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At least 1,711 records · Page 95Linked to original sources
PubMed1998

Molecular manipulations of extracellular superoxide dismutase: functional importance for learning.

Extracellular superoxide dismutase (EC-SOD) controls the availability of extracellular superoxide (O2.-), which is important for a variety of physiological pathways, including the primary means of inactivating nitric oxide (NO). The role of EC-SOD in neurobehavioral function has been until now unexplored. In the current studies, the phenotypic expression of genotypic alterations of EC-SOD production in mice were characterized for spatial learning and memory. Dramatic impairments in spatial learning in the win-shift 8-arm radial maze were seen in both EC-SOD knockout mice and EC-SOD overexpressing mice. The EC-SOD overexpressing mice were further characterized as having significant deficits in a repeated acquisition task in the radial-arm maze, which permitted the dissociation of long and short-term learning. Long-term learning was significantly impared by EC-SOD overexpression, whereas short-term learning was not significantly affected by EC-SOD overexpression. No systems have been shown to be importantly involved in learning and memory. This may be important in the current studies because EC-SOD has primary control over the inactivation of NO. We found that EC-SOD overexpressing mice were resistant to the cognitive effects of L-NAME (NG-nitro-L-arginine methyl ester hydrochloride), an NO synthase inhibitor. Decreased NO catabolism in these mice may have served to counter the effects of NOS inhibition by L-NAME. The current finding that EC-SOD levels that were either higher or lower than controls impaired learning demonstrates that the proper control of brain extracellular O2.- may be more vital than merely reduction of brain extracellular O2.- in maintaining adequate learning function.

Animals↗
PubMed1992

Predictive and diagnostic learning within causal models: asymmetries in cue competition.

Several researchers have recently claimed that higher order types of learning, such as categorization and causal induction, can be reduced to lower order associative learning. These claims are based in part on reports of cue competition in higher order learning, apparently analogous to blocking in classical conditioning. Three experiments are reported in which subjects had to learn to respond on the basis of cues that were defined either as possible causes of a common effect (predictive learning) or as possible effects of a common cause (diagnostic learning). The results indicate that diagnostic and predictive reasoning, far from being identical as predicted by associationistic models, are not even symmetrical. Although cue competition occurs among multiple possible causes during predictive learning, multiple possible effects need not compete during diagnostic learning. The results favor a causal-model theory.

Adult↗
PubMed1999

The relationship between skill learning and repetition priming: experimental and computational analyses.

Skill learning and repetition priming are considered by some to be supported by separate memory systems. The authors examined the relationship between skill learning and priming in 3 experiments using a digit entering task, in which participants were presented with unique and repeated 5-digit strings with controlled sequential structure. Both skill learning and priming were observed across a wide range of skill levels. Performance reflected the effects of learning at 3 different levels of stimulus structure, calling into question a binary dichotomy between item-specific priming and general skill learning. Two computational models were developed which demonstrated that previous dissociations between skill learning and priming can occur within a single memory system. The experimental and computational results are interpreted as suggesting that skill learning and priming should be viewed as 2 aspects of a single incremental learning mechanism.

Adult↗
PubMed1987

Cholinergic neurons, learning, and recovery of function.

Two experiments were designed to examine the role of the cholinergic septo-hippocampal projection in spatial and nonspatial learning processes. In Experiment 1 the interaction of individual learning strategies and recovery of function was investigated following medial septal lesions, by assessing individual learning styles and number of trials to recovery on a standard radial eight-arm-maze task. Experiment 2 addressed the relevance of the cholinergic septo-hippocampal pathway in the acquisition of spatially mediated behavior, by employing medial septal lesions, prior to acquisition learning of a modified version of the radial eight-arm-maze task. The data from these two experiments demonstrated that (a) the cholinergic septo-hippocampal projection is important for the acquisition and maintenance of spatial learning strategies, (b) loss of cholinergic function leads to alteration of learning strategies, (c) different learning strategies can be employed to acquire the same behaviors, and (d) the rate of recovery following brain injury can be influenced by preoperative learning strategies.

