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At least 703 records · Page 39Linked to original sources
PubMed1976

Age differences in aversively motivated visual discrimination learning and retention in male Sprague-Dawley rats.

Rats 3, 7, 12, and 24.5 mo. old were trained to an 11/12 correct initial response criterion on a shock-motivated light-dark discrimination. Eight days later they were retrained to the same criterion. Original learning and relearning rates were not correlated, but both decreased linearly with increasing age. Ray and Barrett (1973) recently reported that, while year-old rats made fewer avoidances than younger animals on a shock-motivated discrimination, they appeared to have learned equally well, since there were no differences in number of correct initial responses. They suggested that avoidance scores may reflect performance factors and that learning decrements with age might not occur if the correct initial response measure were used. The present study demonstrates that this is not the case; when rats as old as 24.5 mo. are tested there are clear age-related deficits in number of correct initial responses.

Aging↗
PubMed1968

Discrimination learning, the peak shift, and behavioral contrast.

A discrimination between two successively alternating stimuli was trained under conditions that maintained equal frequencies of reinforcement in the presence of each of the discriminative stimuli (S1 and S2) but that also reduced the rate of responding to S2. These conditions included a multiple variable-interval differential-reinforcement-of-low-rate schedule and a multiple variable-interval variable-interval schedule in which responses to S2 were punished. Whenever the rate of responding to S2 was reduced, rate of responding to S1 (behavioral contrast) increased, and the peak of a subsequently obtained generalization gradient did not occur at the expected location (between S1 and S2) but was displaced away from S2, below S1. Discrimination training in which the frequencies of reinforcement earned in S1 and S2 were not equal (variable-interval 1-min variable-interval 5-min training) produced contrast and the peak shift only if the rate of responding to S2 had been reduced, as after non-differential reinforcement in which variable-interval 1-min schedules were correlated with S1 and with S2. It was concluded that a sufficient condition for the occurrence of behavioral contrast and the peak shift was reduction of the rate of responding to one of two alternating discriminative stimuli and that a peak shift will occur only if contrast had occurred during discrimination training.

Journal Article↗
PubMed1969

Conditional discrimination learning in the pigeon.

Four pigeons received conditional discrimination training in which reinforcement contingencies were related to specific combinations of color and form, but were unrelated to either color or form considered separately. During discrete-trial training, each response in the presence of two of four color-form displays produced reinforcement and terminated the trial; responding to the other two displays was never reinforced, and each such response prolonged the particular trial on which it occurred. Subsequently, the subjects received multiple-schedule training in which responding to either of the displays previously associated with reinforcement was now reinforced on a variable-interval schedule, and extinction was the schedule again correlated with the other two displays. After differential responding to the stimuli was clearly evident, intensity of the combination displays was changed in subsequent training sessions. Complex stimulus control was generally maintained across variation in intensity, although there were temporary disruptions in performance associated with onset of some of the intensity changes. Finally, a component-stimulus test revealed considerably more responding to the forms than to the colors.

Journal Article↗
PubMed1984

An involvement of acetylcholine in object discrimination learning and memory in the marmoset.

Five marmosets (Callithrix jacchus) were tested, using a Wisconsin General Test Apparatus, on a series of junk object visual discrimination tasks, including new learning, 24-hr reversal and 24-hr retention. The effects of administering the cholinergic receptor blocking agent, scopolamine either just before or immediately after the new learning task, or just before the 24-hr reversal and retention tasks, were assessed. Results suggest that scopolamine impairs new learning and impairs the encoding of new information in long term memory. Some evidence of a mild retrieval deficit under scopolamine was also seen, while state-dependent effects were not apparent.

Acetylcholine↗
PubMed1992

The performance of postencephalitic amnesic subjects on two behavioural tests of memory: concurrent discrimination learning and delayed matching-to-sample.

The performance of a group of three postencephalitic subjects with anterograde amnesia was examined on a series of concurrent visual discrimination problems and on a test of visual recognition, delayed matching-to-sample. These tests were chosen as they have been used to assess experimental models of anterograde amnesia in nonhuman primates. In comparison with a group of normal subjects the postencephalitic group were impaired on the more difficult concurrent discrimination problems. They also performed poorly on the matching-to-sample task when given lists of items to remember or given increased retention intervals. The pattern of performance of the postencephalitic group matched closely that of a group of Korsakoff subjects, indicating that these behavioural tests are equally sensitive to different types of anterograde amnesia.

Adult↗
PubMed1991

Brightness-discrimination learning in cats is influenced by early visual deprivation.

A two-choice apparatus for food reward was used. Normal and visually deprived cats were trained to discriminate white and black cards. After the animals had reached criterion, the contrast difference between the cards was diminished in steps. When the brightness ratio had been reduced to 1.8, discrimination was impaired in the deprived cats and not in the normally raised cats.

Animals↗
PubMedDate not supplied

Oral tacrine administration in middle-aged monkeys: effects on discrimination learning.

We studied the effect of chronic, oral administration of 1,2,3,4 tetrahydro-9-aminoacridine (THA), an anticholinesterase, on the acquisition of a color discrimination task in five monkeys (Macaca radiata), aged 13-19 years. A two-phase experiment was performed: initially, one animal was used and served as his own control in a multiple dose, crossover, placebo controlled trial, designed to establish a dose-response curve and an optimal dose range based on THA serum concentrations. Thereafter, four monkeys were given the optimal dose of THA (5.0 mg/day) determined previously while learning up to four color pair discriminations. They also learned up to four other color pair discriminations while on placebo. Two monkeys received THA first, then placebo; the others received placebo first, then THA. No order effects were noted. When combined scores for THA tests were compared to their placebo scores, the difference was significant at p less than 0.01 with all four THA treated monkeys requiring fewer trials to reach learning criterion. These results indicate that THA has a significantly positive effect on the acquisition of a color discrimination task.

Administration, Oral↗
PubMed1989

Early-life malnutrition impairs the performance of both young and adult rats on visual discrimination learning tasks.

Previously malnourished young (20-40-day-old) and mature (70-77-day-old) rats were compared on position, brightness, and pattern discrimination problems using an aquatic version of the Lashley jump stand. Malnutrition did not affect performance on the position discrimination. In contrast, previously malnourished 24-34-day-olds failed to solve the brightness discrimination, 40-day-olds were impaired on the brightness problem, and 40-77-day olds were impaired on the pattern problem. The impaired performance of the 40-day-olds on the brightness problem was eliminated by prior training on the pattern discriminations, and the impaired performance of the 70-day-olds on the pattern discrimination could be eliminated if they were first trained on the brightness problem. These impairments were attributed to the effects of early-life malnutrition on the maturation of attention processes that enable the rat to suppress responding to irrelevant cues. The relevance of a contextual-organismic perspective for understanding the effects of early-life malnutrition was discussed.

Age Factors↗