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PubMed1988

Effects of early postnatal gonadal steroids on acquisition and extinction of a single alternation response in discrete-trials lever pressing.

The present report studies the effect of sex on the acquisition and extinction of a single alternation schedule of reinforced (R) and nonreinforced (N) trials in a Skinner box. In addition to the investigation of the basic sex differences in Experiment 1, the effects of early gonadal steroids treatment and postpubertal gonadectomy of male and female rats were examined in Experiments 2 and 3, respectively. Both acquisition and extinction performances were evaluated by means of latency. In Experiment 1, males showed higher latencies on N trials and extinguished faster than female rats. In Experiment 2, female androgenization and male orchidectomy on day one after birth reversed the direction of the sex differences found in the previous experiment. However, postpubertal gonadectomy (Experiment 3) does not affect the performance of male and female rats.

Animals↗
PubMed1993

Forced extinction as a means to evaluate consolidation gradient of a passive avoidance response in the rat.

Passive avoidance response (PAR) consolidation gradient, and US (footshock) intensity/engram strength relationship were investigated by means of specific forced extinction procedure (30 min detention in the shock box without receiving punishment) in Wistar rats trained in the light-dark box apparatus. Different groups of rats (punished either with 0.8 or 1.2 mA footshock intensity) underwent detention at different postacquisition time delays: immediately or 1, 2, 4 days after acquisition training. By means of this purely behavioral paradigm, designed to investigate a specific PAR memory trace, previous results obtained by using diverse and sometimes unspecific memory-disrupting agents were fully confirmed: PAR strength and consolidation gradient are positively related to US intensity. The influence of differential generalization effects on extinction is discussed. An unexpected finding was that from engrams that are experimentally shown to be of unequal resistance to disruption, equal conditioned responses are obtained.

Animals↗
PubMed1977

Effect of chlordiazepoxide on the partial reinforcement extinction effect.

Rats were trained to run in a straight alley under conditions of partial or continuous reinforcement. Extinction was slower after partial reinforcement. Chlordiazepoxide, administered during acquisition only, had no effect on acquisition but abolished the partial reinforcement extinction effect. The results support the hypothesis that chlordiazepoxide acts by attenuating the effects of averisive stimuli.

Animals↗
PubMed1977

Behavioural basis of the dorsal bundle extinction effect.

Lesion to the fibres of the dorsal noradrenergic bundle arising from the locus coeruleus using the selective neurotoxin 6-hydroxydopamine has been shown to produce a resistance to extinction on a number of behavioural tests without affecting the acquisition learning process itself. The experiments reported here are aimed at elucidating the behavioural mechanisms involved in this resistance to extinction. Theories invoking general hyperactivity, internal inhibition and perseveration are tested in the following experiments and all are shown to be contrary to the observed facts. On the basis of other data it is tentatively concluded that the dorsal noradrenergic bundle may play a role in the filtering out of irrelevant stimuli or in the memory of non-reward.

Animals↗
PubMed1979

Interaction of brain noradrenaline and the pituitary-adrenal axis in learning and extinction.

The effect of 6-hydroxydopamine-induced degeneration of the dorsal tegmental noradrenergic (NA) projection alone or in combination with the removal of the adrenal glands was examined on several behavioral tasks. No impairment of acquisition on a continuously reinforced lever pressing response for food reward was seen as a result of the combined treatment. However, resistance to extinction was observed after depletion of forebrain noradrenaline on its own and this effect was prevented by the adrenalectomy. Adrenalectomy on its own failed to affect extinction. Acquisition of a passive avoidance task was slightly impaired after forebrain noradrenaline depletion but only the group with combined noradrenaline loss and adrenalectomy showed a 24 hour retention deficit. No alteration in shock thresholds was found in any group although both adrenalectomized groups consumed less food and were slightly less active in locomotor cages. It is suggested that previous reports of acquisition and retention deficits in avoidance tasks after combined dorsal NA bundle lesions and adrenalectomy are due to alterations in fear motivation rather than to a general learning impairment.

Animals↗
PubMed1980

Effects of diazepam on extinction induced aggression in pigs.

