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 1,729 records · Page 96Linked to original sources
PubMed1996

Metabotropic glutamate receptors in hippocampal long-term potentiation and learning and memory.

Glutamate receptors have been identified as important interfaces in learning and memory paradigms as well as in mechanisms of synaptic plasticity, such as long-term potentiation (LTP) and long-term depression (LTD), which are believed to be the underlying cellular basis of at least some forms of learning. Although investigations of G-protein-coupled receptors have a long history, those depending on ligand-binding of glutamate have only been discovered recently, and this is the reason why our knowledge about metabotropic glutamate receptors (mGluRs) is at present very limited. However, the development of relatively specific antagonists and agonists has enabled the analysis of the role of mGluRs in synaptic plasticity, mostly studied on the models of LTP and LTD. Among others, we have been able to demonstrate that activation of mGluRs is essential for induction and maintenance of long-lasting hippocampal LTP in vitro and in vivo. The work conducted by several groups, including ours, has now provided compelling evidence that mGluR activation is an important step in the cellular cascades leading to memory formation in vertebrates. This led us to assume, given that the hippocampus plays a prominent role in spatial rather than discrimination learning, that mGluRs may participate in the processing of spatial information via hippocampal mechanisms, and may thus be similarly important as N-methyl-D-aspartate receptors. This article surveys the literature dealing with mGluRs in hippocampal LTP and learning and memory. We will demonstrate that, although the understanding of cellular mechanisms of neuronal plasticity and of the pharmacology of learning and memory has advanced, the missing link to prove that LTP is a substrate for some form forms of learning still remains unsolved. Nevertheless, it appears reasonable to argue that mGluRs in LTP and learning may share some, but not all features, and it will be an interesting approach for further analysis to address the unresolved issues.

Animals↗
PubMed2005

A preclinical comparison between different opioids: antinociceptive versus adverse effects.

Reduced side-effect liability of opioids may enhance the patient's quality of life and decrease the incidence of opioid-insensitive pain. Literature offers few comparative data between different opioids at equianalgesic doses. Therefore morphine, fentanyl, buprenorphine, codeine, hydrocodone and oxycodone were compared for analgesic properties and side-effect profiles in rats. Analgesic efficacy was analysed using a tail withdrawal test for acute thermal nociception, a formalin test for chemically induced inflammatory pain and a von Frey test for mechanical hypersensitivity. For side-effect profiling inhibition of gastrointestinal activity was evaluated in a charcoal and ricinus oil test, arterial PCO(2) was determined for measuring respiratory depression, the discriminative stimulus properties linked to the narcotic cue were assessed using a drug discrimination learning test, and motor coordination was tested through rotarod performance. ED(50)'s for the occurrence of side-effects were compared to ED(50)'s in behavioural pain tests. Fentanyl had a strong analgesic potency and, compared to other opioids, an acceptable side-effect profiling at analgesic ED(50)'s. Also consistent was the ceiling effect of buprenorphine implying an increased safety margin for side-effects, but a decreased analgesic efficacy. Differences between opioids as observed in this study can have important indications for their use in acute as well as in the onset of chronic treatments.

Analgesics↗
PubMed2005

Context-dependency of cue-elicited urge to smoke.

AIMS: Earlier studies have suggested that the cue-induced urge to smoke depends on the expectation of the availability of smoking. The present study investigated whether a 'room context' change could undo the learned discrimination between two stimuli, respectively, predicting smoking availability or smoking unavailability. DESIGN: A 2 (smoking cue) x 2 (availability context cue) x 6 (trial) x 2 (room context change) within-subjects design was used. Participants were repeatedly presented with a context cue predicting smoking availability (blue serving tray) and a context cue predicting unavailability (yellow serving tray) in one room and tested for an effect of context change in a different room. SETTING: Two distinct rooms located in different department buildings of Maastricht University. PARTICIPANTS: Seventeen daily smokers who had smoked at least five cigarettes a day for at least 2 years. MEASUREMENTS: Self-reported urge to smoke using a visual analogue scale (VAS). FINDINGS AND CONCLUSIONS: Results replicated the finding that a context cue that predicted smoking elicited greater urges to smoke than a context cue that predicted no smoking, irrespective of the presence of smoking cues. In addition, this study showed that this differential effect on the urge to smoke was generalized to a context other than the context in which learning took place. These findings are discussed in relation to the significance of a context change regarding the predictive value of smoking availability.

