Pavlovian conditioned inhibition.

Examined the notion of conditioned inhibition and suggests a definition in terms of the learned ability of a stimulus to control a response tendency opposed to excitation. 2 techniques of measuring inhibition are outlined: (1) the summation procedure in which an inhibitor reduces the response that would normally be elicited by another stimulus, and (2) the retardation of acquisition procedure in which an inhibitor is retarded in the acquisition of an excitatory CR. Examples of the use of these procedures are given for a variety of UCS modalities. Several possible operations for generating conditioned inhibitors are reviewed: extinction following excitatory conditioning, discriminative conditioning, arrangement of a negative correlation between CS and a UCS, use of an extended CS-UCS interval, and presentation of a stimulus in conjunction with UCS termination. These operations suggest that conditioned inhibitors are not generated either by simple extinction procedures or by pairing a stimulus with UCS termination. By contrast, for both salivary and fear conditioning the other procedures do appear to generate inhibitors. Most of the procedures generating conditioned inhibitors can be described as arranging a negatively correlated CS and UCS. (2 p. ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transfer of negative occasion setting and conditioned inhibition across conditioned and unconditioned stimuli.

The transfer of negative occasion setting and conditioned inhibition across conditioned stimuli (CSs) and unconditioned stimuli (USs) was examined in four experiments that used Pavlovian appetitive feature negative discrimination training procedures with rats. After training with simultaneous compounds (A+, XA–), X inhibited conditioned responding (CRs) elicited by other CSs and CRs supported by other appetitive USs that had not been involved in discrimination training. After training with serial compounds (A+, X→A–), X's power to set the occasion for nonresponding transferred across CSs and USs only if those events had also been involved in serial feature negative discrimination training. The results supported the suggestion that the acquisition of negative occasion setting involves the representation of individual events in a higher order memory system, separate from that involved in simple association, and that negative occasion setters act only on events that are represented in that system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Drug-induced hypothermia and conditioned place aversion.

Examined the relationship between ethanol's thermal and motivational effects in a place conditioning task. In 3 experiments, male albino rats were exposed to a differential conditioning procedure that paired a distinctive tactile stimulus with ethanol (1.2 or 1.8 g/kg) or lithium chloride (3 meq/kg); a different stimulus was paired with saline. Different groups were exposed to ambient temperatures (Ta) of 5°, 21°, or 32°C during each 60-min conditioning trial. Both ethanol and lithium chloride produced hypothermia and conditioned place aversion in rats conditioned at normal Ta. Exposure to high Ta reduced drug-induced hypothermia, increased activity, and decreased conditioned place aversion. Exposure to low Ta did not enhance drug-induced hypothermia or change conditioned place aversion. In general, these findings support the suggestion that the hedonic effects of ethanol and lithium chloride interact with their thermal effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal context and conditioned reinforcement value.

The effectiveness of a stimulus as a conditioned reinforcer depends on the temporal context of reinforcement, that is, the overall rate of reinforcement in the situation. The dominant view has been that context determines the learned value of a stimulus directly, according to delay-reduction theory. By contrast, the contextual choice model (CCM) maintains that value is independent of context and incorporates the effects of context on choice in the framework of the matching law. The authors report 2 experiments with pigeons as subjects that use transfer tests to assess the value of stimuli in the concurrent-chains procedure. Results strongly support the assumption of CCM that pigeons learn the temporal relations between events independently of context but that context modulates the expression of that learning as choice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Uterine position and conditioned taste aversion.

Three experiments investigated the influence of uterine position on the performance of female offspring of female Sprague-Dawley and male Long-Evans rats in a conditioned taste aversion paradigm. 49 females that had males caudal to them in the same uterine horn (MF), 48 females with no caudal males (FF), and 24 males that had occupied a variety of different positions in the uterine horn were examined. Exps I and II confirmed a differential behavioral response by males and females during acquisition and extinction of the conditioned taste aversion. However, no differences were found between MF and FF Ss. In Exp III, in which testosterone was administered to females throughout testing, MF females showed an increased sensitivity to testosterone and a more prolonged rate of extinction than FF females. Exposure to testosterone during prenatal development heightened postnatal responsiveness to testosterone in female Ss. Results are discussed in terms of the organizational and activational effects of testosterone on behavior in a conditioned taste aversion situation. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pavlovian second-order conditioned analgesia.

Three experiments, with 118 Sprague-Dawley rats, assessed conditioned analgesia in a Pavlovian 2nd-order conditioning procedure by using inhibition of responding to thermal stimulation as an index of pain sensitivity. In Exp I, Ss receiving 2nd-order conditioning showed longer response latencies during a test of pain sensitivity in the presence of the 2nd-order conditioned stimulus (CS) than Ss receiving appropriate control procedures. Exp II found that extinction of the 1st-order CS had no effect on established 2nd-order conditioned analgesia. Exp III evaluated the effects of post 2nd-order conditioning pairings of subcutaneous morphine sulfate (10–20 mg/kg) and the shock unconditioned stimulus/stimuli (UCS). Ss receiving paired morphine–shock presentations showed significantly shorter response latencies during a hot-plate test of pain sensitivity in the presence of the 2nd-order CS than did Ss receiving various control procedures; 2nd-order analgesia was attenuated. Data extend the associative account of conditioned analgesia to 2nd-order conditioning situations and are discussed in terms of the mediation of both 1st- and 2nd-order analgesia by an association between the CS and a representation or expectancy of the UCS, which may directly activate endogenous pain inhibition systems. (52 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus relevance in the control of drinking and conditioned fear responses in domestic chicks (Gallus gallus).

