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PubMed1992

Diprenorphine as a stimulus in drug discrimination learning.

Using the conditioned taste aversion baseline of drug discrimination learning, animals were trained to discriminate diprenorphine from distilled water. In subsequent generalization tests, the opiate antagonists naltrexone and naloxone and the mixed opiate agonist/antagonist nalorphine substituted for the diprenorphine stimulus in a dose-dependent manner, while the opiate agonist morphine and the nonopiate pentobarbital failed to substitute even at the highest doses tested. That a range of opiate antagonists substituted for the diprenorphine stimulus (and an opiate agonist and a nonopiate failed to substitute) suggest that diprenorphine's antagonist properties may mediate the discrimination, presumably by blocking endogenous opiate activity. The ability of these drugs to substitute for the diprenorphine stimulus may also be a function of this receptor activity. The differences in the specific generalization patterns reported in the present assessment and those of earlier reports were discussed.

Animals↗

PubMedDate not supplied

The effect of beta-(Tyr9)melanotropin-(9-18) on active avoidance behavior, electroconvulsive shock-induced amnesia and T-discrimination learning of rats.

The effect of beta-(Tyr9)melanotropin-(9-18) was investigated on active avoidance behavior, electroconvulsive shock (ECS)-induced amnesia and T-discrimination learning in rats. The decapeptide inhibited the extinction of active avoidance behavior. It was also able to block ECS-induced amnesia if the treatment was performed immediately, or 4 hr or 20 hr after the ECS. In the T-discrimination paradigm the peptide facilitated spatial discrimination learning and reversal learning. These results suggest that beta-(Tyr9)melanotropin-(9-18) can influence learning and memory processes in different behavioral tests.

Amnesia↗

PubMed1989

A role for stimulus generalization in conditional discrimination learning.

In each of three experiments on discrimination learning by rats, whether or not a 10-sec target stimulus was followed by food was determined by the nature of a 2-min background stimulus that accompanied it. A conditional discrimination was employed in Experiment 1 such that background A indicated food would follow one target but not the other, whereas this relationship between the targets and food was reversed in the presence of background B. Experiment 2 employed two feature-positive discriminations. Subsequent test trials revealed that the background for one discrimination was able to enhance responding during the target for the other discrimination. Experiment 3 employed a feature-positive and a feature-negative discrimination prior to test trials in which each target was presented separately during a compound of both background stimuli. The compound enhanced responding to the target from the feature-positive discrimination and reduced it to the target from the feature-negative discrimination. We suggest that to accommodate all these findings, the best explanation is provided by a configural model of Pavlovian conditioning.

Animals↗

PubMed1988

Binocularly deprived cats are normal in visual discrimination learning in a simple apparatus.

Pattern discrimination learning was compared in three groups of cats: reared in normal conditions, reared in the laboratory with opened eyes, and deprived of patterned vision from birth. A four-choice apparatus without partitions was used. The figure of a disc was reinforced with food, whereas a cross, triangle and square were not. All groups reached criterion after similar numbers of trials and errors, indicating that in binocularly deprived cats, simple perceptual and associative learning are not impaired.

Animals↗

PubMed1988

The pretectum and visual discrimination learning in the hooded rat.

In previous studies on the effects of pretectal lesions on visual discrimination performance, the lesions have either been small or their effects confounded with damage to the adjacent thalamus and the results have been inconsistent. This study compares the effects of large pretectal lesions (PRT) with lesions in lateral (TLP) and medial (MPT) posterior thalamus on simultaneous black versus white (BW), horizontal versus vertical (HV) discrimination acquisition and low frequency flicker detection. An unoperated control group treated regularly with a cycloplegic to produce mydriasis was also tested in the discrimination learning phase. PRT lesions and treatment with the cycloplegic produced mydriasis as well as an impairment on BW. Neither group was impaired on HV. Animals with MPT and TLP lesions were impaired on BW and HV and those with TLP lesions were also impaired on flicker detection. It is concluded that the pretectum is important for visual intensity discrimination learning but the effects of lesions are due to disturbances of pupillary control. The significance of this finding for the interpretation of deficits produced by lesions elsewhere in the thalamus is discussed.

Animals↗

PubMed1990

Two-stage model of visual pattern discrimination learning in macaque monkeys (Macaca mulatta and Macaca fuscata).

To investigate the nature underlying the process of pattern discrimination learning, a series of seven experiments on seven working assumptions were undertaken. The main findings are as follows. The pattern discrimination learning consists of two time-dependent stages: The initial or first learning stage is the period of performance at chance, and the succeeding or second stage is the period of performance from just above the chance to a criterion level. The duration of the first stage is dependent on the degrees of cue-response separations, whereas that of the second stage is independent of. During the first stage, monkeys do not attend to the discriminative cue even at small cue-response separations, whereas during the second stage, they achieve pattern discrimination, or pattern perception and cognition, regardless of cue-response separations. After having learned the first pattern task with a cue-response separation, they learned new pattern tasks by means of the second stage, showing marked saving of the duration of the first stage. The findings in the present studies indicate that the first stage of learning is predominantly involved in the process of attending to the discriminative cues remote from the response site (a selective attention to the cue), whereas the second stage is concerned with the process of perception and cognition of the discriminative cue.

