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| International Symposium - Schedule-Induced Drinking Reduces to Operant Conditioning: Some Follow-Up Studies |
| Saturday, May 26, 2007 |
| 1:00 PM–2:20 PM |
| Madeleine AB |
| Area: EAB; Domain: Basic Research |
| Chair: Carlos A. Bruner (National Autonomous University of Mexico) |
| Abstract: Based on the idea that schedule-induced drinking (SID) by rats may be reduced to the operant reinforcement of the water-producing response, during the last six years our research group has pursued two lines of inquiry in the study of SID. One is that the water-producing response can be used to replicate different operant conditioning phenomena. In this symposium the papers by Ruiz and Lopez follow this strategy. Ruiz shows that delaying water reinforcement has the same effects on the water-producing response than on any other operant. The paper by Lopez shows that responding for water can be subjected to a discrimination also like any other operant response. Our second line of inquiry concerns the question of why water, freely available in the rats homecages, becomes a reinforcer during the typical SID session. The papers by Diaz and Roca address this question. Diaz shows that the alternation between eating and drinking bouts, so distinctive of SID, occurs as part of the natural feeding pattern of rats, even when food and water are freely available. The paper by Roca further pursues the correlation between eating and drinking under conditions of food deprivation. The paper by Roca shows that hungry rats drink when there is food and rarely in its absence. Also that their intake is proportional to the amount of food given, regardless of the temporal distribution of food. |
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| Delay of Water Reinforcement in a Schedule-Induced Drinking Procedure. |
| JORGE A. RUIZ (National Autonomous University of Mexico), Carlos A. Bruner (National Autonomous University of Mexico) |
| Abstract: The purpose of this study was to determine the effect of lengthening the duration of a water reinforcement delay on the response which produces water in a schedule-induced drinking procedure. Three food-deprived rats were exposed to a schedule of water reinforcement tandem Fixed Ratio (FR) 1 Fixed Time (FT) t s. In successive conditions the FT duration was 0, 1, 2, 4, 8, 16 and 0 s. During all conditions food was delivered according to a Random Interval 64 s. It was found that the number of responses per water decreased gradually as the water reinforcement delay was lengthened and that this effect was reversed when the rats were exposed in a second time to immediate reinforcement (FT 0 s). These results suggest that behavior which produces water in a schedule-induced drinking procedure is sensitive to the parameters of reinforcement documented in operant conditioning and raise a question about the interpretation of schedule-induced drinking as a third class of behavior. |
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| Stimulus Discrimination in a Schedule-Induced Drinking Procedure. |
| CHRISTIAN LOPEZ GUTIERREZ (National Autonomous University of Mexico), Carlos A. Bruner (National Autonomous University of Mexico) |
| Abstract: Most previous attempts to condition schedule-induced drinking (SID) to neutral stimuli have involved classical-conditioning procedures, with mixed results. According to the hypothesis that SID reduces to the operant reinforcement with water of the water-producing response, an attempt was made to establish stimulus control on drinking using an operant discrimination procedure. Two different experiments were conducted with food deprived rats lever pressing for water on mixed and multiple water-reinforcement schedules. In both experiments, responding produced water in the 32-s reinforcement component on a 6-s random interval schedule. Also in both experiments, food pellets were delivered concurrently on a 64-s random time schedule. For the three rats in Experiment 1, the duration of the extinction component was 64 s while in Experiment 2 the duration of the extinction component was either 16 or 256 s for three rats each. An operant discrimination was formed when the extinction component was either 64 or 256 s but not when it was 16 s. In addition, discrimination indexes increased as the extinction component was lengthened. These results show that SID can be subjected to an operant discrimination and that such discrimination follows the principle of relative time. Together, these results support the idea that SID reduces to operant principles. |
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| Feeding and Drinking by Rats with Free Access to Food and Water. |
| FELIPE RESENDIZ DIAZ (National Autonomus University of Mexico), Carlos A. Bruner (National Autonomus University of Mexico) |
| Abstract: Survival Analysis was used to examine the interaction between feeding and drinking bouts in rats with free access to food and water. Successive bouts were subjected to a conditional probability analysis showing that rats alternate more frequently between eating and drinking than between any other combination of events. The latencies between successive eating and drinking bouts showed that drinking bouts occurred closer in time to the preceding than to the subsequent eating bout. Given that rats alternate between eating and drinking under free access to food and water it is possible that the Schedule-Induced Drinking procedure only accentuates the alternation between eating and drinking given the intermittent delivery of food and food deprivation. |
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| How Does the Schedule-Induced Drinking Procedure Endow Water with Reinforcing Value? |
| ALICIA ROCA (National Autonomous University of Mexico), Carlos A. Bruner (National Autonomous University of Mexico) |
| Abstract: Food deprived rats reduce their water intake and the reintroduction of food reestablishes normal drinking. Could drinking track food availability in the schedule-induced drinking (SID) situation? Drinking really depends on temporally-spaced food availability? Does the amount of food per serving determine the magnitude of drinking? The following experiments addressed these questions. Three food-deprived rats resided 24/7 in their individual experimental chambers. On successive 30-day conditions access to food was varied. In the first condition, three one-hour SID “sessions” were intruded into the experimental day. A fixed-time 180-s schedule delivered either 1, 3, or 8 grams worth of food pellets in each session. In the second condition 1, 3 or 8 grams of pellets were delivered altogether at the beginning of each of the three SID sessions. In the third condition 12 grams of pellets were delivered altogether at the beginning of the experimental day. Answering the questions above, rats only drank during the “sessions”, when food was present; water intake by each rat remained constant regardless of food distribution; the volume of water drunk by each rat correlated positively with the amount of food served per occasion. These data suggest that the reinforcing value of water for hungry rats in the typical SID situation depends on the availability of food. |
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