Trained groups of young domestic chicks (N = 310) to reject selectively quinine-flavored or electrified water distinguished by 1 of several visual and auditory stimuli. With visual discriminative stimuli, Ss learned within a few trials, but with sounds they learned poorly, although they could hear the sounds. When a compound of flashing light and clicks signaled footshocks for drinking or shock through the water, drinking was completely controlled by the flashing light. In contrast, when the same compound was paired with footshock in a CER paradigm, Ss' behavior was controlled primarily by the clicks. Results constitute a demonstration of stimulus relevance or belongingness, but differ in important ways from other examples of the nonequivalence of stimuli, responses, or reinforcers. (35 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simultaneous backward conditioned inhibition and mediated conditioning.

Demonstrations of retrospective revaluation suggest that remembered stimuli undergo a reduction in association with the unconditioned stimulus (US) present during learning. Conversely, demonstrations of mediated conditioning in flavor-conditioning experiments with rats suggest that remembered stimuli undergo an increase in association with the US present during learning. In a food allergy prediction task with 23 undergraduates, we demonstrated simultaneous backward conditioned inhibition and mediated conditioning effects. These results are compatible with the hypothesis that the direction of change (decrease or increase) in associative strength depends on whether the remembered stimulus was of a different category (conditioned stimulus/antecedent) or the same category (US/outcome) as the presented US. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Representation-mediated overshadowing and potentiation of conditioned aversions.

Examined the ability of CS-evoked representations of flavored substances to modulate the conditioning of LiCl-based aversions to simultaneously presented flavors or odors. In Exps I–III, 156 thirsty Sprague-Dawley rats first received pairings of an auditory CS with a flavored-water UCS; they then received pairings of a compound stimulus with a toxin. Exp IV examined the potentiation of aversion conditioning to a novel odor using 32 Ss. In Exp I, conditioning of a flavor was partially overshadowed when it was presented in compound with a tone that had been previously paired with another flavor. Exp II replicated that result and also found that conditioning to a flavor was not overshadowed when the flavor was presented in compound with a tone that had been paired with that same flavored substance. In Exps III and IV, conditioning to an odor stimulus was potentiated when it was presented in compound with either a tone or another odor that had been previously paired with a flavor stimulus. Results suggest that evoked representations of stimuli may substitute for those events themselves in a variety of associative functions. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interactions between conditioned and unconditioned flavor preferences.

Five experiments investigated how rats' conditioned preferences or aversions for aqueous odors paired with sucrose or salt are affected by their unconditioned response to those tastes. Rats preferred an odor paired with 30% sucrose over an odor paired with 5% sucrose when both were presented in 5% sucrose, but they showed no preference or, if thirsty, showed the reverse preference, when the odors were presented in 30% sucrose. These changes in conditioned preference corresponded to changes in the rats' unconditioned preference for the accompanying sucrose solution. Rats' conditioned aversions for odors paired with salt showed a similar dependence on their reaction to the accompanying salt solution. The results were interpreted as showing that conditioned and unconditioned flavor preferences combine additively, as if mediated by the same sensory representation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Extinction of conditioned flavor preferences.

In a series of 4 experiments, the effects of extinction on flavor preferences conditioned by mixing flavor cues with a nutrient were examined. In each experiment it was observed that rats preferred a flavor cue that had not undergone extinction to one that had. In addition, this preference was reversed in subjects trained thirsty (Experiments 1 and 2) if the associated nutrient had been devalued prior to the test or the preference for the nonextinguished cue was attenuated by nutrient devaluation in subjects trained hungry (Experiments 3 and 4). The results suggest that extinction may weaken associations between the flavor and the specific sensory properties of the nutrient and, for subjects trained hungry, between the flavor and the motivational components of the nutrient as well. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Extinction of Pavlovian conditioned inhibition.

Examined 2 procedures with potential for reducing Pavlovian conditioned inhibition in 4 experiments with 72 male Sprague-Dawley rats. The 1st, simple nonreinforced presentation, was suggested by a theory which has been successful with data from the acquisition of conditioned inhibition. However, nonreinforced presentation of a stimulus, either after conditioned inhibition training or intermixed with such training, failed to produce any loss of the inhibition controlled by that stimulus. The 2nd procedure involved removing the negative correlation between inhibitor and reinforcement. When this correlation was altered, in such a way as to continue UCS presentation, loss of inhibition occurred. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The acquisition of conditioned responding.

