Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Discrimination Learning”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,441 records · Page 80Linked to original sources
PubMed1999

Extinction after regular and irregular reward schedules in the infant rat: influence of age and training duration.

Greater persistence in extinction is observed following inconsistent reward compared to that observed following consistent reward, an effect termed the partial reinforcement extinction effect (PREE). We report three experiments in which the extinction rates of random partially reinforced (PRF) or continuously reinforced (CRF) infant rat pups were compared to the extinction rate of pups trained with an alternative and regular schedule of partial reinforcement, known as patterned single alternation (PSA). In PSA, subjects learn to alternate speed of responding in anticipation of the regular alternation of reward and nonreward trials in the straight alley runway. In Experiment 1, 17-day-old PSA subjects showed CRF-like extinction rates; whereas in Experiment 2, in which extinction was initiated early in training prior to the onset of the PSA discrimination, PSA subjects showed prolonged, PRF-like extinction curves. In contrast, 12-day-old pups in Experiment 3 showed no reward-schedule-related differences in extinction, despite differences in behavior during acquisition. These results prompt a modification of Amsel's (1962) model of discrimination learning, and suggest the existence of a dissociation between different types of reward-related expectancies in the younger subjects.

Age Factors↗
PubMed1980

Loss of object discrimination after ablation of the superior colliculus-pretectum in binocularly deprived cats.

The effects of ablation of the superior colliculus-pretectum on a previously elaborated object discrimination task were compared in cats reared in normal conditions, in cats reared in the laboratory, and in cats deprived of patterned vision. The normally reared cats were least deficient postoperatively, whereas deprived cats were most deficient. Seven of 8 deprived cats failed to re-reach criterion. Previous results showed that after removal of the visual cortex deprived cats were less deficient than normally reared controls. It is concluded that in discrimination learning the function of the abnormal visual cortex of deprived cats is partially taken over by the superior colliculus-pretectum.

Animals↗
PubMed2004

Transitive inference in schizophrenia: impairments in relational memory organization.

Transitive inference (TI) describes a fundamental operation of relational (e.g., explicit) memory organization [Eichenbaum, H., Cohen, N.J., 2001. From Conditioning to Conscious Recollection: Memory Systems of the Brain. Oxford Univ. Press]. Here we investigate TI in schizophrenia (SZ), a neurocognitive disorder associated with explicit but not implicit memory dysfunction. SZ patients and healthy controls were trained on a series of learned discriminations that were hierarchically organized (A>B, B>C, C>D, and D>E). They were then tested on each training pair and two novel "inference" pairs: AE, which can be evaluated without consideration of hierarchical relations, and BD, which can only be evaluated by hierarchical relations. SZ patients and controls successfully learned the training pairs and correctly responded to the nonrelational AE pairs. However, SZ patients were less accurate than controls in responding to the relational BD pairs, consistent with the hypothesis that higher-level memory processes associated with relational memory organization are impaired in SZ. The results are discussed with respect to the relational memory model and candidate neuro-cognitive mechanisms of TI.

Adult↗
PubMed1991

Effect of amino acid supplementation to a low-protein diet on brain neurotransmitters and memory-learning ability of rats.

The supplementation of methionine and threonine to a 10% soy protein isolate diet caused sharp decreases in the concentrations of brain tryptophan, serotonin and 5HIAA (5-hydroxyindole acetic acid) (e.g., in the hypothalamus, hippocampus, amygdala, locus coeruleus and brain stem). The serum tryptophan ratio (i.e., the ratio of the serum concentration of tryptophan to the sum of the concentrations of other large neutral amino acids, such as tyrosine, phenylalanine, leucine, isoleucine, valine and methionine) significantly decreased. The changes in catecholamines were small on the supplementation of amino acids to the soy protein diet. In the brightness-discrimination learning test, the number of total responses (R+, correct; R-, incorrect) of rats fed the amino acid-supplemented diet increased as compared with that of rats fed the nonsupplemented diet. The correct response ratio in the primary learning test did not change, but in the reverse learning test, the response ratio of rats fed the amino acid-supplemented diet increased. Therefore, it may be considered that the learning ability is correlated with the nutritional state.

