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W Timberlake

Publications and source records attributed to W Timberlake.

At least 19 recordsLinked to original sources
PubMed2000

Facilitation of preparatory behavior in an artificial prey paradigm by D1-subfamily dopamine receptor activation.

Dopamine agonists facilitate, and antagonists inhibit, conditioned preparatory behaviors in rats. Similar effects are demonstrated on an unconditioned preparatory behavior: predatory search and contact of a moving artificial prey stimulus. Apomorphine (0.1, 0.2 mg/kg), a direct agonist, had no effect relative to a within-subject injection of saline vehicle but d-amphetamine (0.1 mg/kg), an indirect agonist, increased contact frequency without altering overall motor activation. To determine the relative importance of the D1 and D2 subfamilies of receptors in the amphetamine effect, separate groups of animals received amphetamine co-injected with either SCH23390 (0.01 and 0.005 mg/kg) or eticlopride (0.01 mg/kg), D1 and D2 antagonists, respectively. Whereas the eticlopride-amphetamine group showed no change in contact frequency from baseline, co-injections of either dose of SCH23390 and amphetamine led to near total suppression of contact, as did treatment with SCH23390 (0.005 mg/kg) alone. Treatment with 0.01 mg/kg eticlopride alone increased contact frequency while treatment with a higher dose (0.1 mg/kg) had no effect. Treatment with the D1-subfamily agonist SKF81297 (0.1 mg/kg) increased contact frequency. Collectively, these results support the hypothesis that dopamine mediates unconditioned preparatory behavior and suggest differing roles for the D1 and D2 receptor subfamilies.

Amphetamine↗
PubMed1998

Circadian activity precedes daily methamphetamine injections in the rat.

Scheduled daily injections of methamphetamine (MA) produced locomotor activity that preceded and followed the usual time of injection in rats housed under conditions of constant, moderately dim light and temporally distributed feeding. A circadian basis for pre-injection time activity was supported by its anticipatory timing in the apparent absence of reliable preceding external cues and by its persistence on a test day on which the rats remained undisturbed. Post-injection time locomotor activity also persisted on the test day, occurring from 24 to 29 h after the final MA injection. These results indicate that MA injections engage circadian processes underlying locomotor activity, and they raise the possibility that intake of drugs of abuse by humans may facilitate drug taking or relapse at times of day related to previous drug use.

Animals↗
PubMed1995

Two meals promote entrainment of rat food-anticipatory and rest-activity rhythms.

Ten female rats were fed early and late in the dark period of a 12-12 h light-dark cycle and then were fed at the same times in constant darkness. In both conditions rats were active prior to mealtimes and manifested no free-running components of activity. When the rats were placed in constant darkness and either were fed early and late in the inactive period, or had free access to food, six of the rats had rest-activity rhythms different from 24.0 h. Though a masking explanation could not be ruled out, two meals during the active period apparently entrained the rest-activity rhythms of these rats. The light-entrainable oscillator appears to integrate information from cycles of both illumination and food availability. Multiple sources of temporal information may promote more stable entrainment of the rest-activity rhythm than the light-dark cycle alone, especially in a burrow dwelling organism, like the rat, that can be exposed to inconsistent light-dark transitions.

Animals↗
PubMed1995

Two possible determinants of the timing of daily episodes of behavior in rats.

The present experiment examined endogenous ultradian rhythms and regulatory metabolic processes as two potential determinants of daily out-of-nest episodes (ONEs) and feeding episodes (FEs) in rats living in a 24-h environment. Two types of photoperiod were used: a Standard 12:12 h L/D schedule and a Skeleton 12:12 h schedule. During each type of photoperiod rats were exposed to 4 feeding conditions of 7 to 12 days each: (a) a baseline of ad lib food and water; (b) restricted to the diurnal (inactive) portion of the cycle; (c) both food and water restricted to the inactive period; and (d) return to baseline. Time series analyses of nocturnal ONEs in baseline revealed a strong circadian rhythm and weaker ultradian rhythms with periods between 2 and 6 h. Analyses of FEs, though, revealed a general absence of circadian rhythms but strong ultradian rhythms with periods similar to those observed in ONEs. When food and water were restricted to the inactive part of the cycle, ONEs showed no change in frequency, but a decrease in average duration and changes in ultradian periodicities. The results indicated control of daily episodes of behavior in rats by ultradian oscillators that are weaker and more variable in affect than those found in voles, but similar in period.