This report analyzes the acquisition of conditioned responses in rats trained in a magazine approach paradigm. Following the suggestion by Gallistel, Fairhurst, and Balsam (2004), Weibull functions were fitted to the trial-by-trial response rates of individual rats. These showed that the emergence of responding was often delayed, after which the response rate would increase relatively gradually across trials. The fit of the Weibull function to the behavioral data of each rat was equaled by that of a cumulative exponential function incorporating a response threshold. Thus, the growth in conditioning strength on each trial can be modeled by the derivative of the exponential—a difference term of the form used in many models of associative learning (e.g., Rescorla & Wagner, 1972). Further analyses, comparing the acquisition of responding with a continuously reinforced stimulus (CRf) and a partially reinforced stimulus (PRf), provided further evidence in support of the difference term. In conclusion, the results are consistent with conventional models that describe learning as the growth of associative strength, incremented on each trial by an error-correction process. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Poisoning and overdose

The differential diagnosis of all patients with altered mental status must include drug toxicity. In particular, intentional or unintentional overdosing and/or poisoning are common emergency department presenting complaints. A comprehensive approach to managing these patients must incorporate aggressive information gathering, a careful physical examination looking for toxic syndromes, and diagnostic testing. Proper decontamination is the key to effective management, as is the use of specific antidotes when indicated.     

Action identification of drinking and self-control.

A number of investigators have proposed that self-control over addictive behaviors may be influenced by the way individuals mentally represent their actions. Previous research based on questionnaires has suggested that those who report higher-level identifications of their alcohol use behavior may exhibit more difficulty controlling their alcohol use (Wegner, Vallacher, & Dizadji, 1989). However, it is unclear whether this association is because of characteristic ways of mentally representing specific drinking events or the fact that those who have more impaired control consume more alcohol and drink across a broader array of situations. The current study sought to address this question by examining the association between impaired control over alcohol and action identification of drinking behavior in a structured laboratory drinking task. Ninety-one young adult hazardous drinkers (21–35 years) completed the Impaired Control Over Alcohol Scale (Heather, Tebbut, Mattick, & Zamir, 1993) and an alcohol consumption task. Participants then completed a Likert scale measure to assess action identification of their drinking behavior. Results showed that those who reported greater impaired control over alcohol experienced the drinking task at higher-level action identification even when accounting for alcohol consumption variables. These findings are consistent with the view that higher-level identification of alcohol use behavior may hinder self-control (Wegner et al., 1989), and that self-management approaches may be enhanced through strategies to address mental representation of action. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intertrial interval effects in classically conditioned fear to a discrete conditioned stimulus and to situational cues.

In Exp I fear was classically conditioned in a total of 240 female hooded and Sprague-Dawley rats with a discrete conditioned stimulus (CS) at intertrial intervals (ITIs) of 15, 45, 75, 105, 165, or 225 sec and in Exp II, with an additional 144 Ss, with or without a discrete CS at ITIs of 165, 225, or 285 sec. The amount of fear conditioned to situational cues and to the discrete CS plus situational cues was then measured by the learning of a hurdle-jumping response which allowed escape from the fear-eliciting stimuli. Results suggest that as ITI was lengthened fear conditioned to situational cues alone and to the discrete CS increased. However, following conditioning with a discrete CS, fear elicited by situational cues increased with ITI but then decreased, presumably because a discrimination had been formed between the situational cues and the compound of CS plus situational cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Models of parenting and adolescent drinking.

Comments on the A. W. Collins et al article (see record 2000-13816-002) which discusses behavioral genetics and the parenting theory. The current author points out that Collins et al made little mention of the influence of parenting on adolescent drinking behavior. Selected studies on this topic are reviewed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pro-Leu-Gly-NH? serves as a conditioned stimulus in the acquisition of conditioned tolerance.

The effect of Pro-Leu-Gly-NH? (MIF) on the acquisition of tolerance to morphine-induced antinociception and its efficacy as a cue predictive of morphine administration was examined. Daily administration of MIF prior to morphine injection did not attenuate the acquisition of tolerance to the antinociceptive properties of morphine, as measured by the latency to hindpaw lick in a hot-plate test of analgesia. When the animals were tested 72 hrs later without MIF pretreatment, they appeared to lose tolerance, as indicated by longer latencies to paw lick. These data suggest that in some situations MIF may interfere with the acquisition of tolerance by acting as a cue that reliably predicts the antinociceptive properties of morphine. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of drinking history on food-deprived drinking in the rat.

Investigated the role of drinking during development in 40 male hooded Long-Evans rats. Experimental Ss were deprived of water during rearing; ingestion of lettuce provided for sufficient fluids. Body weight, feeding, drinking, and urine volume over successive food deprivation periods were compared with normally reared controls. The lettuce-reared Ss drank less water and ate less lettuce when food deprived, but did not differ from normal Ss in drinking or in lettuce intake when food was available ad lib. It is suggested that lettuce-reared animals drink water principally in response to fluid deficits. Other research indicates that the drinking of normally reared rats anticipates fluid deficits and is not initiated by events related to the need for water. The present results suggest that this anticipatory drinking is acquired. (PsycINFO Database Record (c) 2010 APA, all rights reserved)