Amino Acids↗
PubMed1990

Attentional functioning and relational learning.

Stimulus properties such as similarity-dissimilarity and novelty-familiarity are inherently relational and are embedded in ubiquitous stimulus contexts. Children with mental retardation and young children without mental retardation are particularly prone to failure on relational tasks such as oddity and match-to-sample (Greenfield, 1985; Soraci et al., in press). Converging evidence from a number of studies suggest that a critical factor in the performance discrepancies between these and other children is a differential sensitivity to relational information. In these studies relational characteristics of stimulus arrays were enhanced in order to facilitate performances on such relational tasks. Findings indicate the theoretical and practical significance of perceptually based interventions that induce rapid discrimination learning.

Attention↗
PubMed1996

Locating reward cue at response manipulandum (CAM) induces symptoms of drug abuse.

Appetitive instrumental discrimination learning procedures provide for CAM (cue and manipulandum) when the reward cue (discriminative stimulus positively correlated with positive reinforcement) is located at the response manipulandum (object that when contacted or manipulated defines the performance of the instrumental response). Evidence reviewed shows that CAM induces excessive and compulsive instrumental responding relative to otherwise comparable non-CAM control procedures. In humans, symptoms of drug abuse are particularly likely when the drug-taking implement (response manipulandum at which instrumental drug-taking is directed) is also predictive of the drug's rewarding effects (reward cue). Evidence that the predictive relationship between a drug-taking implement and drug reward relates to drug abuse is reviewed, and implications for treatment and prevention are considered. CAM is related to neurobiological models of drug abuse that emphasize the role of the neurotransmitter dopamine (DA). CAM produces convergence of DA-mediated responding for conditioned reinforcement with DA mediation of psychomotor activation and incentive-motivational processes to yield reflexive cue-directed responding not observed in non-CAM controls.

Animals↗
PubMed1991

Peak shift revisited: a test of alternative interpretations.

In Experiment 1, 2 groups of human subjects were trained to respond to 1 of 2 light intensity stimuli, S2 or S4, and then were tested for generalization with a randomized series of increasing values from S1 to S11. Both groups, including the group trained to respond to dimmer value, showed peak shifts to a brighter more centrally located test stimulus. In Experiment 2, which used line angle stimuli, both the size of the difference between S+ and S- and the range of test stimuli that extended beyond S+ were varied. The larger the S(+)-S- separation and the larger the range, the greater was the peak shift obtained. In Experiment 3, training involved an S- (line angle) surrounded by 2 S+ values with testing symmetrical about the training values and covering either a narrow or a wide range. The wide range produced greater peak shifts in both directions from S-. All 3 experiments support an adaptation-level interpretation of intradimensional discrimination learning and generalization test performance in human subjects. Related work with animals suggests the presence of similar processes.

Adult↗
PubMed1976

An assessment of hypothesis testing in mentally retarded adolescents.

Groups of educable and trainable institutionalised retarded adolescents were tested on a discrimination learning problem with a modified blank trials procedure in an attempt to measure their hierarchy of hypotheses. Results indicated that the hierarchy and size of initial hypothesis sets varied as a function of degree of retardation. Trainable retarded subjects had fewer hypotheses, and initially chose position hypotheses predominantly. Under discriminate reinforcement, most of these were readily switched to stimulus dimension hypotheses, which they retained during additional non-discriminate (100 per cent) reinforcement trials. Educable retarded subjects predominantly chose stimulus dimension hypotheses initially, and most of these switched to position hypotheses during either discriminate or non-discriminate reinforcement trials.

Adolescent↗
PubMed1997

Effects of sodium azide on motor activity, motor coordination, and learning.

Because of the proposed importance of cytochrome oxidase in some neurological disorders, an inhibitor of this enzyme was evaluated in a battery of tests measuring exploration, motor coordination, and learning. Mice injected with sodium azide (6 or 12 mg/kg) were slower to initiate a response in a T maze and had less rears in a small chamber than mice injected with placebo. Drugged mice did not alternate spontaneously even at a minimal retention interval (0 min), but were not impaired in water maze spatial and visual discrimination learning tasks. No group differences emerged in terms of horizontal motor activity and its habituation, number of grooming episodes, and motor coordination. These results indicate that azide-induced slowing of motor activity is situation-specific and is accompanied by abnormalities in choice behavior in a T maze.

