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 1,585 records · Page 88Linked to original sources
PubMed1994

Perception of odor mixtures by the spiny lobster Panulirus argus.

We used spiny lobsters (Panulirus argus) in a discrimination learning procedure with aversive conditioning to examine their behavioral discrimination of adenosine-5'-monophosphate (AMP), betaine, L-cysteine and their binary mixtures. Our results show that spiny lobsters can clearly discriminate among binary mixtures and their components. Lobsters aversively conditioned to avoid responding to a binary mixture continued to respond to that mixture's components, and lobsters that were aversively conditioned to avoid responding to a compound tended to continue to respond to binary mixtures containing that compound. Thus, responses of conditioned lobsters to binary mixtures were not usually intermediate between the responses to the mixtures' components, which might be expected for response-matched compounds. This result might arise from any of several factors. First, it might result from mixture interactions in the peripheral olfactory system, if the responses of olfactory receptor neurons to one component of a binary mixture were suppressed by the other component, making the response to the mixture more similar to the suppressing component. Electrophysiological data from a population of 50 singly-recorded olfactory receptor neurons (Daniel and Derby, 1994) do not consistently support this idea. A second possible reason for the behavioral response to a binary mixture not being intermediate between the responses to its components involves higher order processing, such as mixture interactions generated in olfactory interneurons in the CNS (which is known to occur: Derby et al., 1985; Ache, 1989), configural learning or associative processing.

Adenosine Monophosphate↗
PubMed2001

Calcium channel antagonists enhance retention of passive avoidance and maze learning in mice.

Although a number of studies have shown that treatment with calcium channel antagonists (CCAs) can ameliorate impairments in learning and memory in aged animals, evidence for a general nootropic effect of CCAs in neurologically normal young adult animals is ambiguous. This study attempts to resolve some of this ambiguity by comparing the effects of several CCAs on retention of passive avoidance learning and acquisition and retention of appetitively motivated spatial discrimination learning in young adult mice. Animals were trained in a step through passive avoidance apparatus and, immediately after training, injected subcutaneously with different doses of nimodipine, nifedipine, amlodipine, flunarazine, diltiazem, or verapamil. Retention was tested 24 h after training. In the maze-learning task mice were treated with the same doses of the aforementioned CCAs immediately after a brief training session in a linear maze and retention was tested 24 h after training. The most effective dose of each agent in the maze-retention experiment was administered to additional groups of animals 1 h prior to training to determine the effects of CCAs on acquisition processes. The effects of central administration of CCAs were examined by intracerebroventricular injection of different doses of amlodipine immediately after passive avoidance training. Results showed (1) all peripherally administered drugs except verapamil facilitated retention of passive avoidance training in a dose-dependent manner, (2) all drugs dose dependently facilitated retention of linear maze learning, (3) all doses of the drugs (except verapamil) which facilitated maze retention also facilitated maze learning, and (4) central administration of the dihydropyridine amlodipine produced a dose-dependent facilitation of the retention of passive avoidance learning. These data indicate that drugs which block calcium channels can enhance retention of two different types of learning in mice.

Animals↗
PubMed1989

The effects of fornix transection and combined fornix transection, mammillary body lesions and hippocampal ablations on object-pair association memory in the rhesus monkey.

Cynomolgus monkeys were tested on an associative memory task in which they had to remember object-object pairings. Eight animals (4 unoperated monkeys and 4 monkeys with lesions to components of the 'hippocampal-mammillary' circuit) were trained initially on a conditional object-pair association task that was similar to simple discrimination learning, but which involved presentation of object-pairs instead of single objects. Object-pairs were made up from 4 different objects, each with an identical copy. Animals had to learn which pairings of the 4 objects were rewarded (e.g. AB or CD) and which pairings were not (e.g. AC or BD). Objects appeared as a member of both rewarded and non-rewarded pairs. After several stages of training all monkeys reached a high level of performance making greater than 90% correct choices. In a performance test the monkeys had to discriminate between 3 single objects depending on their past associations with the other objects. Animals had to choose the two objects which in initial training were rewarded as an object pair. Monkeys with the 'hippocampal-mammillary' circuit lesions learned the initial object-pair discriminations at the same rate as control monkeys. In the performance test, however, monkeys with the 'hippocampal-mammillary' circuit lesions performed at chance levels, whereas the control monkeys performed significantly better. The results demonstrate a dissociation between the 'habit' and 'mediational' memory systems for ostensibly the same object-pair associations. They also indicate an important contribution of the 'hippocampal-mammillary' circuit in nonspatial association memory.