Animals↗
PubMed1999

Olfactory associative learning in Caenorhabditis elegans is impaired in lrn-1 and lrn-2 mutants.

The C. elegans mutants, lrn-1 and lrn-2, are impaired in associative learning using conditioned taste cues. Both mutants are defective in associative learning about appetitive and aversive events, indicating that lrn-1 and lrn-2 exert effects across motivational boundaries. In a new olfactory associative learning paradigm, in which wild type worms learn to avoid a previously attractive diacetyl odor after it has been paired with an aversive acetic acid solution, lrn-1 and lrn-2 are impaired. Although defective in associative learning using a conditioned olfactory cue, nonassociative learning (habituation and dishabituation) using this same olfactory cue is unaffected. The discovery that lrn-1 and lrn-2 are defective in associative learning with both taste and olfactory cues may suggest that associative learning in different sensory modalities converges on a common genetic pathway in C. elegans that is subserved by lrn-1 and lrn-2.

Animals↗
PubMed1997

Cognitive-motor learning in Parkinson's disease.

Procedural learning deficits are common in Parkinson's disease (PD), but contradictory results have been reported in rotary pursuit learning. This article compared rotary pursuit learning in 2 nondemented PD groups and 2 normal control (NC) groups, using a between-subjects group design in which 3 rotation speeds were presented either randomly or in blocks. The pattern of learning differed between the randomized and the blocked conditions in the NC, but not in the PD groups. Learning was impaired in the PD group in the random condition only. Memory, visuospatial, or executive skills were not associated with the PD group's poorer learning in the randomized context. Results show that procedural learning deficits are not universal with basal ganglia abnormalities but rather depend on the specific cognitive requirements of the learning context.

Aged↗
PubMed2003

The relative strengths of indirect and direct word learning.

Indirect word learning lacks many of the overt social-pragmatic cues to reference available in direct word learning, yet the two result in equally robust mappings when comprehension is assessed immediately after learning. The 3 studies reported here investigated how 3-year-olds (N=96) respond to more challenging tests of the relative strengths of indirect and direct word learning. In Study 1, children's comprehension of indirectly and directly learned proper and common names was tested after a 2-day delay. Both types of learning resulted in proper name mappings that picked out an individual and in common name mappings that could be extended to another category member. In Studies 2 and 3, children's comprehension was tested after they had been provided with additional, and sometimes inconsistent, information about the scope of previously learned words. There was a hint of a difference between indirect and direct word learning. but results overall suggested that the two were equivalent.

Attention↗
PubMed2007

Within-category discontinuity interacts with verbal rule complexity in perceptual category learning.

A test of the predicted interaction between within-category discontinuity and verbal rule complexity on information-integration and rule-based category learning was conducted. Within-category discontinuity adversely affected information-integration category learning but not rule-based category learning. Model-based analyses suggested that some information-integration participants improved performance by recruiting more "units" in the discontinuous condition. Verbal rule complexity adversely affected rule-based category learning but not information-integration category learning. Model-based analyses suggested that the rule based effect was on both decision criterion learning and variability in decision criterion placement. These results suggest that within-category discontinuity and decision rule complexity differentially impact information-integration and rule-based category learning and provide information regarding the detailed processing characteristics of these two proposed category learning systems.

Concept Formation↗
PubMed2004

Learning and retrieval of concurrently presented spatial discrimination tasks: role of the fornix.

In macaque monkeys (Macaco mulatta), memory for scenes presented on touch screens is fornix dependent. However, scene learning is not a purely spatial task, and existing direct evidence for a fornix role in spatial memory comes exclusively from tasks involving learning about food-reward locations. Here the authors demonstrate that fornix transection impairs learning about spatial stimuli presented on touch screens. Using a new concurrent spatial discrimination learning task, they found that fornix transection did not impair recall of preoperatively learned problems. Relearning, on the other hand, was mildly impaired, and new learning was strongly impaired. New learning of smaller sets of harder problems was also markedly impaired, as was spatial configured learning. This pattern supports a functional specialization according to stimulus domain in the medial temporal lobe.

