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 1,693 records · Page 94Linked to original sources
PubMed1987

Effect of teratogenic exposure on the developing brain: research strategies and possible mechanisms.

Some of the problems associated with human behavioral teratology are reviewed and research strategies necessary for the elucidation of the possible prenatal bases for the later occurrence of Learning Disabilities (LD) are suggested. An animal model for LD was created by exposure of female rats during pregnancy or during lactation to diazepam, monosodium glutamate, caffeine, or maternal stress. The gestation period most sensitive to these prenatal insults was established, and some of the neurochemical and histological correlates of the resulting discrimination learning deficits were investigated.

Animals↗
PubMed1987

Delayed temporal discrimination in pigeons: A comparison of two procedures.

A within-subjects comparison was made of pigeons' performance on two temporal discrimination procedures that were signaled by differently colored keylight samples. During stimulus trials, a peck on the key displaying a slanted line was reinforced following short keylight samples, and a peck on the key displaying a horizontal line was reinforced following long keylight samples, regardless of the location of the stimuli on those two choice keys. During position trials, a peck on the left key was reinforced following short keylight samples and a peck on the right key was reinforced following long keylight samples, regardless of which line stimulus appeared on the correct key. Thus, on stimulus trials, the correct choice key could not be discriminated prior to the presentation of the test stimuli, whereas on position trials, the correct choice key could be discriminated during the presentation of the sample stimulus. During Phase 1, with a 0-s delay between sample and choice stimuli, discrimination learning was faster on position trials than on stimulus trials for all 4 birds. During Phase 2, 0-, 0.5-, and 1.0-s delays produced differential loss of stimulus control under the two tasks for 2 birds. Response patterns during the delay intervals provided some evidence for differential mediation of the two delayed discriminations. These between-task differences suggest that the same processes may not mediate performance in each.

Journal Article↗
PubMed1993

Behavioral effects of non-NMDA glutamate receptor antagonists.

Non-NMDA receptor antagonists decrease motor activity in some situations, alter the sleep-wake cycle, possess anticonvulsant and neuroprotectant actions, and appear to impair some learning tasks but not others. NMDA receptor antagonists affect these same functions but often in different and even opposite ways. NMDA receptor antagonists impair many different spatial learning tasks, including the Morris water maze, the Olton radial maze, and the hole-board task. Non-NMDA receptor antagonists are either ineffective in these spatial tasks or have not yet been evaluated. However, non-NMDA receptor antagonists may impair associative processes required in a bar-press response and in discrimination learning. Further research is needed in the context of comparing NMDA as opposed to non-NMDA receptor antagonists within the same paradigm.

Animals↗
PubMed2003

Learning to predict protein-protein interactions from protein sequences.

In order to understand the molecular machinery of the cell, we need to know about the multitude of protein-protein interactions that allow the cell to function. High-throughput technologies provide some data about these interactions, but so far that data is fairly noisy. Therefore, computational techniques for predicting protein-protein interactions could be of significant value. One approach to predicting interactions in silico is to produce from first principles a detailed model of a candidate interaction. We take an alternative approach, employing a relatively simple model that learns dynamically from a large collection of data. In this work, we describe an attraction-repulsion model, in which the interaction between a pair of proteins is represented as the sum of attractive and repulsive forces associated with small, domain- or motif-sized features along the length of each protein. The model is discriminative, learning simultaneously from known interactions and from pairs of proteins that are known (or suspected) not to interact. The model is efficient to compute and scales well to very large collections of data. In a cross-validated comparison using known yeast interactions, the attraction-repulsion method performs better than several competing techniques.

Algorithms↗
PubMed2006

A fast learning algorithm for deep belief nets.

