Schedule-induced drinking: Elicitation, anticipation, or behavioral interaction?

Area of Science:

• Behavioral Neuroscience
• Animal Behavior
• Operant Conditioning

Background:

• Schedule-induced polydipsia is a phenomenon where animals increase drinking behavior under specific food reinforcement schedules.
• Previous research has explored the relationship between food delivery schedules and drinking patterns, with varying explanations.
• Understanding the precise triggers and mechanisms of schedule-induced drinking is crucial for behavioral science.

Purpose of the Study:

• To investigate the relationship between individual food-pellet presentations and drinking behavior in rats.
• To determine if food presentations or associated stimuli elicit schedule-induced drinking.
• To explore the role of dynamic behavioral interactions in schedule-induced drinking.

Main Methods:

• Five experiments were conducted using rats maintained on fixed-time (FT) food schedules.
• Experiments involved presenting unsignaled and signaled extra food, observing drinking patterns before and after presentations.
• Drinking persistence was assessed after consecutive intervals ending with extra food; food delivery magnitude was varied across sessions.

Main Results:

• Schedule-induced drinking was not elicited by food presentations or stimuli associated with a high food rate.
• Rats prioritized food-related behaviors over drinking when presented with stimuli signaling an increased local probability of food delivery.
• Drinking patterns were modified by the persistence of extra food delivery across intervals.

Conclusions:

• Schedule-induced drinking is not a direct effect of food reinforcement contingencies but arises from dynamic interactions between behaviors.
• Rats exhibit a rule-based behavior, prioritizing food acquisition over drinking when food availability increases.
• The findings challenge simple elicitation or induction models, highlighting the complexity of motivated behavior under reinforcement schedules.