Schedule-induced drinking session as an intruded event within a 24-hour period

Abstract

The schedule-induced drinking procedure (SID) typically involves two different operations; one, depriving rats of food in their home cages and two, delivering food pellets at intervals during the experimental sessions. These procedures reliably result in the rats drinking a substantial volume of water during the session. In the present experiment each SID session was added during a 24 hour observation period. This allowed the observation of drinking before, during, and after each SID session. While food was not available at any time during 22.5 hours a day, during the one-hour SID session a 180-s fixed-time schedule delivered four- 25 milligram food pellets per feeder operation until a total of two grams were delivered. On alternate days the rats were placed in their home cages and given the amount of food necessary to keep them at 80% of their free- feeding weight. Results showed that on experimental days drinking occurred infrequently when food was withheld and concentrated within the SID session, when food was delivered according to the reinforcement schedule. This experiment shows that SID can be seen as a procedure that controls the rats distribution of their daily drinking so that drinking concentrates during the experimental session.