Animals↗
PubMed2005

Espresso reward learning, hold the dopamine: theoretical comment on Robinson et al. (2005).

QUESTION: Is dopamine needed for reward learning? ANSWER: No--at least, not in the brain of a caffeinated dopamine-deficient (DD) mutant mouse. That is the conclusion of an important paper in this issue by S. Robinson, S. M. Sandstrom, V. H. Denenberg, and R. D. Palmiter (see record 2005-01705-001). Those authors demonstrate that reward learning can proceed normally in the brains of DD mice, even though they contain no dopamine at the time of learning, if the mice are given caffeine just before learning. Caffeine activates the DD mice by a nondopaminergic mechanism, allowing them to learn where to obtain food reward in a T-maze runway. Their reward-learning-without-dopamine is revealed on a subsequent test day, when dopamine function is restored by L-dopa administration. Robinson et al. conclude that dopamine is not needed for normal learning about rewards, or for hedonic "liking" of rewards during learning, but rather specifically for a motivational "wanting" component of reward, such as incentive salience.

Animals↗
PubMed2006

Place learning strategy of substantia nigra pars compacta-lesioned rats.

The substantia nigra pars compacta (SNc) and the dorsal striatum are often considered to be necessary for stimulus-response (S-R) habit learning, whereas the dorsal hippocampus is considered to be necessary for relational (declarative) memory. Spatial learning is a kind of relational learning that occurs when a rat is released from different locations (variable start) in a water maze to find a submerged platform that is kept in a constant location. However, when the rat is always released from the same starting position (constant start), it can learn to find the platform oriented by a fixed configuration of cues, that is, by S-R learning. To test the critical role of the SNc in S-R and relational learning, the authors tested adult male Wistar rats, sham-operated or with a lesion in the SNc, in these 2 versions of the water maze task. The SNc lesion was induced by bilateral intranigral infusion of 0.5 micromol 1-methyl-4-phenyl- 1,2,3,6-tetrahydropyridine. Although the SNc-lesioned rats learned the variable-start version as effectively as sham rats did, they were significantly impaired in learning the constant-start version of the task.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2002

Protein phosphatase 1 is a molecular constraint on learning and memory.

Repetition in learning is a prerequisite for the formation of accurate and long-lasting memory. Practice is most effective when widely distributed over time, rather than when closely spaced or massed. But even after efficient learning, most memories dissipate with time unless frequently used. The molecular mechanisms of these time-dependent constraints on learning and memory are unknown. Here we show that protein phosphatase 1 (PP1) determines the efficacy of learning and memory by limiting acquisition and favouring memory decline. When PP1 is genetically inhibited during learning, short intervals between training episodes are sufficient for optimal performance. The enhanced learning correlates with increased phosphorylation of cyclic AMP-dependent response element binding (CREB) protein, of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and of the GluR1 subunit of the AMPA receptor; it also correlates with CREB-dependent gene expression that, in control mice, occurs only with widely distributed training. Inhibition of PP1 prolongs memory when induced after learning, suggesting that PP1 also promotes forgetting. This property may account for ageing-related cognitive decay, as old mutant animals had preserved memory. Our findings emphasize the physiological importance of PP1 as a suppressor of learning and memory, and as a potential mediator of cognitive decline during ageing.

Aging↗
PubMed2006

Differentiating phonotactic probability and neighborhood density in adult word learning.

