Rhythmical jaw movements and lateral ponto-medullary reticular neurons in rats.

Neuronal activity in the lateral reticular formation was investigated in urethane-anesthetized rats. Stimulation of anterior and posterior cortical areas induced two types of rhythmical jaw movements (RJM). The effects of stimulation of these cortical areas, the peripheral nerves, and the trigeminal motor nucleus on these neurons and their activity during the RJM were analyzed. The smallest percentage of neurons receiving anterior cortical input received peripheral input, and most neurons with posterior cortical input received peripheral input. Sixty per cent of reticular neurons showed the rhythmical firing closely related to the RJM. Therefore, these neurons may participate in masticatory pattern formation.