Animals↗
PubMed1994

[Is there a feature-positive effect in classical conditioning in humans?].

Jenkins and Sainsbury (1969, 1979) first described an asymmetry in pigeon's operant discrimination learning which they called a feature-positive effect. Subsequent studies demonstrated that other animals as well as humans also show a similar asymmetry. The effect is often explained as being caused by a bias in information processing which results from the neglect of negative information as a discriminative cue. The effect has also been observed in classical conditioning experiments, but not yet with human subjects. Sometimes, however, a reversal of the asymmetry, i.e., a feature-negative effect, has been observed. The experiment reported here primarily intended to demonstrate a feature-positive effect in a classical conditioning procedure with human subjects. Secondly, we also wanted to test an alternative explanation of the feature-positive effect. We found that a substantial feature-positive effect does indeed occur during classical conditioning in human subjects. Our results, however, did not fully support the alternative explanation based on rule learning.

Adult↗
PubMed1993

Learning deficits in lab-reared cats.

Data obtained by the author and his colleagues on deficits in learning in cats reared in the lab breeding colony are reviewed. As compared with cats who lived free in a farm during the first 3-4 months of life, the lab-reared cats showed a dramatic impairment of delayed response learning to visual and auditory stimuli. They also showed some impairment of visual discrimination learning: they commited more errors than farm-reared cats when a discrimination apparatus had a partition between the stimuli, their reaction times were longer, and after lesions of the superior colliculus-pretectum complex their relearning was impaired. Thus, even moderate impoverishment of environment can considerably affect later learning ability.

Animal Husbandry↗
PubMed1988

Inescapable shock and attention to internal versus external cues in a water discrimination escape task.

In these experiments we examined discrimination learning in a water escape task following exposure to escapable, yoked inescapable, or no electric shock. Inescapable shock did not have an effect on swim speeds in any of the experiments. Inescapable shock interfered with the acquisition of a position (left-right) discrimination when an irrelevant brightness cue (black and white stimuli) was present. However, inescapable shock did not affect the acquisition of the position discrimination when the irrelevant brightness cue was removed. Inescapably shocked subjects showed facilitated learning relative to escapably shocked and nonshocked subjects when the brightness cue was included as a relevant cue. These data may resolve discrepancies between studies that did, and did not, find inescapable shock to interfere with the acquisition of discriminations. Moreover, they point to attentional processes as one locus of the cognitive changes produced by inescapable shock and suggest that exposure to inescapable shock biases attention away from "internal" response-related cues toward "external" cues.

Animals↗
PubMed2004

A novel cognitive palatability assessment protocol for dogs.

