% were facilitated by stimulation of the cortex and the central amygdaloid nucleus. Fifteen percent were inhibited or facilitated by either stimulation, although 36% were unaffected. No masseteric motoneuron was facilitated by one, stimulation and inhibited by the other.A majority of mylohyoid-digastric motoneurons were facilitated by stimulation of the cortex and the central amygdaloid nucleus although 17% were facilitated by either stimulation and 17% were unaffected. No mylohyoid-digastric motoneuron was inhibited.Therefore, the frontal cortex and the central amygdaloid nucleus have convergent control of jaw movements primarily in the opening direction. |
