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At least 1,603 records · Page 89Linked to original sources
PubMed1999

Local inhibition of hippocampal nitric oxide synthase does not impair place learning in the Morris water escape task in rats.

Recent studies have provided evidence that nitric oxide (NO) has a role in certain forms of memory formation. Spatial learning is one of the cognitive abilities that has been found to be impaired after systemic administration of an NO-synthase inhibitor. As the hippocampus has a pivotal role in spatial orientation, the present study examined the role of hippocampal NO in spatial learning and reversal learning in a Morris task in adult rats. It was found that N omega-nitro-L-arginine infusions into the dorsal hippocampus affected the manner in which the rats were searching the submerged platform during training, but did not affect the efficiency to find the spatial location of the escape platform. Hippocampal NO-synthase inhibition did not affect the learning of a new platform position in the same water tank (i.e. reversal learning). Moreover, no treatment effects were observed in the probe trials (i.e. after acquisition and after reversal learning), indicating that the rats treated with N omega-nitro-L-arginine had learned the spatial location of the platform. These findings were obtained under conditions where the NO synthesis in the dorsal hippocampus was completely inhibited. On the basis of the present data it was concluded that hippocampal NO is not critically involved in place learning in rats.

Animals↗
PubMed2002

Impaired spatial and sequential learning in rats treated neonatally with D-fenfluramine.

D-Fenfluramine, a serotonin releaser, was administered to neonatal rats on postnatal days 11-20 (a stage of hippocampal development analogous to third trimester human ontogeny). As adults, the D-fenfluramine-treated offspring exhibited dose-related impairments of sequential and spatial learning and reference memory in the absence of sensorimotor impairments. Procedures to minimize stress and to control for other performance effects prior to testing for spatial learning demonstrated that nonspecific factors did not account for the selective effects of D-fenfluramine on learning and memory. Developmental D-fenfluramine-induced spatial and sequential learning deficits are similar to previous findings with developmental MDMA treatment. By contrast, recent findings with developmental D-methamphetamine treatment showed spatial learning deficits while sparing sequential learning. The spatial learning effects common to all three drugs suggest that they may share a common mechanism of action, however, the effects are not related to long-lasting changes in hippocampal 5-HT levels as no differences were found in adulthood. Whether the cognitive deficits are related to the effects of substituted amphetamines on corticosteroids, other aspects of the 5-HT system, or some unidentified neuronal substrates is not known, but the data demonstrate that these drugs are all capable of inducing long-term adverse effects on learning.

Animals↗
PubMed2003

Impairment of reward-related learning by cholinergic cell ablation in the striatum.

The striatum in the basal ganglia-thalamocortical circuitry is a key neural substrate that is implicated in motor balance and procedural learning. The projection neurons in the striatum are dynamically modulated by nigrostriatal dopaminergic input and intrastriatal cholinergic input. The role of intrastriatal acetylcholine (ACh) in learning behaviors, however, remains to be fully clarified. In this investigation, we examine the involvement of intrastriatal ACh in different categories of learning by selectively ablating the striatal cholinergic neurons with use of immunotoxin-mediated cell targeting. We show that selective ablation of cholinergic neurons in the striatum impairs procedural learning in the tone-cued T-maze memory task. Spatial delayed alternation in the T-maze learning test is also impaired by cholinergic cell elimination. In contrast, the deficit in striatal ACh transmission has no effect on motor learning in the rota-rod test or spatial learning in the Morris water-maze test or on contextual- and tone-cued conditioning fear responses. We also report that cholinergic cell elimination adaptively up-regulates nicotinic ACh receptors not only within the striatum but also in the cerebral cortex and substantia nigra. The present investigation indicates that cholinergic modulation in the local striatal circuit plays a pivotal role in regulation of neural circuitry involving reward-related procedural learning and working memory.

Acetylcholine↗
PubMed1998

Effect of reduced myristoylated alanine-rich C kinase substrate expression on hippocampal mossy fiber development and spatial learning in mutant mice: transgenic rescue and interactions with gene background.