Pigs were trained to press a panel with their snout to get food in an operant conditioning chamber. Aggressive behaviour which developed between two pigs submitted together to extinction was used as a baseline to study the effects of 1-2 mg/kg diazepam. When access to the response panel and feeding area was permitted, diazepam enhanced resistance to extinction and did not modify aggression. When access to the response panel and feeding area was not permitted, diazepam increased the severity of aggression observed between the animals. In both instances, plasma corticosteroid levels were depressed in diazepam-treated pigs. These results suggest that benzodiazepines do not act on frustation or aggressiveness per se, but rather strengthen the prevailing behavioural attitudes in the animals' repertoire at the time of test.

Adrenal Cortex Hormones↗
PubMed1982

Effects of TRH on acquisition and extinction of shuttlebox-avoidance behavior in Fischer344 rats.

Thyrotropin-releasing hormone (TRH) was injected intraperitoneally into male Fischer344 rats in doses ranging between 1 mg/kg and 20 mg/kg to assess the effects on the acquisition and extinction of shuttlebox-avoidance behavior. Administration of 20 mg/kg TRH resulted in a rapid acquisition of avoidance behavior in early training trials. This enhancement did not involve changes in the occurrence of anticipatory responses to an inevitable shock but was correlated with an increase of concurrent intertrial-responses. Thus, the behavioral changes observed would be a reflection of TRH-induced changes on motor activity. TRH treatment did not alter the resistance to extinction of the avoidance response. This finding is corroborated by the fact that rats given the TRH treatment withheld the well-learned response to a warning signal, when this response was selectively punished after initial acquisition stage.

Animals↗
PubMed1987

Diazepam self-administration and resistance to extinction.

Self-administration behavior was maintained by a unit dose of 0.03 mg/kg diazepam in 4 of 5 monkeys trained to respond on a lever by successive approximation using diazepam or saline. A dose-response function was determined using diazepam doses ranging between 0.01 and 0.3 mg/kg/infusion. Peak rates of responding occurred at doses of 0.01 or 0.03 mg/kg/infusion and drug intake was directly related to dose. When saline was substituted for diazepam either before or again after the dose-response function was determined, levels of responding remained unexpectedly high, even after as many as 16 consecutive sessions. The rates of responding maintained under extinction conditions appeared to be directly related to the amount of diazepam previously self-administered. For instance, monkeys which did not initially have high rates of responding for saline showed increases in responding after additional exposure to diazepam. Furthermore, the one monkey with low diazepam self-administration rates also had low rates of responding for saline. However, following a period of cocaine self-administration, responding declined in all monkeys when saline was substituted for cocaine. The data suggest that diazepam self-administration affects responding under extinction conditions, an effect which makes the interpretation of diazepam's reinforcing properties difficult.

Animals↗
PubMed1987

The abolition of the partial reinforcement extinction effect (PREE) by amphetamine: disruption of control by nonreinforcement.

Two groups of rats were trained to run in a straight alley. The continuously reinforced (CRF) group received a food reward on every trial. The partially reinforced (PRF) group was rewarded on a quasi-random 50% schedule. d-Amphetamine 1 mg/kg was administered to PRF animals in acquisition in a 2 X 2 design, i.e., drug-no drug on reinforced trials and drug-no drug on nonreinforced trials. In four CRF groups, the drug was administered in the same sequence as in the PRF groups. Following acquisition, all animals were given 4 days of CRF retraining and tested in extinction. No drug was given in retraining and extinction. The PREE, i.e., increased resistance exhibited by PRF animals as compared to CRF animals, was obtained in groups which received placebo on all acquisition trials or amphetamine on rewarded trials and placebo on nonrewarded trials. The PREE was abolished when amphetamine was administered throughout the acquisition trials or on nonrewarded trials, irrespective of drug treatment on rewarded trials.

Animals↗
PubMed1989

The effects of amphetamine on a multitrial partial reinforcement extinction effect (PREE) in an operant chamber.

Two experiments investigated the effects of d-amphetamine (1 mg/kg) on the partial reinforcement extinction effect (PREE) in an operant chamber using a discrete multitrial procedure. Experiment 1 used a random 50% partial reinforcement (PRF) schedule. Experiment 2 used two 40% PRF schedules: one schedule maximized the number of nonreinforced trials preceding any given reinforced trial (maximum N-length of four) and the second maximized the number of N-R transitions (N-length of one). In both experiments, the continuously reinforced (CRF) animals received a reward on every trial. The PREE, i.e., increased resistance to extinction of PRF as compared to CRF animals, was obtained in the random 50% PRF and the schedule maximizing N-length in both the placebo and amphetamine-treated animals. Both drug and no-drug animals failed to exhibit PREE on the schedule maximizing N-R transitions. These results show that on a PRF schedule with short intertrial intervals, amphetamine-treated animals are not impaired in their capacity to learn sequences of events and to associate the outcomes of preceding trials with subsequent consequences.