We show how to use "complementary priors" to eliminate the explaining-away effects that make inference difficult in densely connected belief nets that have many hidden layers. Using complementary priors, we derive a fast, greedy algorithm that can learn deep, directed belief networks one layer at a time, provided the top two layers form an undirected associative memory. The fast, greedy algorithm is used to initialize a slower learning procedure that fine-tunes the weights using a contrastive version of the wake-sleep algorithm. After fine-tuning, a network with three hidden layers forms a very good generative model of the joint distribution of handwritten digit images and their labels. This generative model gives better digit classification than the best discriminative learning algorithms. The low-dimensional manifolds on which the digits lie are modeled by long ravines in the free-energy landscape of the top-level associative memory, and it is easy to explore these ravines by using the directed connections to display what the associative memory has in mind.

Algorithms↗
PubMedDate not supplied

Developmental chlorpyrifos effects on hatchling zebrafish swimming behavior.

Chlorpyrifos (CPF), a widely used organophosphate insecticide and potent acetylcholinesterase inhibitor, interferes with neurobehavioral development. Rat models have been key in demonstrating that developmental CPF exposure causes learning deficits and locomotor activity alterations, which persist into adulthood. Complementary nonmammalian models can be useful in determining the neurodevelopmental mechanisms underlying these persisting behavioral effects. Zebrafish (Danio rerio) with their clear chorion and extensive developmental information base provide an excellent model for assessment of molecular processes of toxicant-impacted neurodevelopment. We have developed methods for assessing spatial discrimination learning in adult zebrafish and have documented persisting effects of developmental CPF exposure on swimming activity and learning after low and high doses of CPF (10 and 100 ng/ml) administered to zebrafish embryos on Days 1-5 postfertilization (pf). In the current study, we developed methods for behavioral assessment of CPF exposure on swimming activity in newly hatched zebrafish. An equal area segmented annular grid (concentric circles divided into quadrants through the diameter) was made in a 16-mm diameter cylinder. The test area was placed on a heating device secured to an Olympus SZH10 dissecting scope stage. Zebrafish embryos were exposed to 10 ng/ml CPF, 100 ng/ml CPF, or vehicle control (25 microl/ml DMSO) (n=8-10/treatment group). Each treatment group was kept in a total volume of 25 ml of egg water (60 mg/ml Instant Ocean) including DMSO with or without CPF mixed to above dilutions in an incubator set at 28.5 degrees C. CPF dilutions or vehicle were changed daily with exposure ending on Day 5 pf. Testing of larval zebrafish was performed on Days 6 and 9 pf. The fish were placed in the test cylinder with 1.5 ml of egg H(2)O (28.5 degrees C). After a 2-min acclimation period, the swimming activity of the fish was measured for a 3-min testing session. The 100 ng/ml CPF dose caused significant slowing of swimming activity on Days 6 and 9 pf and had persisting effects of impairing spatial discrimination and decreasing response latency in adulthood. Developmental exposure to 10 ng/ml of CPF did not cause a significant change in locomotor activity during the period soon after hatching. CPF exposure during early development caused clear behavioral impairments detectable during the posthatching period. In a previous study, we found that early developmental CPF exposure caused behavioral alterations in zebrafish, which lasted throughout adulthood. The molecular mechanisms by which early developmental CPF exposure produces these behavioral impairments expressed in adulthood can now be studied in the zebrafish model.

Animals↗
PubMed1999

Discriminative effects of compound drug stimuli: a focus on attention.

Discrimination research has increasingly used compound stimuli emerging from drugs acting through multiple neurotransmitter systems or from injections of drug mixtures that approximate "street-wise" drug-taking behaviors. Accompanying this trend has been an interest in the role of cognitive factors in drug discrimination learning. Accounts of multidimensional drug stimuli have focused mainly on specific neuronal mechanisms, and have largely ignored the contribution of stimulus information to the perception of internal events or to the selection processes, heretofore called attention mechanisms, which may underlie the observer's idiosyncratic response to drug administration. It is argued here that research in drug discrimination may benefit from a more detailed consideration of the processes by which an observer interacts with the emergent stimulus properties of drug administration. Therapeutic intervention initiatives may critically depend on knowing the interactions between the specific attributes of the drug experience that capture the attention of the individual and that may later acquire stimulus control over complex drug-taking behaviors.

