Temperature Is Sufficient to Condition a Flavor Preference for a Cold-Paired Solution in Rats

摘要

Increasing evidence suggests that stimulus temperature modifies taste signaling. However, understanding how temperature modifies taste-driven behavior is difficult to separate as we must first understand how temperature alone modifies behavior. Previous work has suggested that cold water is more rewarding and "satiating" than warm water, and water above orolingual temperature is avoided in brief-access testing. We explored the strength of cold water preference and warm water avoidance by asking: (1) if cold temperature alone was sufficient to condition a flavor preference and (2) if avoidance of warm stimuli is driven by novelty. We addressed these questions using custom-designed equipment that allows us to monitor and maintain solution temperatures. We conducted two-bottle preference tests, after pairing Kool-Aid flavors with 10 or 40 degrees C. Rats preferred the flavor paired with cold temperature, both while it was cold and for 1 day while solutions were presented at 22 degrees C. We then examined the role of novelty in avoidance of 40 degrees C. Rats were maintained on 10, 22, or 40 degrees C water in their home cage to increase familiarity with the temperatures. Rats were then subject to a series of brief-access taste tests to water or sucrose at 10 to 40 degrees C. Rats that had 40 degrees C experience licked more to 40 degrees C water, but not sucrose, during brief-access testing. In a series of two-bottle preference tests, rats maintained on 40 degrees C water had a decreased preference for 10 degrees C water when paired opposite 40 degrees C water. Together, these data contribute to our understanding of orosensory-driven behavior with water at different temperatures.