Adult↗
PubMed1993

Damage to the perirhinal cortex exacerbates memory impairment following lesions to the hippocampal formation.

Recent work has been directed at identifying the critical components of the medial temporal lobe that, when damaged, produce severe memory impairment. The H+A+ lesion includes the hippocampal formation, the amygdala, and the adjacent entorhinal, parahippocampal, and perirhinal cortices. A more restricted medial temporal lobe lesion that includes the hippocampal formation and parahippocampal cortex (the H+ lesion) produces less severe memory impairment. Previous work demonstrated that extending the H+ lesion forward to include the amygdala did not exacerbate the impairment. Here, we tested the hypothesis that extending the H+ lesion forward to include the perirhinal cortex (the H++ lesion), but sparing the amygdala, should produce a more severe memory impairment and one that would approximate the level of memory impairment associated with the H+A+ lesion. Monkeys with the H++ lesion were severely impaired on two of three amnesia-sensitive tasks (delayed nonmatching to sample and delayed retention of object discrimination). On the third amnesia-sensitive task (concurrent discrimination learning), two of the monkeys in the H++ group obtained poorer scores than all seven normal monkeys, although the overall group comparison was not significant. The memory impairment following H++ damage was more severe overall than the impairment associated with the H+ lesion and approached the level of impairment associated with the H+A+ lesions. Quantitative measurement of damage in each anatomical component of the lesion indicated that the perirhinal cortex was the only brain region that was more extensively damaged in the H++ group than in the H+ group. These findings emphasize the importance of the perirhinal cortex in the anatomy of the medial temporal lobe memory system.

Animals↗
PubMed1991

Extra-dimensional versus intra-dimensional set shifting performance following frontal lobe excisions, temporal lobe excisions or amygdalo-hippocampectomy in man.

Attentional "set" shifting was assessed in a group of 20 neurosurgical patients with localized excisions of the frontal lobes, a group of 20 patients with unilateral temporal lobe lesions and a group of 11 patients who had undergone amygdalo-hippocampus removal. These three patient groups were compared with groups of both young (age-matched) and elderly normal control volunteers on a computerized test of visual discrimination learning involving both an intra- and an extra-dimensional shift. The frontal lobe group were selectively impaired in their ability to shift response set to a previously irrelevant dimension but not to shift attention to new exemplars of a previously relevant dimension. A similar pattern was observed in the elderly group of normal control volunteers. By comparison, both the temporal lobe patients and the amygdalo-hippocampectomy patients were unimpaired in their ability to perform either shift, although both groups had significantly prolonged selection latencies at the extra-dimensional shift stage of the task. These data are compared to previous findings from patients with idiopathic Parkinson's disease and are discussed in terms of a specific attentional set shifting deficit following frontal lobe damage.

Adult↗
PubMed1997

Perceptual learning of orientation discrimination by more than one attribute.

Using a perceptual learning paradigm, we evaluated whether information from the attributes: color, luminance and motion is combined to provide orientation coding. Four observers were trained to discriminate the orientation between color-defined bars, four between luminance-defined bars, and four between motion-defined bars. Before and after training, they were tested with each of the three attributes separately and all superimposed, at the same and at a different location as the one seen during training. A similar improvement was found whether the bars seen after training were defined by the same, or by a different attribute as the one seen during training, or by the three attributes superimposed. This improvement was significantly more substantial at the location where the bars were presented during training. Moreover, orientation discrimination was always better when the bars were defined by three attributes than by any one alone. Because the improvement was retinotopic and not restricted to the attribute seen during training, we suggest that training changed the sensitivity of orientation-selective cells responsive to color, luminance and motion. Moreover, the overall better performance with additional attributes supported an integration of information from color, luminance, and motion at a common site for orientation coding.

Analysis of Variance↗
PubMed1985

Neurochemical studies on imprinting behavior in chick and duckling.