PURPOSE: The purpose of this study was to differentiate effects of phonotactic probability, the likelihood of occurrence of a sound sequence, and neighborhood density, the number of words that sound similar to a given word, on adult word learning. A second purpose was to determine what aspect of word learning (viz., triggering learning, formation of an initial representation, or integration with existing representations) was influenced by each variable. METHOD: Thirty-two adults were exposed to 16 nonwords paired with novel objects in a story context. The nonwords orthogonally varied in phonotactic probability and neighborhood density. Learning was measured following 1, 4, and 7 exposures in a picture-naming task. Partially correct (i.e., 2 of 3 phonemes correct) and completely correct responses (i.e., 3 of 3 phonemes correct) were analyzed together and independently to examine emerging and partial representations of new words versus complete and accurate representations of new words. RESULTS: Analysis of partially correct and completely correct responses combined showed that adults learned a lower proportion of high-probability nonwords than low-probability nonwords (i.e., high-probability disadvantage) and learned a higher proportion of high-density nonwords than low-density nonwords (i.e., high-density advantage). Separate analysis of partially correct responses yielded an effect of phonotactic probability only, whereas analysis of completely correct responses yielded an effect of neighborhood density only. CONCLUSIONS: These findings suggest that phonological and lexical processing influence different aspects of word learning. In particular, phonotactic probability may aid in triggering new learning, whereas neighborhood density may influence the integration of new lexical representations with existing representations.

Adolescent↗
PubMed1997

Using a phenomenological research technique to examine student nurses' understandings of experiential teaching and learning: a critical review of methodological issues.

This paper provides a report of the usage of a phenomenological research methodology to investigate the influence on clinical practice of pre- and post-registration nurse education which makes explicit use of experiential teaching and learning approaches. The primary aim of the research was to explore the use of a phenomenological research methodology to examine the students' understanding of experiential teaching and learning. The claims made for the use of experiential teaching and learning approaches in both pre- and post-registration nurse courses and how clinical practice is influenced by the experiential learning elements of pre- and post-registration nurse education were also examined. The first stage of the enquiry involved focused non-directive interviews with members of BSc Nursing Studies and MSc Mental Health Branch programmes. Both programmes claim to make use of experiential teaching and learning. The data were analysed using a technique developed by Giorgi. Previous experiences of experiential teaching and learning were probed, student interpretations differentiated, and the relationship between course-based learning using experiential approaches and the implications for it's influence on practice were examined. The second stage of the enquiry has followed up the initial findings, exploring the students' experience of experiential approaches on their courses both in the classroom and in work-based learning situations. The findings are presented and discussed in the context of other studies from both nurse and higher education. Throughout the paper methodological concerns arising are discussed. The paper concludes with the identification of methodological problems arising from the research strategy: the implications of the power nexus created when teachers research students, and issues relating to the use of a phenomenological methodology in a longitudinal study.

Clinical Competence↗
PubMed2001

Problem-based learning in a new Canadian curriculum.

Problem-based learning (PBL) is a method of group learning that uses true-to-life problems as a stimulus for students to learn problem-solving skills and acquire knowledge about the basic and clinical sciences. This article documents the design and implementation of PBL in a second year course in the new curriculum of the University of Ottawa School of Nursing's Generic Program. The learning and teaching experiences of students and facilitators in this PBL course are described. As a way to determine students' perception of their learning using PBL, they were asked to respond to four questions. The most frequently described thinking processes were problem solving, nursing process and group process. When asked to describe the learning they derived from PBL, as differentiated from other instructional methods, students identified group process and problem solving most often. The most frequently identified factors that influenced performance and learning in PBL were positive attitude and group effort. The factors that affected the facilitators' performance of their role were large group size, insufficient practice of facilitator skills and PBL preparation. To enhance group process, facilitators modelled and shared roles. They fostered student motivation and development through formative evaluation. PBL produced clear benefits for students, such as increased autonomous learning, critical thinking, problem solving and communication. For facilitators, PBL was a liberation from the traditional role of 'content expert and super consultant'.

Communication↗
PubMed2001

Developing critical reflection for professional practice through problem-based learning.

