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PubMedDate not supplied

Effects of partial reinforcement on conditioning, conditional probabilities, asymptotic performance, and extinction of the rabbit's nictitating membrane response.

Classical conditioning and extinction of the rabbit nictitating membrane response was investigated under 100 per cent, and two 50 per cent reinforcement conditions (50% equated total trials, and 50% equated reinforced trials) at average intertrial intervals (ITIs) of 30 and 60 sec. It was found that: (1) partial reinforcement reduced the rate of conditioning, but all groups eventually attained asymptomatic performance levels near 100 per cent; (2) first-order and second-order conditional probabilities following reinforced and nonreinforced trials were virtually identical; and (3) no partial reinforcement extinction effect (PREE) was observed.

Acoustic Stimulation↗

PubMed1995

Evaluative conditioning is a qualitatively distinct form of classical conditioning: a reply to Davey (1994).

Based on a critical review of the literature, Davey (1994) [Behaviour Research and Therapy, 32, 291-299] concludes that there is no sufficient evidence to support the theoretical position that evaluative conditioning is a qualitatively different form of classical conditioning. In the present manuscript, we will try to show that Davey's conclusion is biased by: (a) an overemphasis on what he believes to be problematic procedural aspects of previous evaluative conditioning studies; and (b) a selective reading of the available evidence. Finally, an attempt is made to characterize evaluative conditioning phenomena as the output of a Referential Learning System, which can be distinguished from an Expectancy Learning System.

Association Learning↗

PubMed1987

Initial localization of the acoustic conditioned stimulus projection system to the cerebellum essential for classical eyelid conditioning.

Previous experiments have demonstrated a sufficient and necessary involvement of mossy fibers in projecting conditioned stimulus information to the cerebellum during classical eyelid conditioning in rabbits. Presented here are electrophysiological, anatomical, and lesion data that suggest that cells within the lateral pontine nuclear region may be essentially involved in projecting information concerning the occurrence of acoustic conditioned stimuli to the cerebellum during classical conditioning.

Acoustic Stimulation↗

PubMed1991

Modulation of a discrete Pavlovian conditioned reflex by a putative emotive Pavlovian conditioned stimulus.

Three experiments showed the modulation of a rabbit eyeblink conditioned response (CR) to a Pavlovian conditioned stimulus (CS) by 30-s stimuli (A & B) that had been differentially paired with paraorbital shock. The CS (Y) was a 1,050-ms cue that had been paired with paraorbital shock outside A or B. In testing, the amplitude of CRs was greater when Y was presented within A than within B. Differential modulation occurred whether shock in A had been preceded by another 1,050-ms cue, X(AX+,BX-;Experiment 1) or not (A+B-;Experiment 2). Experiment 3 compared the technique of Experiment 1 (AX+) with that of Experiment 2 (A+) and found the latter to be advantageous for facilitation of CRs to Y by A. These data are consistent with the predictions of a model of Pavlovian conditioning (AESOP, Wagner & Brandon, 1989) that distinguishes between emotive and sensory conditioning as did Konorski (1967).

Animals↗

PubMed1991

Modulation of a conditioned eyeblink response by a putative emotive stimulus conditioned with hindleg shock.

Two experiments with rabbits showed that the differential modulation of a conditioned eyeblink response (CR) by 30-s auditory stimuli previously paired with shock was independent of the locus of shock application. In Experiment 1, the modulation occurred when the CR was trained with paraorbital shock and the 30-s stimuli were trained with either hindleg or paraorbital shock. Experiment 2 replicated the observed adequacy of hindleg shock for modulation training, under 2 different conditions of eyeblink conditioning. The data, along with the findings that the same 30-s stimuli similarly facilitate the unconditioned eyeblink and the airpuff-elicited startle response (Brandon, Bombace, Falls & Wagner, 1991), were viewed as supporting the notion that the CR-modulation is dependent upon a conditioned fear response elicited by the 30-s cues (Wagner & Brandon, 1989).

Animals↗

PubMed1982

Appetitive conditioning in neonatal rats: conditioned orientation to a novel odor.

These experiments document a form of early appetitive learning in rats obtained using classical conditioning procedures. Some of the special determinants of this conditioning are described, as well as ontogenetic changes in the effectiveness of training procedures. Learning was apparent when deprived 3- and 6-day old rats oriented to and maintained contact with a novel and normally aversive odor after this odor had been paired with oral infusions of milk (Experiment I). The effectiveness of the conditioning procedures depended on the temperature at which pups were trained (Experiment IB). Moreover, the reinforcing properties of milk infusions depended on deprivation (Experiment IC). This conditioned change in responsiveness to odor was specific to the odor that had been paired with milk (Experiment II) and was retained for at least 24 hr (Experiment III).