The effect of lesions in the parts of medial hyperstriatum ventrale (MHV) or lateral neostriatum (LN) on imprinting behavior was examined. Bilateral lesions in MHV severely impaired imprinting behavior in ducklings, but lesions in LN did not impair such behavior. On the other hand, the birds lesioned in MHV still had brightness discriminative learning ability with perfect performance of visuomotor coordination. The neurotransmitter candidates controlling imprinting behavior in MHV were investigated using blockers of neurotransmission. 6-Hydroxydopamine (6-OHDA) and haloperidole injected into MHV did not have specific effect on imprinting behavior although catecholamine contents in MHV was clearly decreased and locomotor activity was strongly suppressed. Atropine injection into MHV caused significant impairment of following behaviour, but locomotor activity was not affected. The injection of atropine into other region did not have any effect. alpha-Bungarotoxin showed no effect on either imprinting or locomotor activity. Kainic acid injection into MHV caused the decrease of glutamate content in the MHV region and it reached maximum at 24 hours after injection. However, imprinting behavior was already impaired at 3 hours after injection, but at 24 hours it had been recovered. A same effect was observed by glutamate injection. The effect of protein synthesis inhibitor on the acquisition process of imprinting was investigated. The acquisition of imprinting was significantly impaired by cycloheximide (CHX) injection into MHV within 2 hours after the first exposure to the imprinting stimulus. When CHX was given 24 hours after, imprinting behavior was not affected.

Animals↗
PubMed2000

Mismatch negativity (MMN) as a tool for investigating auditory discrimination and sensory memory in infants and children.

For decades behavioral methods, such as the head-turning or sucking paradigms, have been the primary methods to investigate auditory discrimination, learning and the function of sensory memory in infancy and early childhood. During recent years, however, a new method for investigating these issues in children has emerged. This method makes use of the mismatch negativity (MMN), the brain's automatic change-detection response, which has been used intensively in both basic and clinical studies in adults for twenty years. This review demonstrates that, unlike many other components of event-related potentials, the MMN is developmentally quite stable and can be obtained even from pre-term infants. Further, MMN amplitude is only slightly smaller in infants than is usually reported in school-age children and it does not seem to differ much from that obtained in adults. MMN latency has been reported to be slightly longer in infants than in adults but reaches adult values by the early school-age years. Child MMN does not seem to be analogous to adult MMN, however. For example, contrary to the results of adult studies, a prominent MMN can be obtained from in all waking- and sleep states in infants. Moreover, MMN scalp distribution seems to be broader and more central in children than in adults.

Adult↗
PubMed1975

Light-dark discrimination and reversal learning in early postnatal kittens.

During the early postnatal period kittens were trained in a visual discrimination task involving light-dark stimuli in order to determine the age of onset of visual control of learned behavior. A Y water maze was used with escape from water as the reinforcer. The results indicate that kittens are able to master the discrimination within the 5th week of life. The relevance of this result to electrophysiological measures of maturation is discussed.

Age Factors↗
PubMed1996

Young infants' long-term auditory memory: evidence for changes in preference as a function of delay.

Infants' preferences for a novel or familiar nursery rhyme were examined as an index of long-term memory. One-to 2-month-old infants' preference were tested, using a nonnutritive sucking, discrimination-learning procedure, at 1, 2, or 3 days after the last of multiple familiarization sessions. A consistent novelty preference was observed at the 1-day retention interval, no consistent preference occurred at the 2-day interval, and familiarity preference was found following the 3-day interval. This pattern of results is consistent with attentional preference models which interpret novelty and familiarity preferences as reflecting the discrepancy between an external stimulus and the infants' representation of the stimulus. The findings also reveal that infants as young as 1 month of age encoded and subsequently recognized a repeatedly experienced nursery rhyme after a 3-day retention interval.

Female↗
PubMed1980

Gender and early environmental influences on activity, overresponsiveness, and exploration.