Animals↗
PubMed1994

[Transplacental neurotoxic effects of monosodium glutamate on structures and functions of specific brain areas of filial mice].

Monosodium glutamate (MSG) was shown to penetrate placental barrier and distribute almost evenly among embryonic tissues using 3H-Glu as a tracer. When a lower (1.0 mg/g) and a higher (2.5 mg/g) doses of MSG were alternatively injected to Kunming maternal mice in every other days from mating to deliveries, obvious injury occurred in the ability of memory retention and Y-maze discrimination learning of adult filial mice pregnantly treated with higher doses (2.5 mg/g) of MSG. Meanwhile, the neuronal damages were observed in not only arcuate nucleus but also ventromedial nucleus of hypothalamus. Characteristic cytopathological changes induced by MSG showed swollen cytoplasm, dark pyknotic nuclei and loss of neurons. The radioligand-bindings in both hippocampus and hypothalamus altered significantly after the pregnant treatment of MSG. Possible mechanisms underlying MSG excitotoxic phenomena studied in single neuron by use of Ca2+ sensitive indicator Fura-2 with Spex AR-CM-MIC Cation Measurement System, might be due to increases of intracellular free Ca2+ concentration induced by MSG exposure, which was related to both the influx of Ca2+ and the depletion of Ca2+ from the intracellular Ca2+ stores. These experimental findings indicated that MSG performed its transplacental neurotoxicity in a dose-dependent manner. The excessive activation of Glu receptors and the overloading of intracellular Ca2+ induced by MSG ultimately leading to neuronal death may result in the reduction of the capability of learning and memory in adult filial mice pregnantly treated with MSG.

Animals↗
PubMed1983

The effects of postnatal anoxia on behaviour and on the muscarinic and beta-adrenergic receptors in the hippocampus of the developing rat.

Exposure of rats to 25 min anoxia within 24 h following birth caused behavioural as well as biochemical changes during their development and maturity. Following postnatal anoxia, a significant increase in the concentration of the cholinergic muscarinic receptors in the hippocampus was noted at the early stages of development, between 6 and 20 days of age, but reached normal values at 40 days of age. However, at this age, significant increase in the concentration of beta-adrenergic receptors in the hippocampus was found, which remained significantly high during maturity and adulthood, as compared to controls. Rats submitted postnatally to anoxia exhibited hyperactivity in the open field which was maximal at 20-25 days of age and declined towards normal values at 40 days of age. At maturity, between 60 and 80 days of age, these rats showed poor performance in a complex 6-choice discrimination learning but not in simple differential conditioning. Possible correlations between the behavioural and biochemical findings are discussed.

Animals↗
PubMed1995

Age and dose-related effects of hippocampal ibotenic acid on lesion size, mortality, and nonspatial working memory in infant rats.

Three experiments are presented in which the neural and behavioral consequences of multiple ibotenic acid (IBO) injections into the hippocampus were examined in Sprague-Dawley rat pups. Rat pups were 11 or 15 days of age at the time of surgery (SURG11, SURG15), the dose of IBO was either 1 microgram in 1 microliter, 2.5 micrograms in 0.5 microliters, or 5 micrograms in 1 microliter for each of four injections, and pups were allowed to survive for 3 or 7 days after the lesion was made. The Fink-Heimer silver stain was used in Experiment 1 to examine the extent of neural damage following unilateral lesions and showed that the degeneration was primarily located in the hippocampus. The magnitude of the damage was greatest in younger pups and in those which received the higher of the two concentrations (injection volume was not a factor). Degenerating fibers were seen in the columns of the fornix as well as precommissural fornix fibers, but only in SURG15 animals when damage extended into the dorsal subiculum. Mortality rates following multiple IBO injections were very high in infant rats, in some cases as high as 60%. Experiments 2 and 3 examined the effects of bilateral lesions on neuroanatomy and behavior. Bilateral lesions were somewhat smaller than unilateral lesions, and as for unilateral lesions, degeneration in pre- and postcommissural fornix was seen only in SURG15 animals. The behavioral task used in Experiments 2 and 3 was patterned single alteration, a memory-based appetitive learning discrimination. Earlier work has shown that damage to the infant hippocampus results in moderate deficits in this task at 30-s intervals and more substantial deficits at 60-s intertrial intervals. This was not the case in the present studies: regardless of age at surgery or time postlesion, all infant rats tested learned this discrimination at the two intertrial intervals. As has been recently reported for adult rats, excitotoxic lesions of the hippocampus in infant rats do not produce the same patterns of behavioral deficits as electrolytic lesions.

