title: Amygdaloid and cortical facilitation or inhibition of trigeminal motoneurons in the rat.
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.
mesh_terms: D000679:Amygdala / Q000502:physiology*; D000818:Animals; D001931:Brain Mapping; D005625:Frontal Lobe / Q000502:physiology*; D008410:Masticatory Muscles / Q000294:innervation; D009046:Motor Neurons / Q000502:physiology*; D009433:Neural Inhibition; D009434:Neural Pathways / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D009435:Synaptic Transmission; D014276:Trigeminal Nerve / Q000502:physiology*