Schedule induced eating in water deprived rats

Learning & behavior, 2016

Schedule-induced drinking has been a theoretical question of concern ever since it was first described more than 50 years ago. It has been classified as adjunctive behavior; that is, behavior that is induced by an incentive but not reinforced by it. Nevertheless, some authors have argued against this view, claiming that adjunctive drinking is actually a type of operant behavior. If this were true, schedule-induced drinking should be controlled by its consequences, which is the major definition of an operant. The present study tested this hypothesis. In a first experimental phase, a single pellet of food was delivered at regular 90-s intervals, but the interfood interval could be shortened depending on the rat's licking. The degree of contingency between licking the bottle spout and hastening the delivery of the food pellet was 100 %, 50 %, and 0 % for 3 separate groups of animals. Rats that could shorten the interval (100 % and 50 % contingency) drank at a higher rate than those...

Food anticipatory activity (FAA) is the expression of a food entrained oscillator, which manifests under restricted feeding schedules (RFS). Food restriction to 2 h daily represents a metabolic challenge and requires behavioral and physiological adaptations in order to allow animals to ingest sufficient food for a 24 h cycle in a short 2 h interval. In order to characterize the behavioral and physiological adaptations during restricted feeding, rats were maintained for 3 weeks under a fixed RFS, an unpredictable RFS and ad libitum (AL) feeding conditions. Feeding behavior was recorded for 2 h during meal access for RFS groups and during the first 2 h of the dark period in AL controls. Body and stomach weight were also measured for the three feeding groups. There was a significant difference between restricted groups and AL controls in the latency and duration of feeding during the 2 h of food access. Restricted rats which could predict mealtime showed the shortest latency. In both RFS groups the stomach attained a large distension in contrast to AL controls, and total time spent in food ingestion was 3-4 fold higher than the AL. However, and despite these behavioral and physiological adaptations, restricted rats did not achieve a body weight gain at the end of the experiment, unlike the AL group. Present data indicate that during RFS rats develop behavioral and physiological adaptations to ingest increased amounts of food in a short interval.

Physiology & behavior, 1980

Journal of the Experimental Analysis of Behavior, 1995

Food-deprived rats (at 80% of their free-feeding weights) were exposed to a fixed-time 60-s schedule of food-pellet presentation and developed schedule-induced drinking. Lick-dependent signaled delays (10 s) to food presentation led to decreased drinking, which recovered when the signaled delays were discontinued. A major effect of this punishment contingency was to increase the proportion of interpellet intervals without any licks. The drinking of yoked control rats, which received food at the same times as those exposed to the signaled delay contingency (masters), was not consistently reduced. When food-deprivation level was changed to 90%, all master and yoked control rats showed decreases in punished or unpunished schedule-induced drinking. When the body weights were reduced to 70%, most master rats increased punished behavior to levels similar to those of unpunished drinking. This effect was not observed for yoked controls. Therefore, body-weight loss increased the resistance of schedule-induced drinking to reductions by punishment. Food-deprivation effects on punished schedule-induced drinking are similar to their effects on food-maintained lever pressing. This dependency of punishment on food-deprivation level supports the view that schedule-induced drinking can be modified by the same variables that affect operant behavior in general.

Journal of the Experimental Analysis of Behavior, 2013

Under intermittent food schedules animals develop temporally organized behaviors throughout interfood intervals, with behaviors early in the intervals (interim) normally occurring in excess. Schedule-induced drinking (a prototype of interim, adjunctive behavior) is related to food deprivation and food frequency. This study investigated the interactions that resulted from combining different food-deprivation levels (70%, 80% or 90% free-feeding weights) with different food-occurrence frequencies (15-, 30-or 60-s interfood intervals) in a within-subjects design. Increases in food deprivation and food frequency generally led to increased licking, with greater differences due to food deprivation as interfood intervals became shorter. Distributions of licking were modestly shifted to later in the interfood interval as interfood intervals lengthened, a result that was most marked under 90% food deprivation, which also resulted in flatter distributions. It would therefore appear that food deprivation modulates the licking rate and the distribution of licking in different ways. Effects of food deprivation and food frequency are adequately explained by a theory of adjunctive behavior based on delayed food reinforcement, in contrast to alternative hypotheses.