Amphetamine↗
PubMed1995

The effects of nucleus accumbens dopamine depletions on continuously reinforced operant responding: contrasts with the effects of extinction.

Two experiments were undertaken to study the role of nucleus accumbens dopamine (DA) in instrumental lever pressing on a continuous reinforcement schedule (CRF). In the first experiment, the neurotoxic agent 6-hydroxydopamine was infused directly into the nucleus accumbens to investigate the effects of DA depletion on lever pressing performance. DA depletion had only a modest effect on the total number of lever presses, and there was a significant effect on total lever presses only on the first test day (third day postsurgery). Analyses also were performed on responding across the 45-min session by breaking down the session into three 15-min periods. During the test session on day 3 postsurgery, there was a significant group x time interaction, with DA-depleted rats showing a significant reduction in the numbers of responses in the first 15-min period, but no significant effects over the second or third 15-min period within the session. Although control rats showed a within-session decline in responding, the DA-depleted rats did not. In addition, analysis of interresponse times (IRTs) indicated that accumbens DA depletions produced a slowing of the local rate of responding as indicated by a significant decrease in high rate (i.e., short-duration IRT) responses and an increase in low rate (i.e., long-duration IRT) responses. In a second experiment, the effects of extinction on CRF performance were investigated. Unlike the effects of nucleus accumbens DA depletion, extinction produced lower levels of responding throughout the entire test session.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1979

Theories of the dorsal bundle extinction effect.

Selective destruction of the noradrenaline systems in the rat brain using the neurotoxin 6-hydroxydopamine has been found to cause resistance to extinction in a number of behavioural situations. Several theories concerning the behavioural mechanism altered by the lesion, and hence about the role of noradrenaline in normal brain functioning, are proposed and evaluated. Theories suggesting a role for noradrenaline in activity, perseveration, internal inhibition, frustrative non-reward, motivation, or secondary reinforcement, fail to explain all the available evidence and direct tests of each theory fails to support its predictions. A model which suggests that noreadrenaline is involved in attentional behaviour, specifically in filtering out or learning to ignore irrelevant environmental stimuli, is successful in explaining all available data and direct tests of the lesioned rats' attentional capacity serve to confirm many of the predictions of an attentional theory of the dorsal bundle extinction effect.

Animals↗
PubMed1982

Acquisition and extinction of continuously and partially reinforced running in rats with lesions of the dorsal noradrenergic bundle.

Local injection of 6-hydroxydopamine was used to selectively destroy the dorsal ascending noradrenergic bundle (DB) in rats. Two lesion procedures were used, differing in the extent of depletion of forebrain noradrenaline they produced (greater than 90% or 77%). In Experiments 1-3 the rats were run in a straight alley for food reward on continuous (CR) or partial (PR) reinforcement schedules. The smaller lesion reduced and the larger lesion eliminated the partial reinforcement acquisition effect (i.e. the faster start and run speeds produced by PR during training) and the partial reinforcement extinction effect (PREE, i.e. the greater resistance to extinction produced by PR training); these changes were due to altered performance only in the PR condition. Abolition of the PREE by the larger DB lesion occurred with 50 acquisition trials, but with 100 trials the lesion had no effect. In Experiment 4 rats were run in a double runway with food reward on CR in the second goal box, and on CR, PR or without reinforcement in the first. The larger lesion again eliminated the PREE in the first runway, but did not block the frustration effect in the second runway (i.e. the faster speeds observed in the PR condition after non-reward than after reward in the first goal box). These results are consistent with the hypothesis that DB lesions alter behavioural responses to signals of non-reward, but not to non-reward itself. They cannot be predicted from two other hypotheses: that the DB mediates responses to reward or that it subserves selective attention. Since septal and hippocampal, but not amygdalar, lesions have been reported to produced similar behavioural changes, it is proposed that the critical DB projection for the effects observed in these experiments is to the septo-hippocampal system.