Animals↗
PubMed1995

Decremental carryover effects of sucrose ingestion in the negative anticipatory contrast procedure in rats.

To test for retrospective effects of sucrose ingestion in the anticipatory contrast procedure, 4 experiments examined intake of an initial 0.15% saccharin solution as a function of the unsignaled interspersing of days in which the 2nd solution was 32% sucrose or 0.15% saccharin. In Experiment 1, rats that received alternating saccharin-saccharin days and saccharin-sucrose days drank less saccharin on saccharin-only days, and on both days they drank less saccharin than a control group that received saccharin only. In Experiment 2, rats that received randomized saccharin-saccharin and saccharin-sucrose days drank less saccharin if, and only if, a sucrose day preceded. Experiments 3 and 4 used double and quadruple alternation of saccharin and sucrose days to examine persistence of the effects of a sucrose day. The results highlighted a retrospective carryover effect of sucrose that reduced intake of the initial saccharin solution and apparently was based on sucrose memories persisting over days.

Animals↗
PubMed1994

Two meals in the active period of the rat both entrain food-anticipatory activity.

We examined the effect of presenting two meals at fixed times on the activity of six intact female rats. Rats maintained on a 12-12 h light-dark cycle were fed: ad lib, at two randomly chosen times during the active period, and at 3 and 9 h, 1 and 7 h, and 5 and 11 h after light offset. During ad lib and random feeding conditions, wheel turning primarily occurred during the first half of the active period. During fixed-time feeding conditions, wheel turning was concentrated around the times of meal availability. To determine whether anticipatory wheel turning during fixed-time feeding conditions was based on a circadian mechanism, each condition was followed by a test: light cues omitted and rats were deprived of food for 2 consecutive days. Wheel turning patterns observed while a feeding condition was in effect persisted during meal omission. Nest and food/water compartment visits were not as sensitive to feeding times. Meals may have modified bouts of activity that are also synchronized by light-dark cycles.

Animals↗
PubMed1993

Behavior systems and reinforcement: an integrative approach.

Most traditional conceptions of reinforcement are based on a simple causal model in which responding is strengthened by the presentation of a reinforcer. I argue that reinforcement is better viewed as the outcome of constraint of a functioning causal system comprised of multiple interrelated causal sequences, complex linkages between causes and effects, and a set of initial conditions. Using a simplified system conception of the reinforcement situation, I review the similarities and drawbacks of traditional reinforcement models and analyze the recent contributions of cognitive, regulatory, and ecological approaches. Finally, I show how the concept of behavior systems can begin to incorporate both traditional and recent conceptions of reinforcement in an integrative approach.

Animals↗
PubMed1992

Negative anticipatory contrast and preference conditioning: flavor cues support preference conditioning, and environmental cues support contrast.

In 2 experiments, access to a 0.15% saccharin solution was followed on alternating days by access to a 32% sucrose solution and the same saccharin solution. In Experiment 1, rats increased both intake of and preference for a flavored saccharin solution that predicted sucrose, but neither effect was found using a predictive odor cue alone. Experiment 2 replicated the predictive flavor results but showed suppression of saccharin intake when environmental cues predicted sucrose. When both flavor and environment predicted sucrose, saccharin intake did not change, but preference for the predictive flavor increased. Discriminative taste cues appear to facilitate the development of preference conditioning, but environmental cues favor negative anticipatory contrast effects. Also, preference conditioning and contrast may develop concurrently and compete for expression.

Animals↗
PubMed1991

Reinforcement in applied settings: figuring out ahead of time what will work.