Assessment of canine palatability is important for both the pet food and pharmaceutical industries; however, the current palatability assessment protocols are limited in their utility. The most common technique, the two-pan test, does not control for the satiating effects of food and may not be useful for long-term palatability analysis because nutritional or caloric characteristics of the diets may interfere with the results. Furthermore, the large quantities of foods consumed may be detrimental to the health of animals that do not self-limit their food intake. The purpose of this study was to determine whether a cognitive protocol could be used to determine food palatability in dogs. Five beagle dogs were trained on a three-choice object-discrimination learning task. After establishing object preferences, the preferred object was associated with no reward, a second object was associated with the dog's normal laboratory diet (Purina Agribrands Canine Lab Chow No. 5006; Agribrands Purina Canada, Inc., Woodstock, ON, Canada), and the third object was associated with a commercial (Hill's P/D; Hill's Pet Nutrition Inc., Topeka, KS) diet. In the discrimination-training phase, dogs were trained until they learned to avoid the no-reward object. They were subsequently given an additional 20 test sessions, which were used to determine food preference. In the reversal phase, which involved reversal learning, the object-food associations were modified, such that the object that was previously associated with Hill's P/D diet was now associated with the normal laboratory diet and vice versa. Once the dogs learned to avoid the no-reward object, they were tested for an additional 20 sessions. All subjects learned to avoid the no-reward object during the initial learning, and the number of choices to the object associated with the Hill's P/D diet was greater than the number of choices to the objects associated with the dry laboratory diet (P < 0.05) and no reward (P < 0.05), indicating a strong preference for the Hill's P/D diet. The object preferences were reversed in only three of five dogs when the food-choice associations were reversed, although the two phases did not differ significantly from one another. The protocol in the present study provides a robust measure of food palatability and circumvents many of the limitations associated with other palatability assessment techniques. The present protocol should be useful as a replacement or adjunct to other tests of palatability, but requires further validation by comparing the assessment of more similar and novel foods directly with other palatability tests.

Animal Feed↗
PubMedDate not supplied

Contextual and serial discriminations: a new learning paradigm to assess simultaneously the effects of acute stress on retrieval of flexible or stable information in mice.

The present study was aimed at simultaneously determining on the same subject, the effects of stress on retrieval of flexible (contextual or temporal) or stable (spatial) information. Three behavioral paradigms carried out in a four-hole board were designed as follows: (1) Simple Discrimination (SD), in which mice learned a single discrimination; (2) Contextual and Serial Discriminations (CSD), in which mice learned two successive discriminations on two different internal contexts; (3) Spatial Serial Discriminations (SSD), in which mice learned two successive discriminations on an identical internal context. The stressor (three inescapable electric footshocks) was delivered 5 min before retention, occurring 5 min or 24 h after acquisition. Results showed that this stressor increased plasmatic corticosterone levels and fear reactivity in an elevated-plus-maze, as compared with nonstressed mice. The stressor reversed the normal pattern of retrieval observed in nonstressed controls in the CSD task, this effect being context dependent, as it was not observed in the SSD task. Overall, our study shows that stress affected the retrieval of flexible and old information, but spared the retrieval of stable or recent ones. Therefore, these behavioral paradigms allow us to study simultaneously, on the same animal, the effects of stress on distinct forms of memory retrieval.

Acute Disease↗
PubMed2006

Thalamic-prefrontal cortical-ventral striatal circuitry mediates dissociable components of strategy set shifting.

The mediodorsal nuclei of thalamus (MD), prefrontal cortex (PFC), and nucleus accumbens core (NAc) form an interconnected network that may work together to subserve certain forms of behavioral flexibility. The present study investigated the functional interactions between these regions during performance of a cross-maze-based strategy set-shifting task. In Experiment 1, reversible bilateral inactivation of the MD via infusions of bupivacaine did not impair simple discrimination learning, but did disrupt shifting from response to visual cue discrimination strategy, and vice versa. This impairment was due to an increase in perseverative errors. In Experiment 2, asymmetrical disconnection inactivations of the MD on one side of the brain and PFC on the other also caused a perseverative deficit when rats were required to shift from a response to a visual cue discrimination strategy, as did disconnections between the PFC and the NAc. However, inactivation of the MD on one side of the brain and the NAc contralaterally resulted in a selective increase in never-reinforced errors, suggesting this pathway is important for eliminating inappropriate strategies during set shifting. These data indicate that set shifting is mediated by a distributed neural circuit, with separate neural pathways contributing dissociable components to this type of behavioral flexibility.

Animals↗
PubMedDate not supplied

The effects of prenatal exposure to methylmercury on aggressive behavior in the rat.