Age Factors↗
PubMed2005

Hippocalcin-deficient mice display a defect in cAMP response element-binding protein activation associated with impaired spatial and associative memory.

Hippocalcin is a member of the neuronal calcium sensor (NCS) protein family that is highly expressed in hippocampal pyramidal cells and moderately expressed in the neurons of cerebral cortex, cerebellum and striatum. Here we examined the physiological roles of hippocalcin using targeted gene disruption. Hippocalcin-deficient (-/-) mice displayed no obvious structural abnormalities in the brain including hippocampal formation at the light microscopic level. Deletion of hippocalcin did not result in up-regulation of the hippocalcin-related proteins; neural visinin-like Ca(2+)-binding proteins (NVP) 1, 2, and 3. The synaptic excitability of hippocampal CA1 neurons appeared to be normal, as estimated by the shape of field excitatory postsynaptic potentials elicited by single- and paired-pulse stimuli, and by tetanic stimulation. However, N-methyl-d-aspartate stimulation- and depolarization-induced phosphorylation of cAMP-response element-binding protein (CREB) was significantly attenuated in -/- hippocampal neurons, suggesting an impairment in an activity-dependent gene expression cascade. In the Morris water maze test, the performance of -/- mice was comparable to that of wild-type littermates except in the probe test, where -/- mice crossed the previous location of the platform significantly less often than +/+ mice. Hippocalcin-deficient mice were also impaired on a discrimination learning task in which they needed to respond to a lamp illuminated on the left or right side to obtain food reinforcement. No abnormalities were observed in motor activity, anxiety behavior, or fear learning. These results suggest that hippocalcin plays a crucial role in the Ca(2+)-signaling pathway that underlies long-lasting neural plasticity and that leads to spatial and associative memory.

Animals↗
PubMed1972

Some features of the dorsolateral frontal and inferotemporal syndromes in monkeys.

Our frontal- and temporal-lobe experiments to date support the following conclusions. Anterior temporal or inferotemporal lesions affect object learning set retention, and older work dealing with this task has indicated that temporal ablations, at the very least, retard initial acquisition of the set. Inferotemporal monkeys may lose object sets and yet have no deficits in either the learning or short-term retention of single visual habits. Their well-known impairments in visual pattern learning are products of background-cue learning which become most marked in test situations which bias their responses to these cues. Their pattern-learning deficit is an accentuation of a normal characteristic of the monkey, and implies no profound qualitative alteration of the way that they perceive stimuli. Our work that has dealt with frontal preparations indicates that Jacobsen's effect can be produced either by proactive interference or by difficulties in attending. The latter are probably compensable if lesions are produced in very early infancy, but data from experiments with cats has suggested that perseverative interferences are not. Perseverative tendencies can be suppressed with practice in discrimination learning situations, but the tendencies can then be fully reinstated by relatively minor distractions. Frontal-lobe lesions have almost no effects upon object learning set formation, nor do they have important effects upon a monkey's short-term retention of a habit.

Animals↗
PubMed1982

Differences in Y-maze retention of rats: selection according to open field activity.

Adult male Wistar rats of a heterogeneous outbred population were selected according to their open field ambulation and classified into two groups: animals showing the most activity during the first 2 min (A, fast habituation), or after the first 2 min (B, delayed habituation) of a 10 min observation period. One week later these rats were tested for foot-shock motivated brightness discrimination learning and retention in a Y-maze. It was found that group A rats exhibited higher %-savings than group B rats, whereas their learning performance was not different. Thus, our results show that rats differing in their Y-maze retention ability can be selected on the basis of certain open field measures.