One hundred eighty-five rats reared in either an enriched or restricted environment were tested during adulthood to determine the influence of gender and rearing environment on 3 related response characteristics, activity, overresponsiveness, and exploratory behavior. Eight experiments were performed. It was found that although females are more active than males, rearing environment does not influence behavior in the running wheel or open field. When tested in a complex compartmentalized open field, females in general and restricted rats are significantly more active than enriched males. In addition, over subsequent testing, restricted animals are increasingly responsive and fail to habituate to the testing stimuli. When tested and retested for maze learning ability, males excel over females; enriched rats maintain their ability to outperform restricted rats, although both groups had previously learned the problem. Moreover, enriched rats demonstrate a greater tendency to explore and make irrelevant section entries on a maze that is problem free. Restricted rats, specifically, and females generally, have difficulty suppressing a learned repetitious pattern of rewarded responding when it is subsequently punished; restricted rats were deficient in the ability to passively avoid or escape noxious stimuli. These experiments, as well as supporting evidence in the literature, indicate that rats reared in a restricted environment develop a limited behavioral repertoire which is characterized by a generalized tendency to overrespond, a propensity towards perseverating in repetitious patterns of limited and circumscribed responding, and a failure to habituate to repeated contact with novel stimuli.

Aging↗
PubMed1984

Role of the caudate nucleus in recovery from neonatal mediofrontal cortex lesions in the rat.

Ablation of medial prefrontal cortex impairs spatial discrimination learning in adult but not in neonatally lesioned rats. Orbital prefrontal cortex and adjacent convexity neocortex need not be left intact to observe this sparing of function. This study examined the possibility that the caudate nucleus, remaining intact after early medial prefrontal cortex lesions, might be involved in the observed behavioral sparing. Neonatal rats given combined lesions of the medial prefrontal cortex and head of the caudate nucleus were compared to age/litter-matched sham-operated controls on spatial alternation and place response acquisition and "reversal" tests. The results show that the performance of these neonatally lesioned subjects was deficient on both tests. The discussion centers on possible recovery mechanisms in rats given prefrontothalamic system damage early in life.

Animals↗
PubMed2006

Inhibition of glycogenolysis in astrocytes interrupts memory consolidation in young chickens.

Glycolysis and glycogenolysis are involved in memory processing in day-old chickens and, aside from the provision of energy for neuronal and astrocytic energy metabolism these pathways enable astrocytes to supply neurones with precursor for transmitter glutamate by glucose-based de novo synthesis. We have previously shown that memory processing for bead discrimination learning is dependent on glycolysis; however, the metabolic inhibitor used, iodoacetate, inhibits pyruvate formation from both glucose and glycogen. At specific time points after training transient reductions in brain glycogen content occur, mirrored by increases in glutamate/glutamine content. In the present study, we used intracerebral injection of a glycogen phosphorylase inhibitor, 1,4-dideoxy-1,4-imino-D-arabinitol (DAB), which does not affect glucose breakdown, to evaluate the role of glycogen metabolism in memory consolidation. Dose-dependent inhibition of learning occurred when DAB was administered at specific time periods in relation to training: (i) 5 min before training, (ii) around 30 min posttraining, and (iii) 55 min posttraining. After injection at either of the two earlier periods, memory disappeared after consolidation 30 min postlearning, and after injection 55 min after learning memory was absent at 70 min. The memory loss caused by early administration could be prevented after training by central injection of the glutamate precursor glutamine or the astrocyte-specific substrate acetate together with aspartate, substituting for pyruvate carboxylation. Thus, glycogenolysis is essential for learning in this paradigm and, aside from energy supply considerations, we suggest that an important role for glycogenolysis is to provide neurones with glutamine as the precursor for neuronal glutamate and GABA.

Animals↗
PubMed2003

Dissociation of human and computer voices in the brain: evidence for a preattentive gestalt-like perception.

We investigated the early ("preattentive") cortical processing of voice information, using the so-called "mismatch response". This brain potential allows inferences to be made about the sensory short-term store. Most importantly, the mismatch potential also provides information about the organization of long-term memory traces in the auditory system. Such traces have reliably been reported for phonemes. However, it is unclear whether they also exist for human voice information. To explore this issue, 10 healthy subjects were presented with a single word stimulus uttered by voices of different prototypicality (natural, manipulated, synthetic) in a mismatch experiment (stimulus duration 380 msec, onset-to-onset interval 900 msec). The event-related magnetic fields were recorded by a 148-channel whole-head magnetometer and a source current density modeling of the magnetic field data was performed using a minimum-norm estimate. Each deviating voice signal in a series of standard-voice stimuli evoked a mismatch response that was localized in temporal brain regions bilaterally. Increased mismatch related magnetic flux was observed in response to decreased prototypicality of a presented voice signal, but did not correspond to the acoustic similarity of standard voice and deviant voices. We, therefore, conclude that the mismatch activation predominantly reflects the ecological validity of the voice signals. We further demonstrate that the findings cannot be explained by mere acoustic feature processing, but rather point towards a holistic mapping of the incoming voice signal onto long-term representations in the auditory memory.