This article reviews the practical value of conceptual attempts to specify the circumstances of reinforcement ahead of time. Improvements are traced from the transituational-reinforcer approach of Meehl (1950), through the probability-differential model of Premack (1959, 1965), to the response deprivation and disequilibrium approach (Timberlake, 1980, 1984; Timberlake & Allison, 1974). The application value of each approach is evaluated on the grounds of simplicity, accuracy, and adaptability. The article shows that the disequilibrium approach accounts for and extends current empirically driven techniques of reinforcement control and examines some of its limitations. The disequilibrium approach clarifies how current knowledge can be used to predict more accurately the circumstances of reinforcement and invites the collaboration of applied and basic research in its further development.

Behavior Therapy↗
PubMed1990

Environmental influences on flank marking and urine marking by female and male rats (Rattus norvegicus).

Sprague-Dawley rats (Rattus norvegicus) were observed in a familiar environment. In Experiment 1 a leader entered a clean chamber, and an opposite-sex follower entered the chamber next. Both sexes began to flank mark after several sessions. Males flank marked more, and females locomoted more, but both sexes urine marked and investigated objects equally often. Leaders and followers did not differ on any measure. In Experiment 2 we measured floor marks more precisely and manipulated the number of objects and the presence of scent marks. Flank marking was more frequent in the presence of conspecific urine but did not vary with the number of objects or the sex of the rats. More objects elicited more investigating and urine marking and produced fewer floor marks but increased the number of marks in the central area in relation to the periphery. The results indicate that rats' flank marking is behaviorally distinct from urine marking and differentially affected by environmental variables.

Animals↗
PubMed1990

Anticipation of future food: suppression and facilitation of saccharin intake depending on the delay and type of future food.

A series of studies examined the (Sprague-Dawley) rat's tendency to suppress intake of .15% saccharin when it was followed by a second food after 4-, 16-, or 32-min delays. The second foods examined were 32% sucrose, 64% sucrose, lab chow, a Nutrasweet solution, skim milk, and chocolate milk. Saccharin intake was influenced by both the delay and the specific food available. Subsequent analysis showed that saccharin intake before the 4-min delay was an inverse function of the caloric value of the second food. However, saccharin intake before the 16-min delay was better predicted as an inverse function of the hedonic value of the second food. The results suggest that the caloric and hedonic values of a food may influence food selection across different time courses, and that the effective time horizon for the sequential comparison of foods depends on the specific foods that are compared.

Animals↗
PubMed1989

Learning and meal-associated drinking: meal-related deficits produce adjustments in postprandial drinking.

Two experiments examined the effect of meal-related water deficits on the distribution of meal-associated drinking. In the first procedure free-feeding rats received 10-, 20-, or 30-min delays between the end of a meal and the subsequent availability of postprandial water. Each delay condition remained in effect for 10 consecutive days. The primary effect of the delay was to postpone the intake of postprandial drinking. None of the delay conditions produced an increase in preprandial drinking. However, when the rats were returned to baseline following the delay conditions a pronounced rebound effect was obtained in the proportion of postprandial drinking. The second experiment followed the same general procedure except that 5-min access to water was always presented after each meal and before the postprandial water restrictions. Under this procedure the rats increased their water intake during the 5-min period when the postprandial restrictions were imposed. These findings show that meal-related water deficits can affect the timing and proportion of postprandial drinking, but provide no evidence that meal-related deficits increase preprandial drinking. The results suggest that the anticipation of meal-related water deficits may play a role in shaping the rat's postprandial drinking pattern.

Animals↗
PubMed1988

Anticipatory drinking in rats: compensatory adjustments in the local rate of intake.