Animals↗
PubMed1987

Central sites involved in lateral hypothalamus conditioned neural responses to acoustic cues in the rat.

1. Unit activity in the lateral hypothalamus (LHA) of the rat was recorded during discrimination learning of cue-tone stimuli (CTS) predicting glucose (CTS1+) or intracranial self-stimulation (ICSS) (CTS2+) as positive reinforcement or electric shock (CTS1-) or tail pinch (CTS2-) as negative reinforcement. The same action, licking, was used as the behavioral response to all stimuli. Procaine hydrochloride, a local anesthetic, was microinjected into the ventral tegmental area (VTA) and the amygdala (AM). LHA neuron responses and licking were analyzed to investigate the afferent input pathway(s) responsible for LHA neural responses to conditioning CTSs in positive reinforcement and to identify the central site involved in CTS learning. Although the animals were restrained, there was no respiratory, cardiac rate, or blood pressure evidence of stress. The headholder was specially designed in our laboratory to avoid pain or discomfort to the animal. The subjects would often, after the first few sessions, voluntarily enter into position in the apparatus, presumably to obtain the reward available during the experiments. 2. In positive reinforcement, a rat was rewarded by 5 microliters of glucose or ICSS when it licked a spout. The rat licked for glucose after CTS1+ or for ICSS after CTS2+. In negative reinforcement, an aversive stimulus, either electric shock or tail pinch, was applied if the rat did not lick the spout. The electric shock and tail pinch were maintained weak enough to produce an avoidance ratio less than 20-30%, averaged in all trials. The rat licked to avoid electric shock after CTS1- or tail pinch after CTS2-. 3. Of 271 LHA neurons analyzed, 202 (74.5%) responded to either or both rewarding and aversive stimuli. The number of neurons that responded to only rewarding stimuli was relatively large (105/271), and the number that responded similarly to both rewarding and aversive stimuli was small (29/271). The effects of both glucose and ICSS, and the effects of both electric shock and tail pinch, were usually similar in neurons analyzed for both rewarding and aversive stimulation. Of 271 neurons, 173 responded differentially to rewarding and aversive stimuli. 4. Neural and behavioral responses were recorded before, during, and after local anesthesia of the VTA in 15 rats and of the AM in 14 rats. Injections of 0.3-0.8 microliters of 5% procaine hydrochloride or 0.9% saline were made at a rate of 0.3 microliters/min through guide cannulae chronically implanted in the VTA and AM, ipsilateral to the recording and ICSS sites in 29 rats that self-stimulated.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗
PubMed2004

Spatial learning in rats is impaired by microinfusions of protein kinase C-gamma antisense oligodeoxynucleotide within the nucleus accumbens.

The nucleus accumbens (NAcc) has been shown to play a role in motor and spatial learning. Protein kinase C (PKC) has been implicated in the mechanisms of initiation and maintenance of long-term potentiation that is thought to be involved in the storage of long-term memory. In the present study, the importance of de novo synthesis of PKC-gamma within the NAcc in the acquisition and retention of spatial discrimination learning was assessed using an antisense knockdown approach. Separate groups of Long-Evans rats were exposed to acute microinfusions (6microg/microl) of PKC-gamma antisense oligodeoxynucleotide (AS-ODN), control oligodeoxynucleotide (C-ODN) or vehicle into the NAcc at 24 and 3h before each training session. Behavioral findings showed that the blockade of NAcc-PKC-gamma translation caused impairments in the early phase of learning and retention of spatial information. Biochemical experiments showed that PKC-gamma expression was reduced and Ca(2+)/phospholipid-dependent protein kinase C (PKC) activity was blocked significantly in the AS-ODN-treated rats in comparison with control rats. The present findings suggest that NAcc-PKC-gamma plays a role during the early acquisition of spatial learning. Also, retention test results suggest that NAcc-PKC-gamma may be working as an intermediate factor involved in the onset of molecular mechanisms necessary for spatial memory consolidation within the NAcc.