Age Factors↗

PubMed1989

Ontogeny of conditioned inhibition of conditioned respiratory suppression in kittens.

Excitatory and inhibitory classical conditioning were examined in 4-week-old, 8-week-old, and 12-week-old kittens. Conditioned respiratory suppression (CRS) was a measure of conditioned fear. The inhibitory conditioning procedure was designed to model the schedule of events that normally accompanies successful coping behavior: The safety signal predicted the cancellation of shock that would otherwise follow the danger signal, rather than simply the absence of shock. Before training, the stimuli elicited small unconditioned respiratory suppression in the 4-week-old and 8-week-old kittens, but not in the juvenile, 12-week-old kittens. During training, danger signals came to elicit robust CRS after 3-4 sessions (20-30 trials) in every age group. Acquisition of inhibition of CRS was also observed within 2-3 days (20-30 trials). The effectiveness of inhibitory stimuli improved significantly with age. The safety signal also inhibited fear (CRS) elicited by a second danger signal. Thus, the kittens learned inhibition to the safety signal per se, rather than having learned to discriminate some nonreinforced configured cue from the danger signal presented alone.

Age Factors↗

PubMed2005

A five-minute, but not a fifteen-minute, conditioning trial duration induces conditioned place preference for cocaine administration into the olfactory tubercle.

The establishment of conditioned place preference (CPP) with intracranial injections requires specific injection sites, drug doses, and conditioning trial durations. We examined the role of conditioning trial duration in CPP with cocaine injections into the medial olfactory tubercle. Only those rats that had spent 5 min in the compartments showed CPP for cocaine, while rats that had been removed immediately or spent 15 min following cocaine injections did not show CPP. Effective conditioning trial durations for CPP induced by intracranial cocaine injections are apparently much shorter than those typically used for intracranial injections of other drugs of abuse.

Animals↗

PubMed1992

Blockade of conditioned taste aversion by scopolamine and N-methyl scopolamine: associative conditioning, not amnesia.

The anticholinergic, scopolamine, consistently disrupts one-trial passive avoidance conditioning but the effects of such drugs on one-trial conditioned taste aversion (CTA) are variable and contradictory. In the present study, treatment of rats with scopolamine impaired the suppression of sucrose intake by post-ingestion administration of lithium chloride (LiCl) in a two-bottle choice test. A similar effect was obtained by using N-methyl scopolamine which penetrates the brain only to a limited degree on acute administration. The blockade of CTA could be prevented in three ways: (i) by exposing the rats to sucrose only on the training day, (ii) by pre-exposing the rats to both sucrose and scopolamine, and (iii) by using a less palatable sucrose/ascorbate mixture. The results demonstrate that the effect of scopolamine on taste aversion is not mediated by the central nervous system, and can be modified by altering the novelty and relative salience of the taste conditioned stimulus. These experiments suggest that conditioned associations between taste and LiCl, and scopolamine and LiCl may underlie the blockade of CTA by scopolamine.

Amnesia↗

PubMed2003

Reduced ethanol-induced conditioned taste aversion and conditioned place preference in GIRK2 null mutant mice.

RATIONALE: Previous studies have shown that GIRK2 channel function is enhanced by ethanol and that GIRK2 null mutant mice are less sensitive to some of ethanol's effects, including anxiolysis, habituated locomotor stimulation, and acute handling-induced convulsions than wild types. Under some conditions, GIRK2 knockout mice consume more ethanol than wild types, but it is unclear whether they do so because they are more sensitive to ethanol's rewarding effects or less sensitive to its aversive effects. OBJECTIVE: To further assess the role of GIRK2 in ethanol action, GIRK2 null mutant and wild type mice were tested in conditioning models that measure the motivational effects of ethanol. METHOD: In a conditioned taste aversion (CTA) procedure, knockout and wild type mice were given ethanol (0.0, 2.0, 2.5, or 3.5 g/kg, IP) following 1-h access to saccharin every 48 h over a 10 day period. In a conditioned place preference (CPP) procedure, knockout and wild type mice were given ethanol (2.0 or 3.0 g/kg, IP) paired with one stimulus (grid or hole floor) and saline paired with the other. After four 5-min trials with each stimulus, a 60-min choice test was done. RESULTS: The results demonstrated a genotypic difference in both paradigms. In CTA, there was no difference between genotypes at 0.0 or 3.5 g/kg ethanol, but at the 2.0 and 2.5 g/kg doses, wild types developed a stronger aversion to saccharin than knockouts. In CPP, wild types developed place preference, but knockouts did not. CONCLUSIONS: These studies show that GIRK2 deletion reduced ethanol's impact in tasks that are commonly used to index the drug's rewarding and aversive effects. These findings could reflect either a learning/memory deficit or decreased sensitivity to ethanol's motivational effects in null mutant mice. The latter interpretation is more consistent with previous data showing that knockout mice consume higher doses of ethanol than wild type mice.

