Rhythm generation for food-ingestive movements.

In vitro block preparations of the central nervous system (CNS) are particularly valuable for study of central neuronal mechanisms controlling the respiratory and locomotor rhythms. No comparable in vitro preparation has been described previously, however, for analysis of analogous feeding rhythms. In this chapter, we present such a model. It is comprised of an in vitro brainstem-spinal cord preparation isolated from the newborn rat and mouse. Bath application to this preparation of N-methyl-D-aspartate (NMDA) induces rhythmical burst activity in the V, VII and XII nerves, which, collectively, is indicative of feeding behavior. Selected transections of the brainstem reveal that the central sucking rhythm generators for such V, VII and XII activity are separate from one another, and located segmentally in the brainstem at the level of their respective motor nuclei. We believe that use of this in vitro preparation will advance understanding of the central neuronal mechanisms controlling sucking and mastication, and the developmental transition from sucking to mastication.