Animals↗
PubMedDate not supplied

Learning behavior, escape behavior, and depression in an ulcer susceptible rat strain.

The aim of the present study was to explore the relationship between depression (helpless withdrawal behavior) and susceptibility to stress ulcer in rats. The WKY genetic strain of rats has been described as highly susceptible to stomach ulcer development during water restraint, i.e., when placed in a jar of water and forced to swim to keep their head above water, a setting in which Richter identified "giving up" behavior akin to hopelessness (Richter, 1957). Since WKY rats tended to float in the water instead of swimming in an attempt to escape, and were also found to be relatively inactive in open field tests, a series of experiments were performed to ascertain whether their diminished activity and their failure to swim reflected slowness, cognitive impairment, or something actually akin to depression. The latter interpretation was supported by evidence from tests of shock avoidance behavior, of capacity to learn discrimination in an operant setting, and by the capacity of an antidepressive drug to lessen floating time in the forced swim test and also to reduce the incidence of stomach ulcers.

Animals↗
PubMedDate not supplied

Acute ethanol exposure during pregnancy in rats: effects upon a multiple learning task.

Pregnant rats received 4.8 g/kg of 20% (v/v) ethanol IP or identical volume of saline during gestational Day 8. No signs of gross physical teratogenesis were evident in the offspring as expressed by litter size, weight and external malformations at birth. However, when offspring were subjected to a multiple fixed ratio-4/differential reinforcement of low rate of responding 10-sec ( FR 4/DRL 10 sec) schedule of reinforcement at 60 days of age, significant differences were observed in the performance of DRL 10-sec schedule that required visual discrimination and response inhibition, but not in the FR 4 schedule that required a relatively simple nondiscrimination task of active-response. Bar press rates were unaffected by prenatal treatment since no differences between groups were found in the number of total responses performed on either component of the multiple schedule. Present results are discussed in terms of either response perseveration or a lower aptitude to deal with low rates of responding-discrimination learning tasks on the animals prenatally exposed to alcohol.

Analysis of Variance↗
PubMed1999

Discriminative stimulus effects of nalbuphine in nontreated and morphine-treated pigeons.

In the present study, the stimulus effects of the low efficacy agonist nalbuphine were examined under two conditions: nontreated and morphine treated. In the first experiment, five pigeons were trained to discriminate among 3.2 mg/kg morphine, 5.6 mg/kg nalbuphine, and saline. Nalbuphine produced nalbuphine-like responding. Low doses of morphine produced nalbuphine-like responding, whereas high doses produced morphine-like responding. Naltrexone produced saline-like responding and reversed the stimulus effects produced by the training doses of morphine and nalbuphine. Five different pigeons were treated daily with 10 mg/kg morphine (i.m.) and trained 6 h later to discriminate among 10 mg/kg morphine, 1.0 mg/kg nalbuphine and saline. In these pigeons, morphine produced morphine-like responding and nalbuphine produced nalbuphine-like responding. Morphine abstinence produced nalbuphine-like responding that was reversed by morphine. Additionally, naltrexone produced nalbuphine-like responding. These data suggest that the discrimination between morphine and nalbuphine in the nontreated and morphine-treated pigeons may be based on the relative efficacy differences between morphine, a higher efficacy mu-agonist, and nalbuphine a lower efficacy mu-agonist.

Analgesics, Opioid↗
PubMedDate not supplied

Operant behavior as a technique for toxicity testing.

Behavioral toxicology is a discipline which has evolved out of the need for data on the effects of toxic agents on the function of the central nervous system. To date the field is divided over the question of which behavioral models to use to detect behavioral toxicities. Operant conditioning and schedule-controlled responding have been used as baselines for testing pharmacological agents for nearly 40 years, and there is no reason that the developing field of behavioral toxicology cannot take advantage of the lessons learned during this 40-year period. Behaviors maintained by operant conditioning procedures have proven to be sensitive to a wide range of chemicals. Using these procedures, behavior has been shown to; be sensitive to toxic agents, provide data relevant to the question of behavioral specificity, provide a stable baseline for extended periods of time, and allow for the assessment of specific functions such as temporal discrimination, learning and memory, and sensory system function.

