Differentiation of the neural pathways mediating cortically induced and dopaminergic activation of the central pattern generator (CPG) for rhythmical jaw movements in the anesthetized guinea pig

Abstract

The central pattern generator (CPG) for rhythmical jaw movements (RJMs) was activated, in the anesthetized guinea pig, by systemic injection of a specific dopamine agonist, apomorphine (APO). It was shown that APO induced RJMs required an intact superior colliculus, and were blocked by low doses (0.05–1.0 mg/kg) of haloperidol (HAL), a dopamine antagonist. This is in contrast to the neural pathways mediating RJMs evoked by repetitive electrical stimulation of the masticatory cortex which remained effective following both lesions of the superior colliculus and administration of HAL. These results suggest that there are at least two anatomically separate and pharmacologically distinct command centers for activation of the CPG for RJMs in the guinea pig.