Animals↗

PubMed1985

Visual discrimination learning and interhemispheric transfer in the cat, as affected by 6-hydroxydopamine.

Learning and interhemispheric transfer of visual flux, pattern and form discriminations were studied in the cat after selected exposure of one suprasylvian cortex to 6-hydroxydopamine (6-OHDA). Biochemical assay using High Performance Liquid Chromatography (HPLC) two weeks after 6-OHDA revealed no discernible norepinephrine or dopamine in the treated cortex, but elevated concentrations of these transmitters in the cortex of the opposite hemisphere. Visual discriminations learned before treatment with 6-OHDA were retained at a high level using either the eye on the side of chemical lesion or the eye on the untreated side. An asymmetric deficit in learning new form discriminations was present, however, when the eye on the untreated side was used, in contrast to normal learning using the eye on the side of the hemisphere with depleted adrenergic nerve supply. Once learning was achieved using the lesioned hemisphere transfer of the engram was found to the untreated hemisphere. Thus, the unlesioned hemisphere was unable to learn normally using direct retinal input from the ipsilateral eye, but showed good capacity for learning using indirect visual input from the contralateral eye. This suggests a powerful influence of the callosum on the learning abilities of the two hemispheres, an influence proved by sectioning the callosum. Callosotomy resulted in a reversal of the discriminative capacities seen after 6-OHDA, i.e. the lesioned hemisphere was defective relative to the unlesioned hemisphere.

Animals↗

PubMed1977

Technique for assessing visual discrimination learning in mice.

An automated technique for the study of visual discrimination learning in mice has been developed. The technique utilizes a nose-poke as the operant response. The nose-poke response requires no shaping, has a relatively high operant level and can be used to measure preacquisition exploratory behavior. CD-1 mice acquired a simultaneous brightness discrimination readily but a successive brightness discrimination proved more difficult. A 20 sec intertrial interval was optimal for acquisition of the simultaneous discrimination. Reversal learning was slow. This procedure should prove useful in the study of the effects of pharmacologic and toxic agents on learning and performance in both weanlings and adult mice.

Animals↗

PubMed1991

Attentional aspects of classroom behavior and discrimination learning.

Teachers' ratings of their mentally handicapped pupils' classroom behavior were examined as correlates of the child's performance on a discrimination learning task. Teachers completed the 23-item version of the Attention/Distraction Inhibition/Excitation Classroom Assessment Scale (ADIECAS) for a total of 77 pupils. Factors identified as attention/distractibility and responsivity to consequences correlated significantly with number of errors and number of trials to criterion during acquisition of a simultaneous visual discrimination. Attention/distractibility scores also correlated significantly with number of dimensions "attended to" during discrimination learning.

Adolescent↗

PubMed1975

Genetic analysis of water maze discrimination learning for Mus musculus: polygenes and albinism.

Recombinant inbred strains, their progenitor strains and reciprocal F1 hybrids were given thirty spatial discrimination learning trials in the water maze. The pattern of RI strains in relation to the reciprocal F1 hybrids and the progenitor strains, and differences among strains, suggested that different sets of genes affect the various components of water maze discrimination learning. There was no evidence that the albino gene influenced either inferior or superior performance. Pigmented strains performed as well as, or better than, some albino strains, and albino strain BALB/cBy differed significantly from albino strains CXBG and CXBI. The two reciprocal F1 hybrids differed from blocks 2 and 3 of discrimination trials when swimming time was used a dependent variable. Thus, it appears that performance of the F1 hybrids was influenced by paternal effects, maternal effects, or paternal maternal interactions.

Albinism↗

PubMed1976

Differences in the effects of post-trial chlorpromazine, reserpine, and amphetamine on discrimination learning in rats.

Rats were trained to perform in discrimination learning reinforced by water for 6 days, and were intraperitoneally injected with chlorpromazine, reserpine, or d-amphetamine after each training session. Although chlorpromazine at the dose levels of 0.5 mg/kg or more injected immediately after training impaired learning, the drug did not affect learning when it was injected 60 min after training. Reserpine and amphetamine also impaired learning, but delaying the time intervals between training and injection to 60 min or more had no influence on this learning impairment. Post-trial chlorpromazine and amphetamine had no effect on, but reserpine decreased, motility in the subsequent training session. Chlorpromazine had no effect on water intake in the subsequent session, but reserpine and amphetamine decreased water intake at the dose levels that impaired learning. It was concluded that all three drugs impaired learning, but differed in their effects on learning; chlorpromazine impaired learning by a specific effect on learning itself; reserpine, by a non-specific effect on behavior due to a long acting sedation; and amphetamine, by an effect to decrease the motivation to drink water. The specific effect of chlorpromazine could be related to the hypothesis of "memory trace" synthesis.