AIMS: To explore the influence of current learning traditions in nursing on the development of reflection and critical reflection as professional practice skills and to offer suggestions for nursing education that will specifically facilitate the development of critical reflection. ORGANIZATIONAL CONSTRUCTS: Mezirow's transformative learning theory, Barrows conceptualization of problem-based learning (PBL). METHODS: Integrative literature review of published literature related to nursing, health science education and professional education from 1983-2000. FINDINGS: Professional education scholars concur that specialized knowledge is clearly essential for professional practice, however, they also suggest that self-consciousness (reflection) and continual self-critique (critical reflection) are crucial to continued competence. While strategies to facilitate reflection have been outlined in the literature, specific strategies to facilitate the development of critical reflection and implications for nursing education are much less clear. Advocates of reflective and critically reflective practice suggest that the development of these abilities should be inextricably linked to professional development and can be developed through active repeated guided practice. In health care, PBL based on constructivism, has been identified as one way to facilitate the development of these skills. CONCLUSIONS: Nursing learners exposed to PBL develop the ability to be reflective and critically reflective in their learning and acquire the knowledge and skill within the discipline of nursing by encountering key professional practice situations as the stimulus and focus of their classroom learning. The learners' ability to be both reflective and critically reflective in their learning is developed by critical questioning of the faculty tutor during situational analysis, learning need determination, application of knowledge, critique of resources and personal problem-solving processes, and summarization of what was learned.

Education, Nursing↗
PubMed1998

The NHS as a learning organization: aspirations beyond the rainbow?

AIM: It is the intention of this paper to review the issues and challenges organizations face when aspiring to embrace and enact the tenets of a learning organization; and in particular the perceived impact on management strategy, structure and leadership styles. The paper is predicated on the premise that learning and knowledge act as vital strategic resources, crucial not only to organizations in terms of competitive advantage but to ethical enterprise per se. BACKGROUND: Modern life is characterized by change, against the backdrop of this continual turmoil, organizational learning has emerged as a dominant theme within contemporary management theory, with many commentators increasingly locating the capacity of an aspiring organization to accommodate the ethos of organizational learning, as the vital component in ensuring enduring efficiency, innovation and competitiveness. However, the utility of such learning needs to be scrutinized and evaluated in terms of service need and expectation. ORIGINS OF INFORMATION: The paper will expand upon wider theoretical debates extant within the literature, by considering the concept and utility of the learning organization with specific reference to management reform extant within the British National Health Service (NHS). DATA ANALYSIS: During the course of the review the various the theoretical positions contributing to the notion of the learning organization will be analysed, the practical ramifications of which will be examined in the context of reflective practice, clinical supervision and the wider cultural background of nursing and the NHS. CONCLUSIONS: The paper concludes that the NHS needs to reorientate management perspectives to focus attention more acutely on systems which are deliberately designed to facilitate shared learning, to unravel the ambiguities of organizational life, to affirm management belief in the nursing contribution and to achieve an as yet unrealized potential in terms of patient care and advanced nursing practice.

Clinical Competence↗
PubMed2001

Neurodevelopmental and behavioural characteristics in learning disabilities and attention deficit disorder.

Specific learning disability in childhood is frequently associated with attention deficit disorder. The distinction between children with and without such comorbidity is often difficult to make. Our aim was to delineate the neurocognitive and behavioural differences between children with specific learning disabilities, with and without attention deficit. Students diagnosed with learning disability, mean age 8.3, 1.4 SD (N-50), and students with learning disability and attention deficit disorder, mean age 8.7, 1.4 SD (N-50), were assessed. The Paediatric Early Elementary Examination and the Aggregate Neurobehavioural Student Health Education Review were administered and their scores as well as pattern of correlations within and between domains were analysed. Only few differences in neurocognitive functions between these groups were evident. Most neurocognitive domains were similarly intercorrelated in the two groups. However, recall was correlated with other neurocognitive domains only among the children with learning and attention deficits. A proportion of significant correlations between neurocognitive and behavioural domains was found among the children with learning disability and attention deficit disorder, but not among the children with learning disability only. It appears that while neurocognitive profiles are similar in these two groups, their interrelationship with behavioural patterns differ. These findings give support to the neurological origin of attention deficit disorder related behaviours among learning disabled children. Different interventions should therefore be considered for each of these entities.

Attention Deficit Disorder with Hyperactivity↗