The current experiment examined whether dehydrated rats could learn to anticipate disruption of access to water. Previous research showed that rats running in a wheel in order to drink compensated for local disruptions on intake by increasing their rate of intake after, but not prior to the initial disruption. The present experiment exposed rats to either a fixed-ratio (FR) schedule that required rats to run in order to drink or a matched, fixed-time (FT) schedule that allowed the animals intermittent access to water without running. Access to water was disrupted by restricting the quantity of water available per drink bout. Rats increased their local rate of water intake prior to the disruption under the FT schedule but not under the FR schedule. The results suggest that rats can learn to increase their local rate of intake in anticipation of local restrictions on water under response-independent (FT) schedules. It was hypothesized that these anticipatory increases in the local rate of intake resulted from a priming effect due to the motivating effects of stimuli associated with water and/or frustration resulting from attempts to drink prior to water availability.

Animals↗
PubMed1988

Interpellet delay and meal patterns in the rat.

Rats typically eat in short discrete meal periods separated by long intermeal intervals. The present study measured meal patterns and total intake of food and water when the rate of access to food pellets within the meal was reduced by delaying the time between pellet deliveries. In contrast to studies that reduce the caloric density of food, simple interpellet delay produced a marked reduction in meal size at the shorter (32 sec or less) interpellet delays. However, longer delays (up to 128 sec) produced no further change in average meal size. The results suggest that meal size is determined (1) by a positive feedback component with a relatively short decay time probably based on gustatory stimulation from feeding, and (2) by a negative feedback component capable of integrating total intake across delays of up to 1 hour. Increasing the delay between pellets appeared to interfere with the positive feedback component, but not with the negative feedback component.

Animals↗
PubMed1988

Effects of poisoning on predatory and ingestive behavior toward artificial prey in rats (Rattus norvegicus).

Ingestion of novel prey by vertebrate predators that is followed by illness typically decreases the predators' eating the prey more readily than their pursuing or killing it. We used artificial prey-food items (rolling ball bearings that predicted food pellets) to model and extend this finding in laboratory rats. During daily experimental sessions presentations of a novel bearing-food combination were intermixed with presentations of a familiar bearing-food combination. The poisoned animals received lithium chloride injections after each session. Experiment 1a showed that: (a) Poisoning markedly decreased ingestion of the novel food without decreasing the frequency of contact (nose, seize, carry, or chew) with the novel bearing predicting that food. (b) However, poisoning did significantly decrease the average duration of contact with the novel bearing. (c) Poisoning did not decrease behavior toward the familiar food and bearing. Experiment 1b showed that after moderate exposure to pairings of the novel food and bearing, poisoning decreased behavior toward both novel and familiar food and bearings. The results indicate that important aspects of predation can be simulated and examined in the laboratory by using artificial prey-food items. These results also support the conclusions that predatory behavior and ingestion reflect separable modes of behavior and that the presence of novel prey interferes with the generalization of poisoning effects to familiar prey.

Animals↗
PubMed1988

Time horizons in rats: the effect of operant control of access to future food.

The primary goal of this experiment was to determine whether the addition of an operant requirement for access to a less costly (continuous reinforcement) patch of future food increased the time horizon over which that future patch decreased intake in a currently available depleting (progressive-ratio) patch. Three groups of 4 rats were tested. Each member of the earned-time group was required to cumulate a fixed-time outside the progressive-ratio patch to obtain access to food in the less costly patch; the fixed-time requirement ranged from 2 to 64 min. Rats in the matched-time group received response-independent access to less costly food at the average delay shown by the earned-time group. Rats in the matched-time no-food group were removed from the chamber at the same average delay without receiving access to less costly food. Two of the earned-time rats showed an increased time horizon relative to that shown by the matched-time rats (approaching 40 min for 1 rat). The other 2 earned-time rats markedly increased instrumental responding but showed suppression of intake only when food was less than 20 min away. The matched-time group showed less suppression of intake over a similar range of delay intervals. Surprisingly, the matched-time no-food animals also showed suppression of intake concentrated at the end of the session, possibly reflecting the receipt of their entire daily ration 30 min after the session. The potential importance of time horizons to the foraging process is clear, but experimenters are still working out paradigms for investigation of these horizons.

Animals↗