Michael R. Best - US grants

When a disinctively flavored food or drink is followed by gastrointestinal distress, similarly flavored edibles are subsequently avoided. This phenomenon is generally known as taste-aversion learning. Taste-aversion learning occurs in a variety of species, including humans, nonhuman primates, rodents, and birds. Such learning is distinguished by its strength. For example, one pairing of a taste with illness is often sufficient to condition a lasting aversion to the taste, and substantial aversions usually can be conditioned when the taste and illness are separated by minutes or even hours. Dr. Best's experiments investigate how taste-aversion learning is related to the environmental context in which it occurs. He has found, for example, that rats will not drink familiar fluids-- fluids they would readily consume in other contexts--in an environment in which taste-aversion conditioning has occurred. This indicates that environments as well as distinctive flavors become associated with illness. In addition, Dr. Best has found that an environmental context can provide information about where a distinctive taste should be avoided without the context itself being associated with illness. That is, edibles tested in one environment correlated with illness but also consumed in another "safe" environment will be avoided only in the "dangerous" context. Moreover, in this procedure the only taste avoided in the dangerous context is the one paired with illness there. This indicates that, depending on the circumstances, environments can be associated with the aversive consequences of ingestion or simply signal the location in which a taste should be avoided. The primary focus of Dr. Best's new experiments is to determine the factors distinguishing these two phenomena. Both of these phenomena, as well as the processes producing them, have significant implications for human health. Understanding the role of the basic conditioning processes underlying each should provide insight into some side effects of chemo- and radio-therapy in cancer patients. Many of these people become nauseous from such therapy regimens and subsequently develop aversions to the environments in which the treatments took place. Dr. Best's research can both elucidate the processes underlying these environmental aversions and provide alternatives for reducing their occurrence.