Effects of lick-contingent timeout on schedule-induced polydipsia

Area of Science:

• Behavioral Neuroscience
• Animal Behavior

Background:

• Rats exhibit schedule-induced polydipsia (excessive drinking) when food reinforcement is intermittent.
• Water availability can exacerbate this behavior, leading to excessive water intake.

Purpose of the Study:

• To investigate the effects of lick-contingent timeout periods on schedule-induced polydipsia in rats.
• To determine if interrupting the food reinforcement schedule during timeout influences drinking behavior.

Main Methods:

• Rats were trained on a fixed-interval schedule of food reinforcement and concurrently had water available.
• Lick-contingent timeout periods were introduced, during which lever pressing for food was disabled.
• Timeout duration was logarithmically increased (10-80 seconds), with conditions varying whether the food schedule timer continued or paused.

Main Results:

• Increasing timeout duration generally decreased lick rates and water intake.
• Licks that initiated timeouts decreased with longer timeout durations.
• Licks during ongoing timeouts remained relatively constant.
• Water intake and lick rates were more suppressed when timeouts paused the food schedule timer.

Conclusions:

• Lick-contingent timeouts effectively reduce schedule-induced drinking in rats.
• The suppressive effect is amplified when timeouts increase the interreinforcement interval, disrupting the food schedule.