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PubMed1981

[Effects of various kinds of trainings on the discrimination learning in mental retarded children (author's transl)].

Effect of various kinds of trainings on the discrimination learning in which the preferred dimension was irrelevant were assessed in retarded and normal children. In the normals, the effects of the attempts which were designed to direct subject's attention at the relevant dimension before the discrimination learning were found, but not in the retardates. In the retardates who prefer forms to colors but not in those who prefer colors to forms, however, the effects of the attempts during the discrimination learning were found. The result was discussed in relation to the retardates' difficulty of switiching their attention to nonpreferred dimension and to their short-term memory deficit.

Child↗
PubMed2001

Ts65Dn mice, a model for Down syndrome, have deficits in context discrimination learning suggesting impaired hippocampal function.

The Ts65Dn mouse is segmentally trisomic for a part of mouse chromosome 16 and is a genetic model for Down syndrome and Alzheimer's disease. Although many studies have examined the learning and memory processes in Ts65Dn mice, it has yet to be determined if Ts65Dn mice are specifically impaired in learning tasks that require an intact hippocampus. Context discrimination learning is dependent on the dorsal hippocampus in mice. In this task, mice learn to discriminate two similar contexts, one of which is associated with foot shock. In the current study, Ts65Dn mice learned almost identically to what has been reported for mice with dorsal hippocampal lesions, while controls behaved similarly to sham lesioned mice. Therefore, Ts65Dn mice have learning deficits in a hippocampal dependent task that may be related to the loss of cholinergic input to the hippocampus, which occurs after 6 months of age.

Age Factors↗
PubMed1992

Conditioned taste aversions support drug discrimination learning at low dosages of morphine.

The present experiment shows that a conditioned taste aversion procedure can support discrimination learning at dosages of morphine comparable to those required to produce motivational effects. Sprague-Dawley rats were injected with 4.0 mg/kg morphine sulfate prior to a saccharin-lithium chloride pairing, and physiological saline prior to a saccharin-saline pairing. The rats avoided the saccharin solution following the administration of morphine and consumed significantly more saccharin following saline administration after four discrimination cycles. After this initial discrimination the subjects were trained with progressively lower doses of morphine. Discrimination learning was apparent at doses of 2.0, 1.5, 1.0, 0.75 and 0.5 mg/kg. Animals initially trained with 1.0 mg/kg morphine also learned the discrimination but required 10 training cycles. After this initial discrimination the subjects were trained with progressively lower dosages of morphine and showed a discrimination at a dosage of 0.5 mg/kg.

Animals↗
PubMed1978

Effect of intraventricular gamma-aminobutyric acid (GABA) on discrimination learning in rats.

Rats were trained to perform light-dark discrimination learning for a period of 6 consecutive days. GABA, an inhibitory transmitter, was administered into the lateral ventricle either immediately or 60 min after the completion of each training session. GABA, in dose levels of 100 and 150 microgram and injected immediately after the completion of the session, significantly increased correct responses in comparison with the corresponding control group, while 200 microgram of the drug had no further effect on the correct responses. When the administration of the drug was delayed by 60 min, neither 100 nor 150 microgram of GABA significantly increased correct response. Intraventricular GABA did not affect total activity or water intake which could be considered indexes corresponding to motility and motivational state, respectively. It was concluded that under these conditions GABA improves discrimination learning by its action as an inhibitory transmitter.

Aminobutyrates↗
PubMed2006

Frontal-temporal disconnection abolishes object discrimination learning set in macaque monkeys.

Two previous studies have shown that frontal-temporal disconnection in monkeys, produced by unilateral ablation of frontal cortex in one hemisphere and of visual inferior temporal cortex in the opposite hemisphere is entirely without effect on visual object-reward association learning in concurrent discrimination tasks. This is a surprising finding in light of the severe impairments that follow frontal-temporal disconnection in many other tests of visual learning and memory, including delayed matching-to-sample and several conditional learning tasks. To explore the limits of this preserved object-reward association learning, we trained monkeys on visual object discrimination learning set (DLS) prior to frontal-temporal disconnection. As a result of training with single object-reward associations, the monkeys acquired a proficient learning set, evidenced by the rapid learning of new single object-reward association problems. This rapid learning was not affected by unilateral ablations of either inferior temporal cortex alone or frontal cortex alone but was severely impaired after final surgery to complete the disconnection. Moreover, each individual monkey now learned single object-reward association problems at the slow rate at which that individual had learned such problems before the formation of learning set. This result shows that frontal-temporal disconnection abolishes visual learning set.

Animals↗
PubMed1990

Protective effect of the calcium antagonist nimodipine on discrimination learning deficits and impaired retention behavior caused by prenatal nitrite exposure in rats.

