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At least 1,621 records · Page 90Linked to original sources
PubMed2004

Activation of phasic pontine-wave generator prevents rapid eye movement sleep deprivation-induced learning impairment in the rat: a mechanism for sleep-dependent plasticity.

Animal and human studies of sleep and learning have demonstrated that training on various tasks increases subsequent rapid eye movement (REM) sleep and phasic pontine-wave (P-wave) activity, followed by improvement in performance on the learned task. It is well documented that REM sleep deprivation after learning trials blocks the expected improvement in performance on subsequent retesting. Our aim was to test whether experimentally induced P-wave generator activation could eliminate the learning impairment produced by post-training REM sleep deprivation. Rats were trained on a two-way active avoidance-learning task. Immediately thereafter, two groups of those rats received a control vehicle (100 nl saline) microinjection and one group received a carbachol (50 ng in 100 nl saline) microinjection into the P-wave generator. The carbachol-injected group and one of the two control saline microinjected groups were selectively deprived of REM sleep during a 6 hr polygraphic recording session. All rats were then tested on the avoidance-learning task. The rats that received both the control saline injection and REM sleep deprivation showed learning deficits compared with the control saline-injected rats that were allowed to sleep normally. In contrast, the rats that received the carbachol microinjection and REM sleep deprivation demonstrated normal learning. These results demonstrate, for the first time, that carbachol-induced activation of the P-wave generator prevents the memory-impairing effects of post-training REM sleep deprivation. This evidence supports our hypothesis that the activation of the P-wave generator during REM sleep deprivation enhances a physiological process of memory, which occurs naturally during post-training REM sleep.

Animals↗
PubMed1995

Legionella pneumophila-induced visual learning impairment reversed by anti-interleukin-1 beta.

Infecting mice with the opportunistic intracellular pathogen Legionella pneumophila markedly inhibited place learning of infected C57BL/6 mice as determined by the Morris water maze test. Mice infected with L. pneumophila evinced much less ability to learn the position of a hidden platform than did normal noninfected mice, which quickly learned the location of the hidden platform and escaped from the cool water of the pool with increasing efficiency. However, infected mice treated with anti-interleukin-1 (anti-IL-1) neutralizing antibody learned the task with about the same efficiency as the controls. When the animals were tested 1 week after learning, control animals remembered the task well and were able to escape with near maximal efficacy. On the other hand, L. pneumophila-infected mice performed as poorly after the 1 week rest as during the training period, indicating that infection blocked learning and not merely performance. Mice infected with L. pneumophila and given the antibody treatment were found to be indistinguishable from controls in that they remembered the task and escaped with good efficiency. Thus, the results of this study suggest that the pro-inflammatory cytokine, IL-1 beta, is involved, at least partly, in the attenuation of spatial navigational learning in mice infected acutely with a sublethal concentration of L. pneumophila. These results, therefore, suggest that cognitive impairment of L. pneumophila-infected mice may be related to the cytokine IL-1 beta and, furthermore, that cytokines may be related to learning and memory changes experienced by individuals suffering acute bacterial infections.

Animals↗
PubMed2006

A quantitative assessment of a medicinal chemistry problem-based learning sequence.

OBJECTIVES: To establish an aggressive problem-based learning (PBL) format for the medicinal chemistry course and assess the outcomes of student learning. METHODS: To assess learning in the new format, precourse and postcourse examinations were given to students enrolled before and after problem-based learning was implemented, and appropriate statistical analyses were conducted. RESULTS: The PBL cohort did not learn the same amount of factual content yet performed the same on higher-order thought questions as the non-PBL cohort. CONCLUSIONS: Problem-based learning may not be the ideal method for teaching medicinal chemistry. This may be due to several factors including: student learning type, the lack of a cognitive framework for learning in the basic sciences, and time constraints.

Chemistry, Pharmaceutical↗
PubMed1997

Anosognosia and procedural learning in Alzheimer's disease.

Awareness of cognitive deficits may rely on the implicit learning of intellectual limitations, and anosognosia in Alzheimer's disease (AD) may result from deficits in implicit learning. To examine this hypothesis, a consecutive series of 55 patients with probable AD were divided into groups with mild (n = 13), severe (n = 12), or no anosognosia (n = 30) and were assessed with a neuropsychological battery that included tests of declarative and procedural learning. Whereas there were no significant between-group differences in tests of declarative learning (the Buschke Selective Reminding Test and the Benton Visual Retention Test), patients with severe anosognosia showed a significantly worse performance on procedural learning (as measured with the Maze Learning Test) and a test assessing set shifting abilities (the Wisconsin Card Sorting Test) than AD patients without anosognosia. The authors' results suggest that deficits in procedural learning and anosognosia in AD may result from dysfunction in habit-learning systems.

