Context dependent changes in the reinforcing strength of schedule-induced drinking

Area of Science:

• Behavioral neuroscience
• Animal behavior

Background:

• Schedule-induced behavior, including polydipsia (excessive drinking), is known to be reinforcing.
• Understanding the factors that modulate the reinforcing strength of such behaviors is crucial for behavioral science.

Purpose of the Study:

• To quantify the reinforcing strength of schedule-induced drinking in rats.
• To investigate the relationship between food reinforcement schedules and polydipsic drinking behavior.

Main Methods:

• Four rats were trained on a concurrent-chain schedule with fixed-time food delivery in terminal links.
• One terminal link offered access to a water dipper, inducing polydipsic drinking.
• Button-pressing rates for water were recorded and analyzed in relation to food pellet rates.

Main Results:

• Rats exhibited polydipsic drinking in the presence of the water dipper.
• The rate of button presses for water followed a bitonic function of the food pellet rate.
• A modified matching equation successfully described the relationship between food and water reinforcement.

Conclusions:

• The reinforcing strength of schedule-induced polydipsia is significantly influenced by the rate of concurrent food reinforcement.
• Water availability did not affect initial-link response rates, suggesting specific modulation of terminal-link behavior.
• The reinforcing effects of polydipsia are context-bound, strongly associated with periodic food reinforcement schedules.