Stimulus-characteristics and rate of learning visual discriminations by experimentally naive monkeys.
Explore the source record for details and available documents.
Animals↗
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.
Cholinergic blockade in the rat impairs strategy selection but not learning and retention of nonspatial visual discrimination problems in a swimming pool.
A procedure was developed to study black versus white and horizontal versus vertical pattern visual discriminations in a swimming pool. The effects of central cholinergic muscarinic receptor blockade by atropine sulfate was then evaluated. The drug treatment impaired acquisition but not retention. Behavioral observations showed that the control rats used a number of strategies during the process of problem solving that facilitated acquisition of the discrimination. Through modifications of training procedures, the processes of strategy selection and discrimination learning were dissociated. Cholinergic blockade was found to impair strategy selection but not discrimination learning. The results question the widely held view that cholinergic systems are involved in learning and memory and suggest instead that cholinergic systems are involved in the selection of the movements or strategies that are prerequisite for learning.
Animals↗
Effects of a novel fentanyl derivative on drug discrimination and learning in rhesus monkeys.
Three monkeys discriminated 1.78 mg/kg of mirfentanil while responding under a fixed-ratio 5 schedule of stimulus-shock termination. Two mirfentanil derivatives, OHM3295 and OHM10579, substituted for mirfentanil in all subjects. However, other drugs produced variable effects among monkeys; for example, mu and kappa opioid agonists and clonidine substituted for mirfentanil on some occasions in two monkeys. Cocaine, amphetamine, and ketamine did not substitute in any subject. Opioid antagonists did not attenuate the effects of mirfentanil. In monkeys responding under a repeated acquisition and performance procedure, errors increased only during the acquisition phase at doses of mirfentanil that decreased response rates. Thus, unlike fentanyl, the discriminative stimulus effects of mirfentanil do not appear to be mediated exclusively through opioid receptors. Finally, mirfentanil does not appear to disrupt complex behavioral processes.
Analgesics, Opioid↗
Learning to discriminate the sex of conspecifics in male Japanese quail (Coturnix coturnix japonica): tests of "biological constraints".
Male Japanese quail learn to approach and remain near female, but not male, quail if they are allowed to copulate with female quail and receive noncopulatory exposures to males. The generality of the mechanisms involved in this type of discrimination learning was investigated in the present study. In Experiment 1, Ss learned to spend more time near initially unfamiliar blonde quail than familiar brown female or male quail as a result of being allowed to copulate with the blonde, but not the brown, quail. In Experiment 2, Ss learned to respond more to nonreproductive male as compared with female quail as a result of being allowed to copulate with the males, but not with the females. The experiments provided some evidence of a bias favoring responding to females independent of copulatory reinforcement contingencies. However, the results also indicated remarkable plasticity of discrimination learning about species-specific sexual stimuli.
Animals↗
Hippocampal and nonhippocampal contributions to place learning in rats.
Brain structures thought to be critical for learning and memory were lesioned, and the effects on rats' ability to locate food on a radial maze in situations that provided different types of information was used to suggest general principles of information processing by hypothesized neural systems that include each of the lesioned structures. When animals were confined to food-containing and empty arms on different training trials, the learned discrimination between the arms was amygdala based. More training trials were required for ambiguous (adjacent arms) than for unambiguous (widely separated arms) discriminations. When rats moved around and entered both food and no-food arms on the same trial, the unambiguous discrimination was learned by both dorsal striatum- and hippocampus-based systems; however, the ambiguous discrimination was learned only by the hippocampus system.
Amygdala↗
Symbolic matching by pigeons: rate of learning complex discriminations predicted from simple discriminations.
Pigeons had no greater difficulty learning a complex discrimination involving arbitrary among stimuli (symbolic matching) than one involving interrelations based on stimulus similarity (matching-to-sample). The relative rates of acquisitions of matching and symblic matching may be accounted for by the discriminability between sample stimuli and between comparison stimuli, with the former playing the more important role.
Animals↗
Multicomponent procedure to teach conditional discriminations to children with autism.