Behavioural Processes, 2010

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Psychological Record, 2000

Three food-deprived rats (80% of their free-feeding weights) developed schedule-induced drinking after being exposed to a multiple fixed-time schedule (FT 60-s FT 18-s) of food-pellet presentation. A 3-s signaled delay was then initiated by each lick, and the rate of licking was reduced to a much greater extent in the FT 18-s component in two rats. With these rats, a 9-s lickdependent signaled delay then occurred in the FT 60-s component only, and a reduction was observed in licks per minute similar to that observed previously with the 3-s delay in the richer component. With the third rat the delays which were effective in reducing licking were 6 and 18 s in the FT 18-s and FT 60-s components, respectively. Measures of the percentage of interfood intervals with at least one lick produced less pronounced effects. These results suggest that the ratio between delay length and interfood interval length is critical for lick-dependent delays to be effective in punishing schedule-induced drinking. found that food-deprived rats exposed to a variableinterval schedule (VI 1-min) of food reinforcement drank excessive amounts of water concurrently with their performance of the operant task. This behavior is unusual because the rats were not deprived of water and no contingency was arranged between their drinking and the delivery of food. suggested that this schedule-induced polydipsia was the prototype of a behavioral class named "adjunctive behavior;' different from operant behavior. The amount of schedule-induced behavior is related to the parameters that define the food reinforcer, such as its magnitude or quality, the rate at which food is presented, or the animal's level of food deprivation (see reviews by .

Physiology & Behavior, 1981

Failure of periodic presentation of palatable diet to entrain feeding, drinking and activity rhythms under constant conditions. PHYSIOL. BEHAV. 27(6) 1057 -1066 , 1981 drinking and activity of two groups of male laboratory rats were studied across three experimental stages: LD 12:12; LL; and LD 12:12. In the first group (Control), ordinary diet was available ad lib for the entire experiment. In the second group (Experimental), palatable diet was available for the first 12 hr of each day and ordinary diet for the remainder of the day in stages 2 and 3. It was found that in stage I all behaviors were highly nocturnal. The nocturnality of feeding was achieved by the ingestion of more meals in the D phase as compared to the L phase. Dark ingested meals were not significantly larger than meals in the L phase. In stage 2, circadian rhythms in all three variables were damped and meals became evenly spaced across the day in both groups. In the Control group, meal sizes were also of the same magnitude across the day. However, periodic presentation of palatable diet resulted in larger meals and, therefore, the ingestion of 60% of total daily food intake during the 12 hr period when palatable food was available. Total daily food intake in LL did not change compared to stage 1 and did not differ between the groups. The size and number of significant meal size/post-meal interval correlations increased over the duration of the experiment but remained relatively small. In stage 2, water intake and activity were similarly evenly distributed over the 24 hr period in both groups and were not influenced by periodic presentation of palatable diet. No marked decreases in total daily water intake, but a substantial decrease in daily activity, were found. Under LL, daily body weight increments in both groups were maintained, but subtle changes were observed. In stage 3 when the LD cycle was reinstated, both groups ate a greater number of meals in the D phase despite the availability of palatable food in the L phase for the Experimental group. These animals ate fewer but larger meals of palatable diet than ordinary food resulting in 50% of their daily intake being ingested during the L phase. Activity and water intake returned to stage 1 levels and the distributions of these behaviors were similar to those found in stage 1 in both groups. It was concluded that palatable diet influenced meal size only and that the timing of meals depended on the illumination conditions only. Further, periodic presentation of palatable diet failed to entrain the damped rhythms of feeding, drinking and activity in LL. These results do not rule out the possibility that such an entraining effect of periodic presentation of palatable diet might be found in conditions of DD.

American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 2005

Attempts to understand ingestion have sought to understand the control of meals. The present study evaluated a meal definition that included prandial drinking (drinking-explicit meals). The spontaneous nocturnal intake of male Wistar rats was studied. The meal breakpoint was defined as the interval between feeding or drinking events providing the most stable estimate of meal structure. Alternative breakpoints derived from prevailing methodology, log-survivorship, or frequency histogram analysis of interfeeding intervals without respect to drinking were compared (drinking-naive meals). Threshold interfeeding intervals that accounted for drinking indirectly were evaluated as surrogate breakpoints (drinking-implicit meals). Definitions were compared by determining which criterion better conformed to predictions of satiety. Microstructural differences resulting from the definitions were also studied. Under the drinking-explicit definition, rats averaged nine or ten 13-min meals/night, d...

Netherlands Journal of Zoology, 1980

Two experiments are described about the alternation of eating and drinking behaviour in rats. In experiment 1 there were three conditions where the eating system dominated the drinking system, and two conditions where the drinking system dominated the eating system. Experiment 2 replicated the condition with the eating system dominating the drinking system. The aim of the study was to investigate the existence of a time-sharing mechanism which regulates the alternation of eating behaviour and of drinking behaviour. Timesharing means, according to McFarland, that the dominating behavioural system alternately inhibits and disinhibits the subdominant behavioural system. We partly confirmed the hypothesis that a time-sharing mechanism is operating, but the mechanism operates only during the first, small, part of the thirty minutes observation period. Despite the strong alternation of eating and drinking the total duration of eating or of drinking was similar in any condition, but the frequency of bouts varied. Exploratory behaviour occurred frequently in the pauses between eating and drinking bouts.