The sensitivity of isolation-induced aggressive behavior to prenatal treatment of 6.0 mg/kg methylmercuric chloride (MMCl) by gavage on gestation days 6-9 was assessed in a subset of animals from the Collaborative Behavioral Teratology Study (CBTS). CBTS behavioral measures consisted of negative geotaxis, olfactory discrimination, auditory startle habituation, 1-hr activity, 23-hr activity, activity following pharmacological challenge and visual discrimination learning. Auditory startle was the only CBTS behavioral measure that discriminated among prenatal treatment groups. MMCl animals also were reliably more aggressive than vehicle controls in dyadic encounters. The results suggest that tests of aggressive behavior, which rarely have been included in teratologic assessments, be considered in the formulation of behavioral screening paradigms. The advantages of including tests of aggression and the relationship between aggressive and startle responses are discussed.

Acoustic Stimulation↗
PubMedDate not supplied

[Behavioral and neuronal effects of visual deprivation in cats].

Recent data obtained in the Nencki Institute are reviewed. In the cats deprived of pattern vision from birth several deficits were observed: (I) A simultaneous object discrimination learning for food reward was strongly impaired. However, retention of discrimination was only slightly impaired by bisual cortex ablation. (II) Ocular following reflex was impaired. (III) In the living cages stereotyped behavior appeared. (IV) Direction selectivity of superior colliculus units was impaired. (V) Percentage distribution of insoluble proteins in the electrophoretic pattern from visual and somatic sensory cortex was affected.

Animals↗
PubMed1981

The effect of chronic diazepam treatment on discrimination performance and 3H-flunitrazepam binding in the brains of shocked and nonshocked rats.

The purpose of the present study was: (1) to investigate the effects of unavoidable shock on an appetitively motivated discrimination task; (2) to evaluate the effect of chronic diazepam treatment on the performance of a previously learned discrimination task in shocked and nonshocked animals; (3) to measure the binding of 3H-flunitrazepam (an analogue of diazepam) to selected brain regions of chronically diazepam-treated shocked and nonshocked rats, in comparison to saline-treated controls. Results indicated that unavoidable shock significantly interfered with the learning of a new, nonshock-related discrimination task. The effect of chronic diazepam treatment on the performance depended on the previous experience of the animal; chronic diazepam treatment significantly improved the maze performance of shocked animals. On the other hand, chronic diazepam treatment in the nonshocked animals tended to interfere with the performance of the discrimination task. Neurochemical data showed significant reduction in 3H-flunitrazepam binding to diazepam receptors in membranes from the brains of a nonshocked diazepam-treated (CD) group in comparison to a nonshocked saline-treated (CS) group. In contrast, the unavoidable shock-treated diazepam group (SD) showed opposite effects, the binding of 3H-flunitrazepam increasing significantly. A significant increase in the maximal binding sites in the frontal cortex from shocked rats treated with diazepam, compared to the nonshocked diazepam-treated rats, was detected by Scatchard analysis.

Animals↗
PubMed1983

Neuropsychological assessment of learning disabilities: a discriminant analysis.

The neuropsychological test scores of 23 learning disabled children were compared with those of a matched population of normal children in the 9-1 to 13-1 age range. All children were administered the Wechsler Intelligence Scale for Children-Revised (WISC-R), a dichotic listening task involving both free and directed recall conditions, a handedness inventory, the Tactile Performance Test and the Category Test from the Halstead-Reitan Neuropsychological Test Battery. A multivariate analysis of variance resulted in a significant separation between groups (p less than .001) using these procedures. A stepwise discriminant function analysis revealed that both of the directed dichotic tasks contributed the most of all 13 measures to the significant group separation. In addition, other cognitive tasks found to discriminate normal from learning disabled children include general verbal processes, concept formation, and tactile memory. These findings suggest that the directed dichotic listening procedure and the WISC-R Verbal IQ measure are reasonably valuable clinical tools in the classification of learning disabilities.

Adolescent↗
PubMed1985

Analysis of appetitive motivation in preweanling rats: application of bromocryptine mesylate.