Five children with autism with a history of failing to acquire conditional discriminations learned to discriminate objects in response to spoken names or to match amounts to numbers with a combined blocking procedure. The procedure for teaching object discriminations involved (a) presenting the same spoken word until 10 consecutive correct responses occurred and (b) keeping the left-right location of the objects on the table constant. After mastery, the requirement for changing the spoken word was gradually reduced. Finally, the spoken words were presented randomly. In the final stage, the objects were located randomly. The procedure to teach number matching was similar. All children learned these discriminations with few errors. This procedure may be beneficial in teaching conditional discriminations to children with learning difficulties.
Autistic Disorder↗
Learning motion discrimination with suppressed MT.
We studied perceptual learning in motion discrimination when the brain's middle temporal area (MT/V5) was functionally suppressed. This was achieved by using the "paired-dots" motion stimulus where the two dots in a pair always move in counter-phase over a short distance [J. Neurosci. 14 (1994) 7357]. The motion directional signal of the stimulus is therefore always 0 on average. As a result, this stimulus activates MT in Rhesus monkeys no more than flicker noise does [J. Neurosci. 14 (1994) 7367]. We added a new manipulation to eliminate the Glass pattern in the original stimulus that would have otherwise provided a static orientation cue. Two such new motion stimuli were presented sequentially, in a 2AFC task. Subjects decided if the global motion-axis of the stimuli changed clockwise or counter-clockwise. When the task difficulty was set at 60% correct, none of the subjects could learn with feedback, even though their performance was well above chance. However, when the task difficulty was set instead at 70% correct, a new group of subjects was able to learn. Hence, learning motion discrimination was possible when MT was presumably eliminated.
Discrimination Learning↗
Effects of early postnatal gonadal steroids on the successive conditional discrimination reversal learning in the rat.
In the present study the existence of sex differences in the acquisition, retraining and reversal of a successive conditional discrimination learning (Experiment 1) and the role of the early postnatal gonadal steroids on these discrimination tasks (Experiment 2) were investigated. In Experiment 1 two groups of experimentally naive rats (males and females) were exposed to a black-white successive conditional discrimination task in a T-maze. No sex differences were found in the acquisition or retraining. However, in the reversal phase females made fewer errors and reached the discrimination criterion (90% of correct choices) sooner than males. In Experiment 2, the absence of sex differences in the acquisition or retraining phases and the existence of sexual dimorphism in the reversal period were confirmed. In addition, female androgenization and male orchidectomy, on day one after birth, reversed the direction of the sex differences found in the successive conditional discrimination reversal learning.
Androgens↗
Age-related changes in correlation between behavioral and biochemical parameters in Lewis rats.
This study evaluated aging by using a correlational analysis of behavior and biochemistry in young (4 months old) and old (24 months old) Lewis rats. The rats were subjected to different learning tasks (spatial discrimination learning in the Morris task and cone-field task, temporal discrimination learning, one-trial inhibitory avoidance task) and noncognitive tests (emotional reactivity, motor coordination, and food motivation) and the relation between the various parameters was assessed. In the learning tasks, except for the inhibitory avoidance task, the first part of the learning curve was taken as an index of learning. Blood glucose (baseline and blood glucose regulation) and hippocampal choline acetyltransferase (ChAT) activity were also measured. There was no correlation between the different parameters of learning in young and old rats. This indicates that there are individual differences in performance in different learning and memory tasks. Measures of noncognitive behavior (food motivation, emotional reactivity, and motor performance) did not predict performance in the learning tasks. Hippocampal ChAT activity did not correlate with learning performance in old rats, whereas blood glucose level was found to correlate with spatial learning in old rats. These results suggest that an impaired regulation of blood glucose may be related to cognitive performance in aging.
Age Factors↗
Discriminated escape learning and response to electric shock after 6-hydroxydopamine lesions of the nigro-neostriatal dopaminergic projection.