Animals↗

PubMed1997

Symmetrical effects of amphetamine and alpha-flupenthixol on conditioned punishment and conditioned reinforcement: contrasts with midazolam.

In a test of conditioned punishment, saline-treated controls showed a moderate bias in responding away from a lever producing a response-contingent auditory conditioned stimulus (CS) that had been paired with mild footshock during training and towards a lever producing a neutral auditory CS. Systemic treatment with the indirect dopamine (DA) agonist amphetamine (0.25-1.0 mg/kg) produced a dose-dependent increase in the punishing effect of the aversive CS, whilst responding on the neutral CS lever was unchanged. Treatment with the dopamine-receptor antagonist alpha-flupenthixol (0.125, 0.25 mg/kg) decreased the efficacy of the punishing CS, but again left responding on the neutral lever unchanged. The benzodiazepine midazolam (0.1, 0.3 mg/kg) had a similar effect to alpha-flupenthixol, but treated animals showed a preference for the aversive CS. Parallel results were observed with amphetamine (0.25 mg/kg) and alpha-flupenthixol (0.125, 0.25 mg/kg) in a matched test of positive conditioned reinforcement, with amphetamine enhancing, and alpha-flupenthixol reducing, the efficacy of the CS paired with food. Midazolam treatment (0.1-1.0 mg/kg) had no effect on the reinforcing impact of an appetitive CS. Thus dopaminergic agents modulate the behavioural impact of both appetitively and aversively motivated conditioned stimuli on instrumental performance, whilst the benzodiazepine midazolam has a selective impact on aversively-motivated stimuli that is qualitatively distinct from that of the dopaminergic antagonist alpha-flupenthixol.

Amphetamine↗

PubMed1990

Stimulant-conditioned locomotion is not affected by blockade of D1 and/or D2 dopamine receptors during conditioning.

A series of experiments were conducted to investigate the role of dopamine (DA) D1 and D2 receptor subtypes in stimulant-conditioned locomotion in rats. Expt. 1 demonstrated that locomotion could be induced by a testing situation when that situation was previously paired with (+)-amphetamine (1.5 mg/kg, s.c.) or a D2 receptor selective agonist (PHNO, 15 or 30 micrograms/kg, s.c.), but not when the drug treatments were given 3 h after exposure to the situation. The selective D2 receptor antagonist, haloperidol (50 micrograms/kg, i.p.), and the D1 receptor antagonist, SCH 23390 (20 micrograms/kg, s.c.), blocked amphetamine-induced locomotion during the pairing process, but failed to block amphetamine-conditioned locomotion as assessed during a drug-free test in Expt. 2. This was true when the antagonists were given separately or together. The results of Expts. 3 and 4 showed that doses of the D1 (20 micrograms/kg, s.c.) and D2 antagonist (250 micrograms/kg, i.p.) that blocked the unconditioned locomotor effects of PHNO failed to block its conditioned locomotion. It is concluded that neither D1 nor D2 DA receptors are essential for the development of stimulant-conditioned locomotion.

Amphetamines↗

PubMed1991

Haloperidol impairs classical nictitating membrane conditioning in rabbits when stimulation of the pontine nuclei is used as a conditioned stimulus.

Rabbits classically conditioned with stimulation of the pontine nuclei as a conditioned stimulus (CS) and a corneal air puff as an unconditioned stimulus (US) were injected with haloperidol (250 micrograms/kg). Three different stimulation CS intensity levels were used. Haloperidol administration significantly decreased the number of conditioned responses during training at all CS intensity levels with the greatest impairment seen when medium and low levels of stimulation were delivered as a CS. These results provide evidence that haloperidol disrupts classical conditioning through actions at central brain sites (i.e., sites at or efferent to the point of stimulation) and not in pathways normally involved in projecting peripheral CSs to more central locations.

Animals↗

PubMed1988

Behavioral and neural correlates of postnatal olfactory conditioning: I. Effect of respiration on conditioned neural responses.

Following olfactory classical conditioning, infant rats exhibit a preference for the conditioned odor and exhibit enhanced uptake of focal 14C 2-deoxyglucose (2-DG) within the olfactory bulb. The present experiments assessed the role of respiration on the expression of the enhanced 2-DG uptake response. Pups were conditioned from postnatal day (PN) 1-18 with an olfactory stimulus paired with a reinforcing tactile stimulus which mimics maternal contact (Odor-Stroke). Control pups received odor only or tactile stimulation only. On PN 19, pups received 1 of 3 tests: 1) a two-odor choice test, 2) an odor/2-DG test with normal respiration allowed, or 3) an odor/2-DG test with respiration experimentally controlled. The results indicated that: 1) Odor-Stroke pups learned the conditioned odor preference, 2) Odor-Stroke, normally respiring pups exhibited enhanced olfactory bulb 2-DG uptake when compared to control pups. No difference in respiration rate was detected between groups in normally respiring pups. 3) Odor Stroke pups whose breathing was experimentally controlled exhibited enhanced olfactory bulb 2-DG uptake when compared to control pups with an identical number of respirations. Together, these results demonstrate that modified respiration during testing is not required for the expression of a modified olfactory bulb response to learned attractive odors. Therefore, the data suggest that the olfactory system itself is modified by early learning.