Animals↗
PubMed1983

An experimental study of covert extinction on smoking cessation.

Twenty-one subjects participated on a volunteer nonpaid basis in a smoking cessation treatment experiment. The subjects were randomly assigned to three groups: one receiving training in covert extinction, one in relaxation, and a waiting list group serving as a control group. Behavioral (number of cigarettes smoked), physiological (pulse rate during treatment sessions) and cognitive (craving for cigarettes) assessments were made during and between sessions. Analysis of variance showed the time variable to be significant for number of cigarettes. Tukey's HSD tests showed a significant decrease in smoking after treatment for all three groups, and also for the two treatment groups until the follow-up occasion, although smoking had returned to a higher level (though not the initial one) after one month. There were also significant differences between the control group and both treatment groups with regards to pulse rate changes in treatment sessions. There was no significant change in craving, although a tendency pointed in the same direction for pulse rates. A tentative conclusion is that covert extinction is not a specific effective treatment method surpassing other nonspecific treatment procedures.

Adult↗
PubMed2006

Acquisition, extinction and temporal discrimination in human conditioned avoidance.

Two experiments were conducted with the aim of designing a videogame for the study of human conditioned avoidance. Participants had to destroy enemy spaceships with the goal of increasing the score in a counter. Coloured signals might announce the launching of a bomb that could hit participant's spaceship producing a 30 points decrease in participant's score. Three groups of participants were trained in discriminating between a warning signal (W) and a safety signal (S) in Experiment 1. Instrumental group could avoid the loss of points by hiding the spaceship before the offset of W. Participants in the Yoked group received the same treatment received by their instrumental partners, regardless of their behaviour. In the Pavlovian group, W was always followed by the loss of points, regardless of participant's behaviour. Discrimination between W and S was better in the Instrumental groups than in the Yoked and Pavlovian control groups. Experiment 2 found extinction of avoidance when the warning signal was not followed by the bomb. Temporal discrimination was found within the participants that received the instrumental contingency in both experiments, with higher avoidance response towards the end of the warning signal. Temporal discrimination disappeared after extinction in Experiment 2.

Adult↗
PubMed2006

Effect of US identity on elimination and recovery of autoshaped responding with explicitly unpaired and degraded contingency extinction procedures.

The depressive effects of noncontingent and explicitly unpaired food unconditioned stimuli (USs) and the recovery from those effects on autoshaped responding were examined in a series of experiments with pigeons. In Experiments 1 and 2, responding to a keylight conditioned stimulus (CS) previously paired with food was depressed equally by explicitly unpaired presentations of either that same food or a different food. Furthermore, responding recovered equally following removal of the explicitly unpaired foods. In contrast, Experiments 3 and 4 showed that noncontingent presentations of a food US depressed responding more to a keylight CS paired with that same food than to a keylight CS paired with a different food. Moreover, removal of the noncontingent foods led to complete recovery but more rapid extinction of responding to the same keylight relative to the different keylight. The implications of these results for understanding the mechanisms underlying depression and recovery of responding following degraded contingency and explicitly unpaired extinction procedures are discussed.

Animals↗
PubMed2005

A role for prefrontal cortex in the extinction of a conditioned taste aversion.

This study used immunohistochemical methods to determine if the medial prefrontal cortex (mPFC) is involved in the extinction of a conditioned taste aversion (CTA). As rats reached 90% reacceptance of a tastant (saccharin: SAC) that had previously been associated with lithium chloride-induced malaise, c-Fos protein expression increased dramatically as compared to animals with active CTAs, animals without CTAs (i.e., explicitly unpaired CS-US exposures) or animals drinking SAC for the first time. These data indicate a role for mPFC (prelimbic and infralimbic cortex) in the formation of a CTA extinction memory.

Animals↗
PubMed2006

A model describing the effect of sex-reversed YY fish in an established wild population: The use of a Trojan Y chromosome to cause extinction of an introduced exotic species.

A novel means of inducing extinction of an exotic fish population is proposed using a genetic approach to shift the ratio of male to females within a population. In the proposed strategy, sex-reversed fish containing two Y chromosomes are introduced into a normal fish population. These YY fish result in the production of a disproportionate number of male fish in subsequent generations. Mathematical modeling of the system following introduction of YY fish at a constant rate reveals that female fish decline in numbers over time, leading to eventual extinction of the population.

Animals↗