Animals↗

PubMed1989

Telencephalic function implicated in food-reinforced color discrimination learning in the goldfish.

The effects of telencephalic ablation on the learning of color discrimination were studied in the goldfish (Carassius auratus) to determine the role of the telencephalon in the learning. The performances of normal and telencephalonless animals were compared in relation to their instrumental training rates. The animals were trained to discriminate between blue and green stimulating patches presented simultaneously. Normal and telencephalonless animals which underwent ten trials per day were unable to discriminate between the stimuli, but animals which underwent thirty trials showed learning. In animals which underwent twenty trials, there was a clear difference between the performances of normal and telencephalonless animals: the normal ones were able to learn, but the telencephalonless ones showed a significantly impaired learning ability. These results suggest that the telencephalon is not essential for the learning, but is supplementary in that it facilitates integration of neural events in extratelencephalic areas that are necessary for the instrumental process involved in color discrimination learning.

Animals↗

PubMedDate not supplied

Testing strategies in behavioral teratology: II. Discrimination learning.

Male and female Wistar rats exposed to methylmercury chloride prenatally via drinking water (1.5 and 5.0 mg/l) were tested in a microcomputer-directed learning task (visual discrimination reversal) at the age of two months. Differences were observed between control and high dose group for several parameters, the most obvious being an increase in passiveness and in response latency, as well as a decrease in intertrial interval response rates in the methylmercury group. No effects were seen in the low dose group. Performances of male and female animals were quite similar. However, females showed longer response latencies and passiveness scores were somewhat higher than in males.

Amphetamine↗

PubMed1975

Visual discrimination learning in cats with different early visual experiences.

Simultaneous object discrimination learning in an alimentary situation was strongly impaired in cats deprived from birth of patterned visual experience. The same impairment was observed in cats with experience limited to those objects that were used later in the discrimination task. Some impairment was also present in cats which were reared with opened eyes in the laboratory as compared with normal cats, that spent the early period of life outside of the laboratory. It is concluded that the deprived cats were impaired mainly because of the lack of opportunity during early development to use visual cues in alimentary tasks.

Animals↗

PubMed1976

Theoretical and methodological considerations on drug discrimination learning.

A method is described which allows the assessment of discriminative stimulus properties of drugs, and the ability of amphetamine (0.16 mg/kg s.c.), chlordiazepoxide (5 mg/kg p.o.), desipramine (5 mg/kg s.c.), and haloperidol (0.02 mg/kg s.c.) to produce a discriminative stimulus complex (DSC) is evidenced. The method is found to yield clear-cut data that are specifically related to drug discrimination learning without being possibly confounded by state dependent effects. In addition, the experimental procedure is designed so as to provide an appropriate measurement of operant response modulating drug effects.

Amphetamine↗

PubMed1985

Visual discrimination learning in mentally handicapped adults: comparative effects of two-choice and multiple-choice training methods on stimulus generalization performance.

The hypothesis that in mentally handicapped subjects a multi-choice discrimination learning method would result in superior generalization performance to the traditional two-choice method was investigated experimentally. Twenty-four mentally handicapped adults matched for age, intelligence and duration of institutionalization were divided into two equal groups and given visual discrimination training using a differential reinforcement, prompt-fading procedure. The groups were allocated separately to a two-choice and four-choice training condition in which the discriminative stimulus was associated with one and three non-discriminative stimuli respectively. Following training, stimulus discrimination performance was compared on a generalization test comprising increasing levels of distraction. The results showed a clear advantage for multi-choice training over two-choice. However, it was found that during generalization testing discriminative performance deteriorated as a function of increasing distraction in both groups, suggesting an underlying selective attention defect. Such a defect may be characteristic of stimulus generalization performance in the mentally retarded. Multi-choice discrimination learning appeared partly to counteract major generalization failure when the ratio of non-discriminative to discriminative stimuli was high.

Adult↗

PubMed1979

Discrimination learning without short-term memory: dissociation of memory processes in pigeons.

Pigeons were trained to perform delayed matching to samples of food and no food when each sample concurrently served as the outcome of a discrimination learning trial which immediately preceded each matching trial. Ambient light presented during the delays after the samples of food or no food severely disrupted matching but had no effect on the rate of discrimination learning.

Animals↗

PubMed1975

Prehatch color stimulation effects on color pecking preferences and color discrimination learning in white leghorn chicks.

Four experiments assessed the effects of stimulating chick embryos with colored light at 2 intensity levels. Both posthatch color pecking preferences (Experiments 1 and 2) and color discrimination learning (Experiments 3 and 4) were unaffected. These results affirm and extend a prior finding of no pre- and posthatch colored light stimulation effect on posthatch color preferences in ducklings. The color pecking preferences found replicated prior findings with chicks. However, they differed from the approach color preferences observed in color discrimination learning.

Animals↗