Animals↗
PubMed2006

Adolescent fluoxetine exposure produces enduring, sex-specific alterations of visual discrimination and attention in rats.

Over the past two decades the use of selective serotonin reuptake inhibitors (SSRIs) to treat behavioral disorders in children has grown rapidly, despite little evidence regarding the safety and efficacy of these drugs for use in children. Utilizing a rat model, this study investigated whether post-weaning exposure to a prototype SSRI, fluoxetine (FLX), influenced performance on visual tasks designed to measure discrimination learning, sustained attention, inhibitory control, and reaction time. Additionally, sex differences in response to varying doses of fluoxetine were examined. In Experiment 1, female rats were administered (P.O.) fluoxetine (10 mg/kg ) or vehicle (apple juice) from PND 25 thru PND 49. After a 14 day washout period, subjects were trained to perform a simultaneous visual discrimination task. Subjects were then tested for 20 sessions on a visual attention task that consisted of varied stimulus delays (0, 3, 6, or 9 s) and cue durations (200, 400, or 700 ms). In Experiment 2, both male and female Long-Evans rats (24 F, 24 M) were administered fluoxetine (0, 5, 10, or 15 mg/kg) then tested in the same visual tasks used in Experiment 1, with the addition of open-field and elevated plus-maze testing. Few FLX-related differences were seen in the visual discrimination, open field, or plus-maze tasks. However, results from the visual attention task indicated a dose-dependent reduction in the performance of fluoxetine-treated males, whereas fluoxetine-treated females tended to improve over baseline. These findings indicate that enduring, behaviorally-relevant alterations of the CNS can occur following pharmacological manipulation of the serotonin system during postnatal development.

Age Factors↗
PubMed1975

Learned helplessness, depression, and anxiety.

The learned helplessness model of depression predicts that depressives should tend to perceive reinforcement as response-independent in skill tasks. Depressed-anxious, nondepressed-anxious, and nondepressed-nonanxious college students estimated their chances for success in a skill or a chance task. (Virtually no depressed-nonanxious subjects could be obtained.) Depressed-anxious subjects showed less expectancy change in skill than nondepressed-anxious subjects, while these two groups exhibited similar expectancy change in chance. Nondepressed-anxious and nondepressed-nonanxious subjects did not differ in either skill or chance. The results for a discrimination learning problem were mixed. The groups did not differ in latency to shut off an aversive noise. So, depressed subjects perceptually distort the outcomes of skilled responding as being response-independent, and they may, under certain conditions, show deficits at learning the consequences of responses. These deficits may reflect learned helplessness and are specific to depression.

Anxiety↗
PubMed1991

Hemispheric asymmetries in visual pattern processing in infancy.

A right hemisphere advantage was observed in a previous study of 4- to 9-month old infants presented with a face discrimination task (de Schonen & Mathivet, 1990). The present study was designed to investigate pattern processing by the two hemispheres and the interhemispheric communication of this processing. Infants aged 4 to 9 months were tested with divided visual field presentations in one or two discrimination tasks. Under both task conditions, the infants had to discriminate between two patterns in which only two local components differed. Under one condition the components of the patterns were arranged so as to produce a face-like pattern. Under the other condition the same components were arranged into arbitrary patterns that were not "good form" patterns. No performance asymmetry was observed with the arbitrary patterns; whereas, a right hemisphere (RH) disadvantage was observed with the face-like patterns compared with both the RH performances on the arbitary patterns and the left hemisphere (LH) performances on the face-like patterns. These results show that the RH advantage for individual face recognition is not due to a general immaturity or inability of the LH in pattern processing at this period of development, nor to a more specific inability in a local mode of pattern processing. On the other hand, the RH does not completely lack local processing capacity, but is at a disadvantage when this local mode of processing has to be used with face-like (or good form) patterns. The interhemispheric communication of visual discrimination learning was tested by measuring learning transfer between the visual fields. Contrary to de Schonen and Bry's study (1987) on faceness recognition, no data in favor of interhemispheric communication were recorded in the present study.

Attention↗