In an earlier report it was observed that bilateral stereotaxic injections of 6-hydroxydopamine (6-OHDA) into the zone compacta of the substantia nigra deficits in the acquisition of a conditioned avoidance response [8], The present experiments were designed to determine if either a generalized learning impairment or a decreased sensitivity to foot shock might be the basis for the avoidance deficit. It was found that rats subjected to bilateral 6-OHDA lesions of the substantia nigra learned a light discrimination shock escape habit in as few trials as unoperated controls. This observation indicates that the integrity of the dopaminergic nigro-neostriatal system is not essential for the formation of learned associations between sensory cues and motor responses. In a second experiment it was observed that neither the shock-induced flinch nor the jump threshold was elevated after nigral lesions, suggesting that these lesions do not decrease the aversive motivational properties of foot shock. In view of these findings, the nature of the avoidance deficit produced by substantia nigra lesions is discussed with reference to the possibility that they selectively block the initiation of voluntary motor responses. According to this hypothesis, the failure of these lesions to disrupt escape responding may be due to the fact that the unconditioned stimulus generates reflexive motor responses (flinch, jump, etc.) which are sufficient to begin the motor sequences that cannot be initiated voluntarily in response to the conditioned stimulus.
Animals↗
Dissociable contributions of the orbitofrontal and infralimbic cortex to pavlovian autoshaping and discrimination reversal learning: further evidence for the functional heterogeneity of the rodent frontal cortex.
To examine possible heterogeneity of function within the ventral regions of the rodent frontal cortex, the present study compared the effects of excitotoxic lesions of the orbitofrontal cortex (OFC) and the infralimbic cortex (ILC) on pavlovian autoshaping and discrimination reversal learning. During the pavlovian autoshaping task, in which rats learn to approach a stimulus predictive of reward [conditional stimulus (CS+)], only the OFC group failed to acquire discriminated approach but was unimpaired when preoperatively trained. In the visual discrimination learning and reversal task, rats were initially required to discriminate a stimulus positively associated with reward. There was no effect of either OFC or ILC lesions on discrimination learning. When the stimulus-reward contingencies were reversed, both groups of animals committed more errors, but only the OFC-lesioned animals were unable to suppress the previously rewarded stimulus-reward association, committing more "stimulus perseverative" errors. In contrast, the ILC group showed a pattern of errors that was more attributable to "learning" than perseveration. These findings suggest two types of dissociation between the effects of OFC and ILC lesions: (1) OFC lesions impaired the learning processes implicated in pavlovian autoshaping but not instrumental simultaneous discrimination learning, whereas ILC lesions were unimpaired at autoshaping and their reversal learning deficit did not reflect perseveration, and (2) OFC lesions induced perseverative responding in reversal learning but did not disinhibit responses to pavlovian CS-. In contrast, the ILC lesion had no effect on response inhibitory control in either of these settings. The findings are discussed in the context of dissociable executive functions in ventral sectors of the rat prefrontal cortex.
Animals↗
Limbic thalamic, cingulate cortical and hippocampal neuronal correlates of discriminative approach learning in rabbits.
Previous research employing lesions and recording of neuronal activity has implicated cingulothalamic and hippocampal circuitry in the mediation of discriminative instrumental avoidance learning in rabbits. This study was directed at the question of whether the cingulothalamic circuitry is specialized for avoidance learning, or whether it is also involved in appetitively motivated learning. Multi-unit neuronal recordings in the aforementioned areas were obtained as adult New-Zealand white rabbits learned to approach and orally contact a drinking spout for water reward after a tone conditional stimulus (CS+), and to ignore the spout after a different, non-predictive tone conditional stimulus (CS-). As during avoidance learning, excitatory and discriminative training-induced neuronal activity (TIA) developed during the course of approach learning. Discriminative TIA refers to development of greater neuronal firing response to the CS+ than to the CS-. Excitatory TIA refers to increased neuronal discharge magnitude during training compared to the activity elicited before training, when CS presentations were unpaired with foot-shock presentations. As during avoidance learning, TIA in anterior cingulate cortical and interconnected mediodorsal (MD) thalamic neuronal records preceded TIA in posterior cingulate cortical and interconnected anterior ventral thalamic records. Delayed changes also occurred in area CA1 of the hippocampus in parallel with changes in the posterior cingulate cortex and the anterior thalamic nuclei. In contrast to the avoidance-related activity, the changes in the thalamic areas preceded or occurred concurrently with changes in the related cingulate cortical areas. This difference is hypothesized to be due to a reduced or absent contribution of amygdaloid efferents to the approach learning-related TIA. The overall magnitude of the elicited training-induced neuronal responses was reduced, relative to the discharges during avoidance conditioning. The discharge magnitude differences suggested a greater recruitment of limbic circuit functions during avoidance learning, possibly due to the aversiveness and high arousal associated with the avoidance task. In general, the results indicate that the circuitry formed by interconnected cingulate cortical, limbic thalamic and hippocampal neurons has fundamentally similar functions in both approach and avoidance learning.