Aged↗
PubMed2001

Context-specific interference on reversal learning of a stimulus-response habit.

Learning occurs in a particular place and time. In most learning situations, information about the training context is encoded along with the task demands and solution. However, the extent to which context contributes to the acquisition and expression of a particular learned response is unclear. In the present paper we examined two fundamental issues underlying the importance of context information and its role in expression of discrimination learning and reversal learning. Rats were trained on a stimulus-response (S-R) habit task designed for the eight-arm radial maze and after reaching a set criterion different context manipulations were performed. Results from Section 2.2.1 revealed that although rats detected a change in context, the learning was not context specific. Results from Section 2.2.2 showed that S-R reversal learning was enhanced when animals were reversed in a context that was different from the one used during original training. Animals that were reversed in a different context showed a renewal effect to the initial S-R when brought back to the original training context.

Animals↗
PubMed1978

Learning performance varies with brain weight in heterogeneous mouse lines.

Three lines of unselected heterogeneous stocks of mice were tested for learning and activity in active avoidance acquisition and extinction, water-maze discrimination learning and reversal learning, operant discrimination, and passive avoidance acquisition tasks. Ambulation in the open field was also measured. Small to moderate correlations (absolute values of .17 to .42) between brain weight and learning measures were obtained for all tasks except passive avoidance. A moderate correlation between brain weight and activity was found only in the open field (r = .39). Partialing out differences in operant level and body weight and learning performance. When ambulation in the open field was partialed out, however, all correlations between brain weight and learning performance decreased. Previous research has suggested a positive relation between brain weight and learning scores across mammalian orders and species. The results reported here extend this relation to within-species variation in brain size. The results also emphasize the limitations of estimating genetic associations between brain and behavior from comparisons between small numbers of inbred strains or selected lines.

Animals↗
PubMedDate not supplied

How students learn from community-based preceptors.

OBJECTIVE: To explore how students learn in community-based family physicians' offices from the student's point of view. METHOD: Each student completing a community-based family medicine clerkship wrote a "critical incident" narrative about an event that was particularly educational. A coding system was developed by a multidisciplinary research team and thematic analysis was conducted. RESULTS: Critical education experiences were brief, problem-focused, had definitive outcomes, were often collaborative, and led to self-reflection. The most commonly identified mode of learning was "active observation." In most of these situations, the student had significant clinical responsibility, but some involved observation of complex tasks beyond the expectations of a medical student. Most (77%) identified their learning needs after having observed a preceptor, rather than prospectively. Collaboration, coaching, advocacy, and exploring affect were means whereby preceptors and students created a learning environment that students felt was safe, allowed them to recognize their own learning needs, and helped them adopt new behaviors. CONCLUSIONS: These findings broaden the definition of active learning to include active observation and support learner-centered and relational models of learning. Increasing preceptors' awareness of these modes of student learning will enhance the quality of education in ambulatory settings.

Education, Medical, Graduate↗
PubMedDate not supplied

Dyslexia and the learning of a foreign language in school: where are we going?

The difficulties which many dyslexic students encounter in the learning of the English language often extend to the learning of a foreign language in school. Although this problem has been acknowledged for some time, and although the learning of a modern foreign language is a core element in the Scottish curriculum, there has been little research into how modern languages can be presented to offer the best learning opportunities to dyslexic students. Dyslexic students are likely to benefit from a multisensory approach to the learning of a modern foreign language, and it seems likely that they will need to utilize similar strategies to those used for learning their first language. Strategies are discussed with a view to making modern language learning more appropriate for students with difficulties in learning.

Adolescent↗
PubMed2001

Functional networks in motor sequence learning: abnormal topographies in Parkinson's disease.

