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At least 19 recordsLinked to original sources
PubMed1991

Spatial learning, discrimination learning, paw preference and neocortical ectopias in two autoimmune strains of mice.

NZB and BXSB mice were given a battery of behavioral tests including paw preference, water escape, Lashley III maze, and discrimination learning. Their brains were then evaluated for cortical ectopias. The incidence of ectopias was 40.5% in NZBs and 48.5% in BXSBs. In the NZB strain left-pawed ectopic mice (both male and female) had the fastest swimming time in the water escape test, while right-pawed ectopics were the slowest. The same findings were obtained for left- and right-pawed ectopic BXSB males, but not for the females. However, on discrimination learning the BXSB males had the exact opposite pattern: right-pawed ectopics were the best learners while left-pawed ectopics were the worst. Male BXSBs and both male and female NZBs were manifesting autoimmune disease at the time of testing, while female BXSBs were not, suggesting that autoimmunity is a necessary background condition for the differential expression of ectopias and paw preference upon learning processes. The finding that the left-pawed ectopic BXSB mice, who were the poorest learners in the non-spatial discrimination learning test, learned best in the spatial water escape test is in agreement with the Geschwind hypothesis that pathological events during brain development may, in some instances, produce superiority of function.

Animals↗
PubMedDate not supplied

Drug effects on sucessive discrimination learning in young chickens.

Chicks were trained to avoid pecking either a red or a blue bead in a one-trial avoidance task by coating one bead with methy anthranilate. They avoided the aversant bead on retention tests 10 to 180 min or 24 hr after learning, but not the neutral bead. Intracranial administration of ouabain or cycloheximide (CXM) 5 min before learning resulted in decay in retention after 10 and 30 min respectively following learning, discrimination being effective prior to those times. In a second experiment, chicks were trained on three physically distinct beads, two of which were made aversive during the learning period, the training trials separated by an hour. Saline-treated chickens retained memory of both aversive beads on retention trials 180 min later. CXM- and ouabain-treated chickens showed loss of memory for the bead associated with the drug but showed retention of the task which was not associated with the drug.

Animals↗
PubMed1990

Picture recognition vs. picture discrimination learning in monkeys with medial temporal removals.

Three monkeys with complete ablations of temporal-lobe limbic structures and three unoperated controls were compared in an automated testing apparatus for their ability to remember pictures presented between 1 and 180 seconds previously, as well as to learn picture discriminations in which successive trials with a given pair were separated by either 20 seconds or 24 hours. The operated animals were not impaired in picture discrimination learning under either condition and they were not impaired in picture recognition memory up to about 10 seconds. At 10 seconds and beyond, however, the operated animals showed rapid deterioration of picture memory. The results demonstrate that the limbic system's selective contribution to learning and retention uncovered initially with objects applies equally to pictures, this contribution being essential for recognition memory but not for discrimination habits. The results demonstrate further that, as in humans, temporal-lobe limbic structures are essential for recognition only when the retention test exceeds the immediate memory span of a few seconds.

Animals↗
PubMedDate not supplied

Effects of two ACTH analogs on successive odor discrimination learning in rats.

Olfactory discrimination learning has been shown to provide a powerful tool to investigate the mechanisms involved in the formation, storage and retrieval of information in rodent CNS. In the present study we tested the effects of two ACTH analogs, which were previously reported to influence the processes of learning and memory, on various olfactory learning tasks. The ACTH(4-9) analog HOE 427 produced an apparent increase in storage of olfactory information as shown by the difficulty experienced by the animals to rapidly reverse their behavioral responses to previously learned odors. Similarly, the ACTH (4-9) analog ORG 2766 appears to enhance the storage of olfactory information when administered either before or after the learning trials. These data are consistent with the notion that ACTH and related analogs facilitate performance in a variety of learning tasks. In addition, our results suggest possible mechanisms by which some neuroactive peptides might modulate learning and memory processes in the CNS.

Adrenocorticotropic Hormone↗
PubMed1991

Amygdalectomy and ventromedial prefrontal ablation produce similar deficits in food choice and in simple object discrimination learning for an unseen reward.

Cynomolgus monkeys (Macaca fascicularis) with either bilateral amygdalectomy or bilateral ventromedial prefrontal cortical ablations showed abnormal choices between apple, lemon, olive, and meat. Not only did they choose meat or olive more often than normal animals, but also their choices were less consistent from trial to trial than the normal animals' choices were. The same animals were subsequently tested for their ability to learn 2-choice simultaneous visual discriminations between objects which they could suck. The positive object yielded fruit juice, which entered the mouth directly without being seen. Both groups of animals with lesions were severely impaired in this discrimination learning task. The reason why amygdalectomy has little effect on simple object discrimination learning in the Wisconsin General Test Apparatus, we suggest, is that the animal can there associate the visual discriminanda with the visual properties of the food reward, a mechanism which is not available when the reward is unseen. These results add to existing evidence of a close functional relationship between the amygdala and the ventromedial prefrontal cortex, and they support the proposal, derived from previous work, that the amygdala is important for associating visual stimuli with the incentive value of reinforcers.

Amygdala↗
PubMedDate not supplied

Influence of maternal chlorpromazine on discrimination learning in rat offspring.

Light-dark discrimination learning in rat offspring born to mothers treated with chlorpromazine was studied. Daily doses of 16 mg/kg, administered from gestation day 17 to day 21, had no effect on the acquisition of lever press responses and on the original discrimination learning. However, acquisition of the reversal learning was retarded. The same dose administered during the nursing period did not produce such behavioral changes. The results indicate that high doses of chlorpromazine administered during the peripartum period might cause learning impairment in the offspring.

Animals↗
PubMed1990

Concurrent and sequential pattern discrimination learning by patients with Korsakoff amnesia.

Patients with Korsakoff's syndrome and alcoholic controls learned to discriminate sets of pairs of patterns presented concurrently, in order to test predictions based on monkeys' performance in similar tasks following medial temporal or diencephalic lesions. In Experiment 1 the subjects learned a 2-pair, a 6-pair and a 10-pair set; the Korsakoff group were impaired on the first and last, but not on the second set. In Experiment 2, the same subjects learned single pairs sequentially, and 2-pair and 8-pair sets concurrently. The effect of 2 types of feedback for correct responses (visual or non-visual) was also compared. The Korsakoff patients were markedly poorer than controls under all conditions; the type of feedback made little difference. In several respects the patients' impairment differed from what had been predicted from the animal experiments.

Alcohol Amnestic Disorder↗
PubMed1990

Partition between stimuli slows down greatly discrimination learning in binocularly deprived cats.

Pattern discrimination learning was compared in cats reared in a normal environment during the first months of life (N cats), control cats reared in the laboratory with opened eyes (C cats), and cats deprived binocularly of patterned vision from birth (BD cats). A two-choice apparatus was used for training. In Expt. I the cats had been trained without a partition between stimuli and retrained with the partition. In Expt. II the partition was used from the beginning of training. The partition slowed down the learning in all groups. However, the BD cats were much more affected than N cats, and C cats seemed to be more affected than N cats and less than BD cats. In BD and C cats the number of errors of entering an incorrect alley without pushing the gate was increased. In contrast, when the partition was absent and discrimination very simple (stimulus vs no stimulus), the BD cats seemed to master the task even more quickly than N and C cats. The results suggest that the deficit produced by the partition consisted largely in a difficulty in rapid choosing a correct directional response at distance. In BD cats the mechanism of the deficit was complex.

Animals↗
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↗
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↗
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↗
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↗
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↗