Acoustic Stimulation↗
PubMed1998

Clinical assessment of olfactory dysfunction in Parkinson's disease.

We used two simple tasks to test the capacities of patients with Parkinson's disease to discriminate and identify olfactory stimuli. The patients presented defective odor identification abilities whereas their capacity to discriminate between odors was apparently unaffected. This raises a question about the nature of olfactory dysfunction in Parkinson's disease. Further clinical data is required for analysis of this dysfunction. We therefore propose simple and rapid tests appropriate for clinical use with Parkinson's disease patients.

Adult↗
PubMed1989

Evaluation of the bioeffects of prenatal ultrasound exposure in the cynomolgus macaque (Macaca fascicularis): II. Growth and behavior during the first year.

The extensive use of ultrasonography for the prenatal assessment of growth and development continues to present questions regarding biological effects. We are currently evaluating a nonhuman primate model (Macaca fascicularis) exposed to ultrasound from gestational day (GD) 21 to 152 +/- 2. Exposures were performed with a commercial real-time sector scanner (ATL, MK 600); animals were scanned five times weekly on GD 21-35 +/- 2, three times weekly on GD 36-60 +/- 2, and once weekly on GD 61-150 +/- 2. The length of exposure was approximately the same as human exposure (GD 21-60 +/- 2 = 10 min/exam and GD 61-150 +/- 2 = 20 min/exam) although the frequency of the examinations was considerably greater. Initial reports indicated differences between control and treated animals including lower birth weight, higher simian Apgar scores, and changes in select hematologic parameters. Follow-up evaluations of growth during the first year included measurements of body weight, hand and foot lengths, humerus and femur lengths, biparietal and occipitofrontal diameters, head circumference, arm circumference, chest circumference, skinfold thickness, and crown-rump length. Results indicated a significant reduction in body weight in treated animals during the first three months, with nonsignificant differences during the following nine months. Hematologic analysis including complete blood counts (CBC) and clinical biochemistry at 6, 9, and 12 months of age were not significantly different. A series of behavioral evaluations including a neurobehavioral test battery (NBT) and tests assessing motor and cognitive skills were included. The NBT revealed increased muscle tone in treated animals at one, two, and four days. In an observation cage (week 1-14) more quiet activities were displayed by treated animals. Group differences in performance of motor and cognitive tasks were observed and may be attributable to agitation and difficulties in adjusting to test environments. There were no group differences observed in discrimination learning. When considering the possible implications to the human population, it is important to consider the amount of exposure these animals received, and the fact that most of the effects observed appeared to be transitory. Although human epidemiological studies have not revealed any significant bioeffects, the "prudent use" of diagnostic ultrasound should still be kept in mind. This is especially significant with the current rise in the use of endovaginal scanning and pulsed Doppler.

Animals↗
PubMed1999

Receiver psychology and the evolution of multicomponent signals.

Many animals produce and respond to signals made up of multiple components. For example, many avian sexual displays are highly extravagant combinations of visual and acoustic elements, and are described as being 'multicomponent'. One possible reason for the evolution of such complex signals is that they provide more reliable information for receivers. However, receivers also influence signal evolution in another important way, by how they perceive and process signals: signallers will be selected to produce signals that are more easily received. The potential role of receiver psychology in the evolution of multicomponent signals has not previously been considered; in this review I present psychological results that support the notion that two components are better received than one alone. Detection can be improved by producing two components together, thus reducing the reaction time, increasing the probability of detection and lowering the intensity at which detection occurs. Discriminability of multicomponent stimuli is also made easier through better recognition, faster discrimination learning and multidimensional generalization. In addition, multicomponent stimuli also improve associative learning. I show that multicomponency does indeed improve signal reception in receivers, although the benefits of producing components in two sensory modalities (bimodal multicomponent signals) may be larger and more robust than producing them in just one (unimodal multicomponent signals). This highlights the need for consideration of receiver psychology in the evolution of multicomponent signals, and suggests that where signal components do not appear to be informative, they may instead be performing an important psychological function. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