We examined the neural circuitry underlying the explicit learning of motor sequences in normal subjects and patients with early stage Parkinson's disease (PD) using 15O-water (H2 15O) positron emission tomography (PET) and network analysis. All subjects were scanned while learning motor sequences in a task emphasizing explicit learning, and during a kinematically controlled motor execution reference task. Because different brain networks are thought to subserve target acquisition and retrieval during motor sequence learning, we used separate behavioral indices to quantify these aspects of learning during the PET experiments. In the normal cohort, network analysis of the PET data revealed a significant covariance pattern associated with acquisition performance. This topography was characterized by activations in the left dorsolateral prefrontal cortex (PFdl), rostral supplementary motor area (preSMA), anterior cingulate cortex, and in the left caudate/putamen. A second independent covariance pattern was associated with retrieval performance. This topography was characterized by bilateral activations in the premotor cortex (PMC), and in the right precuneus and posterior parietal cortex. The normal learning-related topographies failed to predict acquisition performance in PD patients and predicted retrieval performance less accurately in the controls. A separate network analysis was performed to identify discrete learning-related topographies in the PD cohort. In PD patients, acquisition performance was associated with a covariance pattern characterized by activations in the left PFdl, ventral prefrontal, and rostral premotor regions, but not in the striatum. Retrieval performance in PD patients was associated with a covariance pattern characterized by activations in the right PFdl, and bilaterally in the PMC, posterior parietal cortex, and precuneus. These results suggest that in early stage PD sequence learning networks are associated with additional cortical activation compensating for abnormalities in basal ganglia function.

Adult↗
PubMed2006

Preclinical Huntington's disease: compensatory brain responses during learning.

Motor sequence learning is abnormal in presymptomatic Huntington's disease (p-HD). The neural substrates underlying this early manifestation of HD are poorly understood. To study the mechanism of this cognitive abnormality in p-HD, we used positron emission tomography to record brain activity during motor sequence learning in these subjects. Eleven p-HD subjects (age, 45.8 +/- 11.0 years; CAG repeat length, 41.6 +/- 1.8) and 11 age-matched control subjects (age, 45.3 +/- 13.4 years) underwent H(2) (15)O positron emission tomography while performing a set of kinematically controlled motor sequence learning and execution tasks. Differences in regional brain activation responses between groups and conditions were assessed. In addition, we identified discrete regions in which learning-related activity correlated with performance. We found that sequence learning was impaired in p-HD subjects despite normal motor performance. In p-HD, activation responses during learning were abnormally increased in the left mediodorsal thalamus and orbitofrontal cortex (OFC; BA 11/47). Impaired learning performance in these subjects was associated with increased activation responses in the precuneus (BA 18/31). These data suggest that enhanced activation of thalamocortical pathways during motor learning can compensate for caudate degeneration in p-HD. Nonetheless, this mechanism may not be sufficient to sustain a normal level of task performance, even during the presymptomatic stage of the disease.

Adult↗
PubMed2003

Early stage Parkinson's disease patients and normal volunteers: comparative mechanisms of sequence learning.

Early-stage nondemented Parkinson's disease (PD(es)) patients can learn short but not long sequences as well as controls. We have previously shown that to achieve normal performance, PD(es) patients activated the same right-sided cortical regions as controls plus the homologous left sided cortex and bilateral cerebellum. In this study, we evaluated two related hypotheses to explain the behavioral abnormalities and the increased bilateral brain activation observed in the PD(es) group. Hypothesis 1 proposed that PD(es) patients recruit regions from a normal bilateral network specialized for sequence learning that healthy controls would activate if performing difficult tasks. Thus, PD(es) patients can learn short sequences as well as controls. Hypothesis 2 proposed that information processing within the network in the PD(es) group is impaired. Thus, PD(es) patients cannot learn as difficult a sequence as controls. To test hypothesis 1, we increased task difficulty and statistical power in the control group and showed that the control and the PD(es) groups activated the same regions. To test hypothesis 2, we analyzed the equal performance data using two partial least squares (PLS) multivariate analyses. The task-PLS analysis showed that to perform equally with controls, the PD(es) group expressed the normal bilateral network more than the control group. The behavior-PLS analysis showed that the correlation between learning performance and regional activation was significantly different between the groups. We conclude that PD(es) patients have near normal learning if task difficulty is moderate because they can recruit additional regions from a normal bilateral network specialized for sequence learning. However, when a difficult task would normally require bilateral activation, PD(es) patients fail to learn because information processing within the network is impaired. Hum. Brain Mapp. 20:246-258, 2003.

Aged↗
PubMed2003

The interaction between cost-management and learning for major surgical procedures - lessons from asymmetric information.

