Chapter 5 Vagal efferent projections: viscerotopy, neurochemistry and effects of vagotomy

Abstract

This chapter focuses on the viscerotopic organization of the cells of origin of the vagus nerve with emphasis on subnuclear organization in the vagus nerve (DMV) and nucleus ambiguus (AMB). Aspects of the neurochemistry and afferent inputs of the DMV and AMB are discussed in terms of the identified viscerotopic organization. The effects of vagus nerve lesions will be assessed in terms of subnuclear differences as they relate to the connectivity connectivity and neurochemistry of the DMV and AMB. The chapter shows that the viscerotopic representation in the two nuclei comports with topographic patterns of specific neurochemicals and that vagal lesions cause differential responses in chemically and functionally distinct groups of neurons in the DMV and AMB. Neurochemical changes following vagal lesions are selective for specific viscera and are not uniform among functional subdivisions in the two nuclei. The viscerotopic organization of vagal motoneurons, thus, may also be reflected in differences in trophic support and pathophysiology.