Discrimination learning behavior and retention of a passive avoidance response were studied in male adult offspring of gestating rats exposed to drinking water containing 2 g/l sodium nitrite, throughout the second half of pregnancy. Both in an auditory and visual discrimination learning paradigm NaNO2-exposed rats were inferior to controls. The long-term retention of a passive avoidance response was also impaired. The acquisition of simple learning tasks was not significantly disturbed. The concomitant prenatal daily treatment with the calcium antagonist nimodipine in a dose of 10 mg/kg p.o. interfered with the nitrite neurotoxicity and prevented the development of adult behavioral deficits. The results support the hypothesis that Ca2+ homeostasis of neurons is an important factor for normal development of brain and behavior.

Animals↗
PubMed2005

Hippocampal cytochrome oxidase activity of rats in easy and difficult visual discrimination learning.

The present study investigated the functional involvement of the rat hippocampal formation in easy and difficult visual discrimination learning by measuring regional brain cytochrome oxidase (C.O.) activity, an index of neuronal metabolic activity. The results showed that learning was related to C.O. activity in the CA field and the dentate gyrus of the hippocampal formation of rats in the difficult discrimination, whereas learning was related to C.O. activity only in the dentate gyrus of rats in the easy discrimination. The results suggest that difficult visual discrimination learning required greater involvement of the hippocampal formation than easy visual discrimination learning.

Animals↗
PubMed1989

Further studies of hippocampal representation during odor discrimination learning.

The contribution of hippocampal and nonhippocampal memory processing to simultaneous-cue odor discrimination learning was assessed. In this task, rats with hippocampal system damage consequent to fornix lesions (fornix rats) were severely and persistently impaired in discrimination learning, acquisition of learning set, and concurrent discrimination, although they occasionally solved some problems at a normal rate. By using those problems on which fornix rats succeeded, to permit comparisons of performance strategies with normal rats, differences between groups were shown on response latency measures and on probe trials involving the novel pairing of familiar odors. Normal rats had a bimodal distribution of response latencies, and their latency depended on where the S+ was presented. Fornix rats had short response latencies and responded equally quickly wherever the S+ was presented. Furthermore, when the representation of familiar S+ and S- odor pairs was challenged in probe trials, normal rats responded appropriately to the correct stimulus, whereas fornix rats behaved as if presented with a new odor pair. These data provide support for the view that the hippocampus participates in the representation of relations among odor (and other) stimuli and among other experiences and that it permits the flexible use of these representations in new contexts. In contrast, memory processing outside the hippocampal system can represent only the significance of individual stimuli and can be revealed only in a repetition of the original learning event.

Animals↗
PubMed1991

A demonstration of the graded nature of the generalization function of drug discrimination learning within the conditioned taste aversion procedure.

Although control of discriminative performance will often generalize to different doses of the training drug or to drugs from the same class as the training drug, the nature of this generalization is unknown. Prior work has suggested that the generalization is primarily quantal in nature with animals displaying either vehicle-appropriate or drug-appropriate responding, depending upon their detection of the drug stimulus. It has been questioned whether this quantal nature of generalization reflects a characteristic response to drug stimuli or whether such responding is a function of the specific training and testing procedures used to establish and measure drug discrimination learning. The present paper evaluated this issue by analyzing the generalization functions of individual subjects trained and tested within one specific drug discrimination procedure, i.e. the conditioned taste aversion design. Responding within this design was generally graded. It is clear that quantal responding is not a necessary outcome of drug generalization assessments and that the nature of generalization in drug discrimination learning is a function of the specific procedure utilized in training and testing the discrimination. The results of the present analysis are discussed in terms of other recent work reporting graded functions.

Journal Article↗
PubMed1988

Effect of nimodipine on brightness discrimination learning test in Wistar Kyoto and spontaneously hypertensive rats.

Nimodipine (Nimotop) was administered to spontaneously hypertensive rats (SHR) in order to investigate its ameliorative effect on central nervous disorders associated with hypertension. Discrimination learning was used as the dependent variable. In normotensive Wistar Kyoto rats, the ratio of correct: incorrect responses in a brightness discrimination was not different between the nimodipine group and the vehicle group. However, SHR, which displayed decreased discrimination learning ability under control conditions, showed a remarkable improvement in discrimination learning under the influence of nimodipine. This was probably because the vasodilative action of nimodipine produced improvements in circulation in various organs including the brain, which in turn influenced learning ability. Nimodipine has very effective actions on learning performance that low levels of discrimination ability in SHR might be improved on learning performance on schedule controlled learning task.

Animals↗
PubMed2001

Impaired conditional discrimination learning in schizophrenia.