The theory of the learning curve states that learning effects are of particular importance in industries, where human skills play an important role. Consequently, one would expect to find large learning effects for surgical procedures because the physician's experience is quite important for this type of work. For hospitals, there exists indeed a well-documented effect that shows a positive relationship between the number of a certain type of surgery being performed and its resulting quality (volume-outcome relationship). Empirical analyses of the impact of learning on the average cost of a procedure, however, have noted a conspicuous absence of learning effects. Using a mechanism design approach, the paper analyzes a model of quality and cost-management for a hospital, where learning effects are included into the cost function and asymmetric information exists between management and physician. It seeks to answer the question, whether recommendations from a symmetric information scenario with respect to learning carry over to a health care setting, where informational problems tend to be pronounced and severe. If surgery volume interacts with physicians' informational rents, an optimal management reaction to the presence of learning may result in a policy, which is the exact opposite of the one under symmetric information.

Clinical Competence↗
PubMed2001

Preserved implicit learning on both the serial reaction time task and artificial grammar in patients with Parkinson's disease.

Thirteen nondemented patients with Parkinson's disease (PD) were compared with age-matched controls on two standard tests of implicit learning. A verbal version of the Serial Reaction Time (SRT) task was used to assess sequence learning and an artificial grammar (AG) task assessed perceptual learning. It was predicted that PD patients would show implicit learning on the AG task but not the SRT task, as motor sequence learning is thought to be reliant on the basal ganglia, which is damaged in PD. Patients with PD demonstrated implicit learning on both tasks. In light of these unexpected results the research on SRT learning in PD is reconsidered, and some possible explanations for the sometimes conflicting results of PD patient samples on the SRT task are considered. Four factors which merit further study in this regard are the degree to which the SRT task relies on overt motor responses, the effects of frontal lobe dysfunction upon implicit sequence learning, the effects of cerebellar degeneration, and the degree to which the illness itself has advanced.

Adult↗
PubMed1998

Induction of relational schemas: common processes in reasoning and complex learning.

Five experiments were performed to test whether participants induced a coherent representation of the structure of a task, called a relational schema, from specific instances. Properties of a relational schema include: An explicit symbol for a relation, a binding that preserves the truth of a relation, potential for higher-order relations, omnidirectional access, potential for transfer between isomorphs, and ability to predict unseen items in isomorphic problems. However relational schemas are not necessarily coded in abstract form. Predictions from relational schema theory were contrasted with predictions from configural learning and other nonstructural theories in five experiments in which participants were taught a structure comprised of a set of initial-state,operator-->end-state instances. The initial-state,operator pairs were presented and participants had to predict the correct end-state. Induction of a relational schema was achieved efficiently by adult participants as indicated by ability to predict items of a new isomorphic problem. The relational schemas induced showed the omnidirectional access property, there was efficient transfer to isomorphs, and structural coherence had a powerful effect on learning. The "learning to learn" effect traditionally associated with the learning set literature was observed, and the long-standing enigma of learning set acquisition is explained by a model composed of relational schema induction and structure mapping. Performance was better after reversal of operators than after shift to an alternate structure, even though the latter entailed more overlap with previously learned tasks in terms of the number of configural associations that were preserved. An explanation for the reversal shift phenomenon in terms of induction and mapping of a relational schema is proposed. The five experiments provided evidence supporting predictions from relational schema theory, and no evidence was found for configural or nonstructural learning theories.

Adult↗
PubMed1985

Visual discrimination learning and interhemispheric transfer in the cat, as affected by 6-hydroxydopamine.

Learning and interhemispheric transfer of visual flux, pattern and form discriminations were studied in the cat after selected exposure of one suprasylvian cortex to 6-hydroxydopamine (6-OHDA). Biochemical assay using High Performance Liquid Chromatography (HPLC) two weeks after 6-OHDA revealed no discernible norepinephrine or dopamine in the treated cortex, but elevated concentrations of these transmitters in the cortex of the opposite hemisphere. Visual discriminations learned before treatment with 6-OHDA were retained at a high level using either the eye on the side of chemical lesion or the eye on the untreated side. An asymmetric deficit in learning new form discriminations was present, however, when the eye on the untreated side was used, in contrast to normal learning using the eye on the side of the hemisphere with depleted adrenergic nerve supply. Once learning was achieved using the lesioned hemisphere transfer of the engram was found to the untreated hemisphere. Thus, the unlesioned hemisphere was unable to learn normally using direct retinal input from the ipsilateral eye, but showed good capacity for learning using indirect visual input from the contralateral eye. This suggests a powerful influence of the callosum on the learning abilities of the two hemispheres, an influence proved by sectioning the callosum. Callosotomy resulted in a reversal of the discriminative capacities seen after 6-OHDA, i.e. the lesioned hemisphere was defective relative to the unlesioned hemisphere.