Animals↗
PubMed1986

Hypothalamic neuron involvement in integration of reward, aversion, and cue signals.

The lateral hypothalamus (LHA) is involved in integrative functions related to emotion, reward, aversion, and learning. It is, however, unclear whether the medial forebrain bundle (MFB) forms a substrate common to the anterior and posterior hypothalamic areas or whether information regarding rewarding and aversive stimuli converges on and is integrated by the same hypothalamic neuron. In the present study, unit activity in the LHA and lateral preoptic-anterior hypothalamic area (lPOA-AHA) of the rat was recorded during discrimination learning of cue tone stimuli (CTS) that predicted glucose or intracranial self-stimulation (ICSS) as rewarding stimuli, or electric shock or tail pinch as aversive stimuli, using identical behavior, licking. We examined functional differences between the LHA and lPOA-AHA. In positive reinforcement experiments a rat was rewarded by glucose or ICSS only when it licked a spout presented in front of its mouth. The threshold current for ICSS was used. In negative reinforcement experiments an aversive stimulus, either electric shock or tail pinch was applied if the rat did not lick the spout. The strengths of electric shock and tail pinch were selected to produce an avoidance ratio less than 20-30%, averaged in all trials. The activity of 507 LHA and 249 lPOA-AHA neurons was analyzed during both glucose and ICSS trials. The effects of both glucose and ICSS on the same LHA or lPOA-AHA neuron were usually in the same direction, i.e., either both excitatory or both inhibitory. Of 143 LHA and 44 lPOA-AHA neurons that responded to both rewards, the responses of 117 (81.8%) LHA and 35 (79.5%) lPOA-AHA neurons to both stimuli were similar. The activity of 131 LHA and 153 lPOA-AHA neurons was analyzed in both electric shock and tail pinch trials. The effects of both electric shock and tail pinch on the same LHA or lPOA-AHA neuron were usually in the same direction. Of 29 LHA and 27 lPOA-AHA neurons that responded to both aversive stimuli, the responses of 28 (96.6%) LHA and 25 (92.6%) lPOA-AHA neurons to both were similar. The activity of 170 LHA and 195 lPOA-AHA neurons in response to both rewarding glucose and/or ICSS stimulation and aversive electric shock and/or tail pinch was analyzed. About one-third of the neurons in each area were reward specific (57/170 in LHA; 63/195 in lPOA-AHA), whereas relatively few were aversion specific in each area (21/170 in LHA; 15/195 in lPOA-AHA).(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗
PubMed2006

Neonatal lesions of the ventral hippocampus in rats lead to prefrontal cognitive deficits at two maturational stages.

This experiment assessed the effect of neonatal ventral hippocampus lesions in rats, a heuristic approach to model schizophrenia, on continuous delayed alternation and conditional discrimination learning performance before and after complete cerebral maturation. Delays (0, 5, 15, and 30 s) were introduced in the tasks to help dissociate between a hippocampal and a prefrontal cortex dysfunction. At postnatal day (PND) 6 or 7, rats received bilateral microinjections of ibotenic acid or phosphate-buffered saline in the ventral hippocampus. From PND 26 to PND 35, rats were tested on the alternation task in a T-maze; from PND 47 to PND 85, the same rats were tested in the discrimination task where a stimulus and a response location had to be paired. Deficits in ventral hippocampus-lesioned rats were observed in both tasks whether a delay was introduced before a response or not. Impaired performance regardless of delay length, combined with high rates of perseverative errors, suggested a post-lesional prefrontal cortex dysfunction which persisted from the juvenile stage into adulthood. Premature cognitive impairments could not be predicted on the basis of the neurodevelopmental animal model of schizophrenia. Nevertheless, they appear consistent with accounts of premorbidly compromised memory, both immediate and delayed, in subgroups of schizophrenia patients.

Aging↗