Animals↗
Preclinical effects: learned behavior.
A review of the previous Marihuana and Health Reports (1971-1975) reveals that an extensive array of experimental procedures and contexts have been used to study the effects of cannabinoids on the performance of learned behavior in animals. These preclinical behavioral experiments have provided a framework for, and guided the design of, subsequent human experimentation. Compared to previous years, only a few experiments pertaining to cannabinoids and learned behavior have appeared during the past two years. By and large these more recent experiments confirm previous findings; no particularly novel procedures have been explored nor have there been dramatically unpredictable results. In part, the decrease in activity in cannabinoid preclinical animal research on learned behavior indicates an increase in human cannabinoid-learning investigations. Several detailed taxonomies of learned behavior are possible. However, for the purposes of the present report, learned behaviors will be categorized into those involving: avoidance learning and aversive control; reinforcement schedules and maze learning; and discrimination learning.
Animals↗
DISCRIMINATED OPERANT AVOIDANCE LEARNING IN WISTAR AND G-4 RATS AS A FUNCTION OF TYPE OF WARNING STIMULUS.
Explore the source record for details and available documents.
Animals↗
FACILITATION OF DISCRIMINATED AVOIDANCE LEARNING BY DISCONTINUOUS SHOCK.
Explore the source record for details and available documents.
Avoidance Learning↗
Haptic attention and visual transfer by mentally retarded and nonretarded individuals.
Four mentally retarded and four nonretarded adolescents learned compound discriminations in the haptic (touch) modality using Ray's (1969) conflict-compound procedure. Reinforcement history was controlled so that prior reinforcement contingencies were unchanged for one element and reversed for the other element of a compound (two-element) stimulus during discrimination training. Consistent with Huguenin and Touchette's (1980) results in the visual modality, our retarded subjects evinced selective attention effects in posttraining tests conducted in the haptic modality. Results with nonretarded subjects similarly indicated that they had selectively attended to only one element of a conflict-compound stimulus during compound discrimination training. Visual transfer tests revealed that for most individuals the effects of conflict-compound discrimination training transferred from the haptic to visual sensory modalities. Results were discussed in terms of selectivity of attention to nonredundant stimulus elements as an effective strategy for discrimination learning rather than a perceptual deficit.
Adolescent↗
Developmental study of the hippocampal formation in rhesus monkeys (Macaca mulatta): II. Early ablations do not spare the capacity to retrieve conditional object-object associations.
A companion article (see record 2005-06959-001) revealed that hippocampectomy in infancy spares concurrent discrimination learning but not recognition memory. The present report describes the results obtained with a more complex task, conditional object- object association, in which rhesus monkeys (Macaca mulatta) had to first learn to discriminate between pairs of objects rather than single ones and to subsequently remember which particular object had been a member of a rewarded stimulus pair (contextual retrieval). Hippocampectomized infants obtained normal scores in learning individual pair discriminations, but they were severely impaired in contextual retrieval. The results are interpreted in terms of a dual-system theory proposed by R. Hirsh (1974). The results point out not only the importance of age at testing but also the nature of the task. The authors were also able to glimpse possible instances of cooperation or competition between the 2 systems.
Age Factors↗