Animals↗
PubMed1994

The impact of motor responses on serial-pattern learning.

Subjects are able to learn even very complex serial patterns in serial-reaction-time tasks. The investigation of the learning processes behind this phenomenon has yielded contradictory results. Some studies have come to the conclusion the subjects had learned the sequence of stimuli. Other studies have assumed that the sequence of responses had been learned or a combination of both stimuli and responses. The present experiments stress the impact of motor responses on serial-pattern learning. The subjects had to respond to serial targets that were presented within a matrix of distractors. The position of each target could be predicted from the identity and position of the previous target. If the subjects were to learn this pattern, they would be able to speed up the search for the target and give faster responses. The results indicated that the relation between the target identity and the position of the next target was acquired much better by those subjects who had to respond to each target with a special motor response. If the same response was required for the relevant targets, knowledge of the rule was somewhat fragmentary. To explain these results, mechanisms of motor learning and motor planning are discussed. It is assumed that learning of the rules occurs if the position changes appear to be effects of different motor responses.

Adult↗
PubMedDate not supplied

The effects of intrahippocampal BDNF and NGF on spatial learning in aged Long Evans rats.

Spatial learning rate was compared in cognitively impaired aged rats infused with either brain-derived neurotrophic factor (BDNF) or nerve growth factor (NGF). BDNF or NGF was infused into the dorsal hippocampus/third ventricle while animals were being trained on the Morris water maze. Training continued until all rats met a spatial learning criterion. Seven weeks later, they were tested for retention of the task, and sacrificed for assessment of hippocampal high-affinity choline uptake (HACU) or hypothalamic biogenic amine levels. NGF, but not BDNF, improved spatial learning rate in aged rats and increased hippocampal choline uptake weeks after withdrawal of NGF. Although BDNF did not improve spatial learning, it did induce a partial, long-term normalization of the elevated hypothalamic 5-HT levels observed in our aged rats. These data suggest that (1) intrahippocampal/intraventricular infusion of NGF can improve the learning rate of aged, spatial learning-impaired rats, and that this improvement in acquisition could be associated with increased hippocampal cholinergic activity, and (2) that the BDNF-induced normalization of hypothalamic 5-HT levels in aged rats was not sufficient to improve learning rate in aged, spatial learning-impaired rats.

Aging↗
PubMed2005

Effect of serotonin depletion on 5-HT2A-mediated learning in the rabbit: evidence for constitutive activity of the 5-HT2A receptor in vivo.

RATIONALE: Associative learning during Pavlovian eyeblink conditioning has been shown to be regulated by 5-HT2A receptors. The existence of inverse agonists that retard learning through an action at the 5-HT2A receptor suggests the existence of constitutive activity at that receptor and that depletion of serotonin should have minimal effects on learning. OBJECTIVES: We examined whether depletion of serotonin would impair trace eyeblink conditioning or the enhancement of conditioning produced by the agonist lysergic acid diethylamide (LSD) and the retardation of conditioning produced by the inverse agonist MDL11,939. METHODS: Animals received bilateral intraventricular injections of 5,7-dihydroxytryptamine (5,7-DHT) at doses of 760 or 1,140 microg/side (1.88 or 2.82 micromol/side) and were later exposed to eight daily conditioning sessions. RESULTS: Serotonin depletion produced by the lower dose of 5,7-DHT was 71 and 72% in cortex and hippocampus, respectively, with no change in 5-HT2A receptor density, no effect on learning, and no effect on the ability of LSD to enhance and MDL11,939 to retard learning. The higher dose of 5,7-DHT produced serotonin decreases of 85 and 90% in cortex and hippocampus, respectively, accompanied by a 96% decrease in the density of the serotonin transporter, but no significant effect on learning. CONCLUSIONS: Pavlovian trace eyeblink conditioning is regulated predominantly by the constitutive activity of the 5-HT2A receptor rather than by serotonin release onto the receptor during learning. It was suggested that the 5-HT2A receptor regulates learning by modulating the release of dopamine, acetylcholine, and glutamate, transmitters known to affect eyeblink conditioning.

5,7-Dihydroxytryptamine↗