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Results for “Reversal Learning”

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At least 847 records · Page 47Linked to original sources
PubMed1989

Effect of piracetam, a nootropic agent, on discrimination learning deficits induced by parental undernutrition and environmental impoverishment in young rats.

The study was conducted on 64 Charles Foster albino rats which were equally distributed into 8 even-matched groups, following a 2 x 2 x 2 factorial design by varying three independent factors at two levels: nutrition--normal and undernutrition, environmental--enrichment and impoverishment, and drug treatment--vehicle and piracetam (100 mg/kg, ip). Prenatal nutrition was induced by restricting the mother's food intake. The environmental enrichment/impoverishment and the vehicle/drug treatments were given during the postweaning period of the rat pups. The animals were subjected to original and subsequent reversal brightness discrimination learning tests in a single unit T-maze at 8-9 weeks of age. The results indicate that undernutrition and environmental impoverishment significantly attenuated the original discrimination as well as the reversal discrimination learning. Piracetam treatment improved the learning performance of normally reared rats and also attenuated the original and reversal learning deficits induced by prenatal undernutrition and postnatal impoverishment. The results indicate that piracetam may be useful in memory deficits induced by malnutrition.

Analysis of Variance↗
PubMed1975

Excess neonatal thyroxine: effects on learning in infant and adolescent rats.

Previous reports have suggested that neonatal thyroxine administration may enhance learning ability in rats as infants but the rats become deficient in learning as they grow older. This experiment compared neonatally thyroxine-injected rats with injected and nonhanded controls on passive and active avoidance and a geotactic cold-escape discrimination. Thyroxine-injected infant rats were superior to controls on active avoidance, inferior on passive avoidance, and equal on discriminated escape. Adolescent rats which had received postnatal thyroxine were inferior to controls in Lashley III maze acquisition whether or not they had received supplementary thryoxine at the time of training. These data suggest that differences in locomotor activity, rather than in learning ability, account for early behavioral effects and that changes other than endocrine disturbances account for the adult deficits. The results are compatible with previous contentions that excess neonatal thyroxine disrupts the timing of brain development.

Age Factors↗
PubMed1986

Learning impairment following lesion of the basal nucleus of Meynert in the marmoset: modification by cholinergic drugs.

Five common marmosets (Callithrix jacchus) received unilateral ibotenic acid lesions of the basal nucleus of Meynert (nBM). Seven days later, choline acetyltransferase activity was significantly reduced by 50% in the frontal and temporal neocortex, 40% in the amygdala, and approximately 30% in the motor, parietal and occipital cortex in the ipsilateral hemisphere. Four marmosets receiving equivalent bilateral ibotenic acid lesions were severely impaired on new visual object discrimination learning and on relearning an object discrimination learnt prior to surgery when compared with operated controls. New learning in lesioned animals was substantially improved by i.m. administration of the cholinergic agonist arecoline. Lesioned animals' learning ability improved with time but these animals were then differentially sensitive to the disruptive effect of scopolamine on discrimination learning. These results show that lesions of the nBM which destroy the rising cholinergic pathways impair learning ability but that this ability can be substantially restored by administration of a cholinergic agonist.

Acetylcholine↗
PubMed2005

Acupuncture improved cognitive impairment caused by multi-infarct dementia in rats.

Recent studies have demonstrated that acupuncture is feasible to treat vascular dementia (VD). The aim of this study was to present behavioral evidence that acupuncture could improve the learning and memory of multi-infarct dementia rats. The pattern of multi-infarct dementia in rats was made by injecting homogeneous emboli into the internal carotid artery. Of them the rats which showed damage in learning and memory (n = 43) were randomly allocated to 3 groups: impaired group (n = 14), acupuncture group (n = 15) and placebo-acupuncture group (n = 14). Moreover, normal group (n = 15) and sham-operated group (n = 15) were set as control groups. The acupuncture group was given acupuncture, which consisted of Tanzhong (CV17), Zhongwan (CV12), Qihai (CV6), Zusanli (ST36) and Xuehai (SP10). Morris water maze test was employed to assess spatial discriminational ability per group respectively and to analyze the curative effects of acupuncture. Compared to the impaired and placebo-acupuncture groups, no cognition impairment was found in the normal and sham-operated groups, and the statistic analysis showed that there were significant differences between normal and impaired groups in ANOVA. Shortened mean escape latency was detected in the acupuncture group compared with the impaired group during the same trial days. Search strategy changed from random pattern adopted by impaired and placebo-acupuncture rats to tendency or linear pattern popular in normal group. The present results suggested that the acupuncture exerted a protective effect on cognitive impairment caused by cerebral multi-infarction in rats, and acupuncture has a specificity of cure. Acupuncture as a potential clinic method in treating VD should be developed and investigated in the future.

Acupuncture↗
PubMed2003

Cognitive experience and its effect on age-dependent cognitive decline in beagle dogs.

Test-sophisticated beagle dogs show marked age sensitivity in a size discrimination learning task, with old and senior dogs performing significantly more poorly than young dogs. By contrast, age differences in learning were not seen in dogs naive with respect to neuropsychological test experience. These results indicate that old animals benefit less from prior cognitive experience than young animals, which is an example of an age-dependent loss in plasticity. This finding also suggests that behaviorally experienced animals are a more useful model of human cognitive aging than behaviorally naïve animals. We also looked at the effect of a program of behavioral enrichment in aged dogs. One year of enrichment did not lead to significant differences, but after 2 years the behaviorally enriched group performed significantly better than the control group. The effect after 2 years indicates that a prolonged program of cognitive enrichment can serve as an effective intervention in aged dogs. These findings demonstrate that cognitive abilities in aged animals can be modified by providing behavioral experience, indicating that cognitive abilities remain moderately plastic, even in very old animals.

Age Factors↗
PubMed1979

Contrast, component duration, and the following schedule of reinforcement.

Experiment 1 investigated component duration in a four-component multiple schedule designed to separate the effects of the preceding schedule of reinforcement from those of the following schedule of reinforcement. The preceding schedule in the preceding component had no consistent effect regardless of component duration. The following schedule was a powerful determinant of behavior, however, with higher response rates resulting from a following period of extinction. Moreover, the effect of the following schedule was greater with short component durations, which strongly suggests that component-duration effects previously found with multiple schedules are due generally to variation in the degree of control by the following schedule. Experiments 2--4 investigated the basis of the effects of the following schedule. In some situations differential responding in the following component was the controlling variable, but in others it was differential reinforcement in the following component. The results are consistent with the view that response rate during a stimulus is inversely related to the "value" of the following component, where the calculation of value must include both primary and conditioned reinforcement.

Animals↗
PubMed1984

Behavioral effects of vasopressin.

A single case study was executed to generate hypotheses concerning the role of vasopressin in human behavior. Classic tasks of experimental psychology, introspective and electrophysiological measures were applied in twelve sessions after randomized intake of vasopressin or a placebo. Results indicate that earlier stages of information processing in terms of attentional and arousal processes could be affected by the neuropeptide. Therefore the often claimed enhancement of memory processing seems to be an indirect effect of vasopressin.

Arousal↗