Two experiments investigated discrimination learning with preweanling rats (Rattus norvegicus) following different experimental deprivation treatments. In Experiment 1, 10- to 11-day-old Sprague-Dawley rats were deprived for 24 h of either nutrients and maternal contact through placement in an incubator or only nutrients by placement in the nest of a bromocryptine mesylate-treated dam. Bromocryptine mesylate inhibits prolactin release and thereby prevents lactation with only minimal effect on maternal behaviors. After the deprivation period, pups were trained to perform a spatial discrimination for milk infusion into the oral cavity or for the opportunity to suckle the dry nipples of an anesthetized dam. The results revealed, irrespective of deprivation treatment, that pups failed to acquire a simple T-maze spatial discrimination for milk reward although they rapidly learned to approach and locate an anesthetized dam to suckle. Experiment 2 followed up with a different procedure. Results indicated that during bouts of suckling rat pups preferred an active, lactating dam letting down milk to an identical dam not letting down milk due to her pretreatment with bromocryptine mesylate. These results illustrate a constraint on learning which affects immature rats. The capability to learn on appetitively motivated spatial discrimination appears intricately tied to the context in which training occurs. Results are discussed according to how the organism's expectancy can mediate performance.

Animals↗
PubMed1989

Nitrate induced changes in sensoro-motor development and learning behaviour in rats.

Development of sensoro-motor functions and adult learning behaviour was studied in rats subjected to nitrate exposure. Pregnant and lactating dams and their offspring were supplied with drinking water containing nitrate, 1.12 or 2.24 mM KNO3, and compared with nitrate-free controls. Postnatal maturation of reflexes, that of sensory and somatic parameters and motor activity, furthermore, the acquisition of one-way avoidance and rewarded discriminative learning behaviour in adulthood were examined. Reflexes (righting, cliff-avoidance) and hearing startle reaction maturated earlier in nitrate treated groups. No difference was found in olfactory homing behaviour, in the time of eye opening and in body weight growth. Open-field motor activity was higher at days 5, 7, 10 after birth, but hypoactivity ensued after day 20. A marked learning deficit was observed both in punished and in rewarded learning paradigms. The results indicate a nitrate induced deviation in behavioural development, and an impairment in learning behaviour, particularly of discriminative type.

Animals↗
PubMedDate not supplied

Selective impairment of learning and blockade of long-term potentiation by an N-methyl-D-aspartate receptor antagonist, AP5.

Recent work has shown that the hippocampus contains a class of receptors for the excitatory amino acid glutamate that are activated by N-methyl-D-aspartate (NMDA) and that exhibit a peculiar dependency on membrane voltage in becoming active only on depolarization. Blockade of these sites with the drug aminophosphonovaleric acid (AP5) does not detectably affect synaptic transmission in the hippocampus, but prevents the induction of hippocampal long-term potentiation (LTP) following brief high-frequency stimulation. We now report that chronic intraventricular infusion of D,L-AP5 causes a selective impairment of place learning, which is highly sensitive to hippocampal damage, without affecting visual discrimination learning, which is not. The L-isomer of AP5 did not produce behavioural effects. AP5 treatment also suppressed LTP in vivo. These results suggest that NMDA receptors are involved in spatial learning, and add support to the hypothesis that LTP is involved in some, but not all, forms of learning.

2-Amino-5-phosphonovalerate↗
PubMed1981

Effects of training on response latency and accuracy for a difficult visual discrimination.

The learning of a difficult discrimination task was investigated in a laboratory simulation of a quality control task. In an earlier experiment, observers were trained to discriminate between 2 brief, masked stimulus patterns. Then, a trained and an untrained group of observers were tested on the same stimulus-discrimination task. Response latency as well as P(Dis) were measured in a forced-choice reaction time paradigm. Untrained observers responded with a mean probability of correct discrimination, P(Dis), = .65 for stimuli with 30-msec. duration and mean P(Dis) greater than or equal to .90 those stimuli with 100-msec. duration. Trained observers produced discrimination scores of P(Dis) greater than or equal to .90 for all stimulus durations tested. Despite this large, reliable training effect of P(Dis), response latencies did not differ reliably between the two groups but instead were a negative function of stimulus duration for both trained and untrained observers.

Discrimination Learning↗