DYE-COUPLING BETWEEN VAGAL MOTONEURONS WITHIN THE COMPACT REGION OF THE ADULT-RAT NUCLEUS AMBIGUUS, IN-VITRO

The electrophysiological and morphological characteristics of vagal motoneurones lying within the compact region of the nucleus ambiguus were investigated in thin coronal slices of the adult rat medulla utilising intracellular recording techniques. The majority of neurones were found to be silent, displaying no underlying synaptic activity or oscillations in membrane potential. Intracellular dye-filling demonstrated that the neurones had multipolar cell bodies, with 2-8 major dendrites, each branching up to 4 times and extending up to 200 mu m from the cell body. The existence of dye-coupling between adjacent neurones was shown in 30% of cells investigated. This evidence suggests a possible mechanism for the provision of synchronous activity within groups of vagal motoneurones, a process essential for the control of deglutination.