Impaired Discrimination Learning Research Articles

Neonatal glutamate destroyed CA1 neurons and impaired discrimination learning in rats

Neonatal glutamate destroyed CA1 neurons and impaired discrimination learning in rats

Colour Versus Orientation Discrimination in Severely Brain-Damaged and Normal Adults

Normal adults and adults with severe, diffuse brain damage were tested on a two-choice simultaneous discrimination where either the colour or orientation of stripes on the stimulus cards was the relevant dimension. There was no overall impairment in discrimination learning by the brain-injured subjects. In the normal subjects, however, the discrimination was produced more readily for line orientation than for colour whereas the converse was true for the brain-damaged group. The present data are compared to those obtained in developmental studies and with other types of cerebral pathology.

Dichotic listening and allusive thinking.

Previous work suggests that allusive thinkers have a broader attentional process associated with weak central inhibition. The method of dichotic stimulation was used to investigate this concept. Sixty-three university students completed a battery of tests including 2 dichotic listening tasks. The Object Sorting Test was used as a measure of allusive thinking. Allusive thinkers showed a trend towards impaired shadowing performance. Mislabelling of shadow as distractor words and vice versa, on recall and recognition tasks, showed the strongest correlation with allusive thinking. Such mislabelling was considered to reflect impaired discrimination learning, and provides further support for a hypothesis relating allusive thinking to weak Pavlovaian central inhibition.

Effects of postresponse visual stimuli on visual discrimination learning in the rhesus monkey

To learn more about the mechanism (or mechanisms) involved with postresponse stimulus processing during discrimination learning, a series of studies was conducted with monkeys to determine why the combined relevant and irrelevant stimuli impair learning more than irrelevant stimuli appearing alone. It was found that: (a) the greater size and complexity of the combination of stimuli were not responsible for the greater deficit, while the presence of the relevant stimuli (S D and S Δ) within the stimulus combination apparently was; (b) the more similar the postresponse irrelevant stimuli were to the relevant stimuli the greater the deficit that resulted; and (c) monkeys that had earlier learned to discriminate the relevant and irrelevant features of a combination showed no learning impairment when this same stimulus combination was later presented after the response during a new learning problem. These results were interpreted as evidence that: (1) processes associated with learning a discrimination problem do not end with the execution of a choice response; (2) postresponse stimuli produce greater impairment in discrimination learning when they are distorted versions of the relevant stimuli; and (3) the impairment resulting from postresponse irrelevant stimuli occurs primarily when this misinformation is processed and misperceived as being relevant to learning the discrimination problem.

Effects of Alcohol on Discriminative Active Avoidance Behavior in Mice

Alcohol improved initial avoidance responses and disrupted later responses and impaired discrimination learning, but did not affect behavior if the avoidance response had been previously established.

Impairments in selective attention to visual stimuli in monkeys with inferotemporal and lateral striate lesions

Bilateral removal of inferotemporal (IT) cortex in monkeys produces a severe impairment in discrimination learning limited to the visual modality (see Mishkin 12 for a review of these findings). While the visual deficits produced by IT lesions cannot be readily attributed to sensory losses 7,16 the nature of the disorder remains unclear. Chow and Orbach 5 attempted to determine whether IT ablation is associated with losses in selective attention by use of a discrimination task in which visual stimuli are briefly exposed, but found no impairment in IT monkeys in this situation. Subsequently, it was shown that the failure to obtain visual losses in IT monkeys under these conditions could be attributed to preoperative overtraining 6,13. The present experiment reinvestigated the question of selective attention losses in IT monkeys by methods which avoid the problem of preoperative overtraining. In this experiment, monkeys with IT ablation, along with their controls monkeys with lateral striate (LS) ablation and unoperated monkeys were first trained to discriminate between two visual stimuli. Irrelevant features were then added to the stimuli in a series of tests in which the animals were required to relearn the discrimination problem. If the IT animals were to be retarded in relearning the discrimination, this might imply a loss in the ability to selectively attend to or abstract the relevant visual features.

Inferotemporal cortex and the processing of visual information in monkeys

Impairment in discrimination learning in monkeys with inferotemporal lesions is discussed in terms of a model of visual information processing. It is proposed that there is a trade-off between discrimination and encoding of stimulus input which relates to the functions of anterior and posterior inferotemporal areas.

Effects of prenatal x-irradiation on discrimination learning in the rat.

SummaryOffspring of non-irradiated rats which received a single dose of 150 r x-irradiation on 10th, 14th or 18th day of pregnancy respectively or 300 r on 18th day of pregnancy were exposed at approximately 6 months of age to a brightness discrimination problem. Data were evaluated on the basis of number of trials to criterion and number of errors for the various groups on the day when offspring of non-irradiated group reached criterion. Findings indicate that a single exposure of 150 r on 14th day or 300 r on 18th day of pregnancy significantly impaired discrimination learning performance as compared to the performance of non-irradiated rats or offspring of rats administered a single dose of 150 r x-irradiation on 10th or 18th day of pregnancy.