Production and regulation of ingestive consummatory behavior in the chronic decerebrate rat

Abstract

A given taste does not always elicit the same response be it ingestion or rejection. Rather, the afferent-efferent relationships yielding these responses are regulated by neural signals deriving from the organism's physiological state and experience. By examining preparations with increasing degrees of ablation, it is not only possible to establish the neural boundary conditions for the production of ingestive consummatory behavior but also for its regulation. A comparison of the capacity of brain levels for regulating palatability provides an alternative approach to the prevalent single integrator hypothesis. Ablated preparations, like chronic decerebrate rats, do not spontaneously eat or drink. Nevertheless, we have developed methodologies for examining the topography of ingestion and rejection responses and fluid intakes of decerebrate rats. Using these methods we have shown that the discriminative responses to tastes of decerebrates do not differ from those of intact rats. The decerebrate rat can not only produce ingestive consummatory responses, but can also regulate these responses as a function of deprivation-repletion. This demonstration coupled with the evidence for sympathoadrenal function in the decerebrate rat leads us to conclude that neural mechanisms caudal to the forebrain are sufficient for production of ingestive consummatory responses as well as aspects for its regulation.