The myristoylated alanine-rich C kinase substrate (MARCKS) is a prominent protein kinase C (PKC) substrate in brain that is expressed highly in hippocampal granule cells and their axons, the mossy fibers. Here, we examined hippocampal infrapyramidal mossy fiber (IP-MF) limb length and spatial learning in heterozygous Macs mutant mice that exhibit an approximately 50% reduction in MARCKS expression relative to wild-type controls. On a 129B6(N3) background, the Macs mutation produced IP-MF hyperplasia, a significant increase in hippocampal PKCepsilon expression, and proficient spatial learning relative to wild-type controls. However, wild-type 129B6(N3) mice exhibited phenotypic characteristics resembling inbred 129Sv mice, including IP-MF hypoplasia relative to inbred C57BL/6J mice and impaired spatial-reversal learning, suggesting a significant contribution of 129Sv background genes to wild-type and possibly mutant phenotypes. Indeed, when these mice were backcrossed with inbred C57BL/6J mice for nine generations to reduce 129Sv background genes, the Macs mutation did not effect IP-MF length or hippocampal PKCepsilon expression and impaired spatial learning relative to wild-type controls, which now showed proficient spatial learning. Moreover, in a different strain (B6SJL(N1), the Macs mutation also produced a significant impairment in spatial learning that was reversed by transgenic expression of MARCKS. Collectively, these data indicate that the heterozygous Macs mutation modifies the expression of linked 129Sv gene(s), affecting hippocampal mossy fiber development and spatial learning performance, and that MARCKS plays a significant role in spatial learning processes.

Animals↗
PubMed2004

A blueprint for interprofessional learning.

Interprofessional education (IPE) has been promoted as a method to enhance the ability of health professionals to learn to work together. This article examines several approaches to learning that can help IPE fulfill its expectations. The first is aimed at the transfer of learning novel situations and involves two ideas. Students need to be challenged with progressively more complex tasks and those tasks need to reflect the reality in which they will be working. Second, the learning situation needs to be structured using the five elements of best-practice cooperative learning: positive interdependence, face-to-face promotive interaction, individual accountability, interpersonal and small-group skills, and group processing. Finally, the learning process itself needs to be approached from an experiential learning framework cycling through the four-stage model of planning, doing, observing and reflecting. By using increasingly complex and relevant cases in cooperative groups with an experiential learning process interprofessional education can be successful.

Cooperative Behavior↗
PubMed2005

Starting learning in medical practice: an evaluation of a new Introductory Clerkship.

The transition from undergraduate medical education to learning in clinical clerkships can be difficult for students. Learning in clinical practice requires awareness of learning opportunities and goals, active elaboration and reflection. Staff should provide students with guidance to learn from their experiences. A new Introductory Clerkship was designed to facilitate the start of goal-oriented, active and reflective work-based learning. This four-week clerkship is a result of the cooperation of six major specialties in the university hospital. The innovations included explicitly formulated goals, a description of the student's activities in daily practice and of the staff's role, group meetings, a logbook, a halfway formative interview and a final summative interview. The aim of this study was to investigate to what extent the innovations of the new Introductory Clerkship were implemented and how students and residents valued them. Two questionnaires were constructed: one was administered to students (n = 54) and the other to residents (n = 27). Students considered participation in daily practice very instructive, although more observations of history taking and physical examination are wanted. The interviews and group meetings promote students' learning. Use of the logbook needs improvement. Residents perceived a shortage of time and would appreciate more participation of staff members, as well as a better preparation for supervising tasks. Overall, the study demonstrates that it is possible to introduce innovations in clinical clerkships to improve the learning environment of work-based learning.

Attitude of Health Personnel↗
PubMed2005

A blueprint for interprofessional learning.

Interprofessional education (IPE) has been promoted as a method to enhance the ability of health professionals to learn to work together. This article examines several approaches to learning that can help IPE fulfill its expectations. The first is aimed at the transfer of learning novel situations and involves two ideas. Students need to be challenged with progressively more complex tasks and those tasks need to reflect the reality in which they will be working. Second, the learning situation needs to be structured using the five elements of best-practice cooperative learning: positive interdependence, face-to-face promotive interaction, individual accountability, interpersonal and small-group skills, and group processing. Finally, the learning process itself needs to be approached from an experiential learning framework cycling through the four-stage model of planning, doing, observing and reflecting. By using increasingly complex and relevant cases in cooperative groups with an experiential learning process interprofessional education can be successful.

Canada↗
PubMed1997

Baseline performance and learning rate of procedural and declarative memory tasks: younger versus older adults.

Twenty-five older and 25 younger adults were compared on declarative (i.e., Rey Auditory-Verbal Learning Test and Visual Pair Associations) and procedural (i.e., Tower of Hanoi puzzle and Porteus mazes) learning tasks. A dissociation between learning rate on declarative and procedural tasks was demonstrated for the elderly participants. The younger group showed a steeper learning rate than the older group on the declarative tasks. By contrast, the learning rate of both groups on the procedural tasks did not differ consistently, whether the measure was number of errors/moves or time elapsed (with one exception in which the older group showed a steeper learning rate than the younger group). The younger group's baseline performance was better than that of the older group on all tasks employed in this study. These results reinforce the importance of distinguishing between baseline performance and the rate of learning on procedural learning tasks.