Learning deficits have repeatedly been found in patients with schizophrenia. Eyelid conditional discrimination learning (ECDL) is a test of discriminative aversive conditioning and places minimal demands on motivation. An ECDL task was used to examine residual and paranoid type individuals with schizophrenia and age- and gender-equivalent healthy controls. In the experiment two differently colored light stimuli were randomly presented. Only one of the stimuli (in reinforced trials) was followed by an aversive airpuff to the cornea, as opposed to unreinforced trials where the stimulus was not followed by an aversive airpuff. Conditioned responses develop to both trial types during the course of the experiment. These conditioned responses consist of reflectory eyelid closures already upon light presentation. The patients showed significantly impaired conditional discrimination learning abilities. There was no significant difference between the results in the two schizophrenia subtypes. Patients failed to increase response frequencies on reinforced trials during the course of the experiment, while controls showed appropriate conditional discrimination ability. Thus the results show an impairment of adequate behavior modification in an aversive conditioning task in individuals with schizophrenia. It is concluded that ECDL might be a trait marker for schizophrenia.

Adult↗
PubMed1994

Effect of nutritional and environmental restrictions on discrimination learning behaviour of juvenile rats.

Effects of nutritional and environmental restrictions on discrimination learning in a single unit black/white T-maze were studied in albino rats. Nutritional restrictions were imposed by 25 and 50% dietary restriction and environmental restrictions were given for 3 and 6 weeks. Both the restrictions were imposed at 46th day after birth. Long-term (6 weeks) environmental restriction significantly impaired the original and reversal discrimination learning, however, short-term (3 weeks) restriction had no effect. Nutritional (dietary) restrictions, on the other hand, had no effect on both learning performances. Interaction between these two variables was also statistically insignificant.

Animals↗
PubMed1985

[Effect of idebenone (CV-2619) on brightness discrimination learning in rats with central serotonergic dysfunction].

The effect of 6-(10-hydroxydecyl)-2, 3-dimethoxy-5-methyl-1, 4-benzoquinone (idebenone, CV-2619) on brightness discrimination learning of the operant type was examined in rats with central serotonergic dysfunction. The animal model was produced by feeding Wistar rats a diet deficient in tryptophan (a precursor of serotonin) as the control group. The control rats with central serotonergic dysfunction showed lower ability to learn the discrimination task (multiple VI 15 seconds extinction schedule) than normal feeding rats. Rats which were chronically administered with idebenone (60 mg/kg/day) admixed with the tryptophan deficient diet were used as an experimental group. In the control and experimental groups, total responses (R+ + R-) were significantly increased in the early stage of learning test period, compared with the normal rats. In the late stage of the learning periods, the numbers of R-decreased in idebenone-treated group but not in control group. Therefore, the correct response ratio [( R+/(R+ + R-)] X 100) was significantly higher in the treated group than in the control. The results suggest that idebenone, which has an improving action on cerebral energy metabolism and a stimulating action on central serotonergic turnover, may exert an ameliorating effect on impaired discrimination learning in rats with central serotonergic dysfunction.

Animals↗
PubMed1990

Effects of l-glutamic acid diethyl ester on discrimination learning in rats.

The acquisition of a visuo-tactile simultaneous discrimination task for food reward was evaluated in male albino rats given 0, 120, 240 and 360 mg/kg of l-glutamic acid diethyl ester, an antagonist of quisqualate and kainate receptors. There was an increase in the number of trials to reach the criterion and in the number of errors at the two highest doses of l-glutamic acid diethyl ester in comparison to the two lowest doses. These results indicate a possible role for non-NMDA amino acid receptors in discrimination learning.

Animals↗
PubMed1978

The effect of change in stimuli on the transfer of dimensional pretraining to the discrimination learning of kindergarten children.

Kindergarten children were given verbal pretaining prior to a simultaneous discrimination learning task under 1 or 2 stimulus conditions. For half the children, the stimuli were changed from the pretaining task to the criterion task; for the other half, the stimuli were identical in the 2 tasks. During pretaining, the children learned to label the values of the dimension that would be either relevant, constant, or irrelevant in discrimination learning. When the stimuli were identical in 2 tasks, pretaining produced significant facilitation and interference effects in discrimination performance. The pretaining effects in the changed-stimulus condition were greatly attenuated and nonsignificant. The relation of these results to earlier findings and to studies of dimensional attention in general is discussed.

Child↗
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↗
PubMed1983

Ecological validity of laboratory-type discrimination-learning tasks.

Brooks and Baumeister (1977a, 1977b) have questioned the ecological validity of laboratory-type research on discrimination learning, memory, and other cognitive processes. Their criticisms were rebutted by House (1977). The present report established the relationship among learning and retention of two-choice discrimination tasks, "real-life" adaptive behavior in an institution, and IQ. These measures were substantially interrelated, and we concluded that laboratory-type discrimination-learning tasks have ecological validity.

Discrimination Learning↗