Animals↗

PubMed1986

Conditional shifts in thermic responses to sequentially paired drugs and the "conditional hyperactivity" hypothesis.

Previous experiments have demonstrated that upward shifts in a rat's thermic response to certain drugs may be observed when these drugs have been paired on several occasions with agents that induce hypothermia. A "conditional hyperactivity" hypothesis suggests that these upward shifts may simply reflect drug elicited increases in body movements which translate into higher temperatures. The present experiment explored this hypothesis. Atropine sulfate (10 mg/kg) was paired with sodium pentobarbital (40 mg/kg) on multiple occasions and several tests were conducted with both drugs. This treatment yielded a conditional hyperthermic response to atropine, but the drug was not found to elicit an increase in gross motor movements. Of greatest interest was the finding that the atropine, when injected 30 min prior to a hypnotic dose of pentobarbital (80 mg/kg), attenuated the hypothermia normally induced by this barbiturate while leaving the duration of hypnosis unaffected. This upward thermic shift cannot be accounted for by the "conditional hyperactivity" hypothesis because the animals were immobile while under pentobarbital's influence. These findings suggest that autonomic events, as yet unspecified, may underlie certain conditional temperature increases.

Animals↗

PubMed1988

A new conditioning paradigm: conditioned limb movements in locomoting decerebrate ferrets.

These experiments address the hypothesis that the trajectory of a forelimb in decerebrate ambulating ferrets can be conditioned to avoid an obstacle encountered during the locomotor cycle. The perturbation was produced by interjecting a bar into the trajectory of the forelimb during swing phase. Over 5-15 steps the flexion of the elbow progressively increased until the forelimb was elevated over the bar. Avoiding the bar often required that the maximum height of the paw during swing phase was doubled. When the bar was no longer thrust into the trajectory of the forelimb, the conditioned behavior persisted for several step cycles. The results indicate that decerebrate ferrets are capable of acquiring a conditioned limb movement that is not a typical conditioned reflex but rather an accentuation of a component of the step cycle performed to avoid an interruption of swing phase.

Animals↗

PubMed1996

The expression of both amphetamine-conditioned place preference and pentylenetetrazol-conditioned place aversion is attenuated by the NMDA receptor antagonist (+/-)-CPP.

The present study addressed the ability of the NMDA receptor antagonist (+/-)-CPP ((+/-)-3-(2-carboxy-piperazine-4-yl)-propyl-1-phosphonic acid) to block the expression of amphetamine (AMPH)-conditioned place preference (CPP) or pentylenetetrazol (PTZ)-conditioned place aversion (CPA) in male Wistar rats. During a 4-day conditioning period, daily injections of AMPH (1.5 mg/kg, s.c.), PTZ (20 mg/kg, i.p.) and their vehicles were paired with two distinctive compartments of the shuttle box (balanced procedure). Rats pretreated with saline showed significant preference for the AMPH-paired or aversion of PTZ-paired compartments. Pretreatment with (+/-)-CPP (10-30 mg/kg, i.p.) dose-dependently blocked the expression of both CPP and CPA. These data suggest that NMDA receptors are implicated in the expression of conditioned behaviors.

Animals↗

PubMed2005

The effects of phencyclidine on latent inhibition in taste aversion conditioning: differential effects of preexposure and conditioning.

Latent inhibition (LI) is a behavioural procedure in which preexposure to a stimulus not followed by reinforcement retards subsequent conditioning to this stimulus when it is paired with reinforcement. Changes in LI thus reflect greater or lesser retardation of learning which essentially implies a potentiation or an attenuation of the LI effect. LI has proved sensitive to psychotomimetic and antipsychotic treatment, which has encouraged its use to model learning and attention deficits in schizophrenia. In the present study, experiments were conducted to evaluate the effects of the psychotomimetic drug, phencyclidine (PCP, 2 mg/kg), and compare it with D-amphetamine (D-AMP, 0.33 and 1 mg/kg), on LI using a conditioned taste aversion procedure. PCP was found to potentiate LI when administered acutely prior to the conditioning trails, while no such effect was observed when administered prior to the preexposure trials. D-AMP, on the other hand, disrupted LI possibly due to a failure to induce a persistent taste aversion conditioning.

Analysis of Variance↗