PART II. PHYSIOLOGICAL SUBSTRATES OF CONDITIONED FOOD AVERSIONS: Introduction: Physiological Mechanisms in Conditioned Taste Aversions a

The behavioral effects of associating a taste with visceral malaise are rapid and dramatic. Following this association, animals avoid consuming a taste which they had once readily consumed. In conceptualizing the physiological mechanisms responsible for the production of this conditioned taste aversion (CTA) we should consider how the central nervous system (CNS) integrates taste and visceral stimuli and within which of its structures this integration takes place. This integration(s) changes the animal’s response to the paired taste stimulus and to other tastes that are processed similarly by its nervous system. The physical properties of the taste stimulus have not changed, yet due to the association, the neural coding of the taste has been altered to yield an opposite response. The factors integrated by the CNS derive from the peripheral and central gustatory system, peripheral and central afferent systems sensitive to emetic stimuli, and hormones and neurotransmitters that modulate the excitability of both central synapses and even perhaps the taste receptors themselves, if there are ancillary aspects to this neural integration. The five papers in the physiological section of this book focus on separate aspects of this central integration problem, though none has focused on the sites of action of, and neural channels mediating, the variety of agents that can function as USs in CTAs. I will discuss some issues raised by these papers, as well as material of my own, in a topic format.