Adult↗
PubMed1993

Does nitrous oxide antagonize isoflurane-induced suppression of learning?

BACKGROUND: A greater MAC fraction of nitrous oxide than isoflurane is required to prevent response to verbal commands and suppress the capacity to learn. Speculating that this difference between these agents may be caused by nitrous oxide's capacity to increase sympathetic activity, we tested the hypothesis that nitrous oxide may antagonize the suppression of learning found with isoflurane. METHODS: We administered a combination of isoflurane and nitrous oxide at three subanesthetic test concentrations (0.43, 0.56, and 0.68 MAC) to 24 healthy male volunteers. Assuming additivity of the anesthetics, the first test concentration was selected to suppress learning of new information by 50% (ED50 for suppression of learning); the second concentration, to suppress the ability to respond appropriately to verbal command by 50% (MAC-awake); and the third, to provide 1.4 times MAC-awake. Three tests of learning were applied. At each test concentration, we provided 7 answers to "trivial pursuit"-type questions, resulting in a set of 21 answered questions for each volunteer; an additional 7 unanswered questions served as controls. At the highest test concentration, each volunteer also heard two examples from each of two categories (4 words) repeated 30 times (the category-example task), and a message instructing them to touch either their nose or their ear during a specified interval in the postanesthetic interview (the behavior task). RESULTS: The MAC-awake value for the combination of isoflurane and nitrous oxide was 118 +/- 4% of the expected value (i.e., the two anesthetics were antagonistic for this effect). Consistent with antagonism, the anesthetic concentration predicted to suppress learning by 50% permitted significantly more learning, and the ED50 was 105 +/- 2% of that predicted. Neither the category task nor the behavior task demonstrated evidence of learning at 1.4 times MAC-awake. CONCLUSIONS: Our results are consistent with an antagonism between nitrous oxide and isoflurane; however, the degree of antagonism is small.

Adult↗
PubMed2004

Procedural learning in schizophrenia can reflect the pharmacologic properties of the antipsychotic treatments.

BACKGROUND: Conventional and atypical antipsychotics have different affinities for D2 receptors, and these receptors are principally located in the striatum. Given that this cerebral structure was previously found to play a major role in procedural learning, the antipsychotic treatment in schizophrenia may be determinant for the procedural learning profile of these patients. OBJECTIVE: The current study was aimed at verifying whether procedural learning differs in patients with schizophrenia treated with conventional antipsychotics and patients treated with atypical antipsychotics. METHOD: Forty-five patients with schizophrenia were divided into 3 different groups according to their pharmacologic treatment: (1) haloperidol, a classical neuroleptic with high D2 receptor affinity; (2) clozapine, an atypical neuroleptic with practically no D2 receptor affinity; and (3) risperidone, an atypical neuroleptic that nevertheless shows high D2 receptor affinity. Patients were compared to 35 control subjects on a visuomotor procedural learning task (mirror drawing). RESULTS: All patients were able to learn the task. However, those treated with haloperidol showed some degree of learning impairment, while those treated with clozapine or risperidone did not show this impairment. In addition, performance per se, regardless of the learning, was found to be affected in the haloperidol and risperidone, but not in the clozapine groups. CONCLUSION: Procedural learning in schizophrenia may be differentially affected, depending on the pharmacologic profiles of the antipsychotics used for the treatment of this illness.

Adult↗
PubMed2001

Sleep, memory, and learning.

The relationship of sleep to memory and learning is complex. Sleep affects memory, and memory must be present for learning to occur. A number of studies have been conducted to increase our understanding of their relationship. In addition to the numerous scientific investigations of each concept separately, sleep, memory, and learning have been studied together to determine (a) the effect of sleep on memory and learning, (b) the effect of sleep deprivation in general on memory and learning, (c) the effect of rapid eye movement (REM) sleep deprivation on memory and learning, (d) the effect of memory and learning on REM sleep, and (e) the effect of non-REM sleep loss on memory and learning. Neuroanatomic correlates have been pursued as well with most attention to the hippocampus. Despite considerable efforts to date, many of the studies reveal contradictory or inconclusive findings. Much remains unknown, and additional work is needed. Implications for nursing include those that have a direct effect on the patient, the nurse, and nursing science.

Health Promotion↗
PubMedDate not supplied

Preserved fronto-striatal plasticity and enhanced procedural learning in a transgenic mouse model of Alzheimer's disease overexpressing mutant hAPPswe.

Mutations in the amyloid precursor protein (APP) gene inducing abnormal processing and deposition of beta-amyloid protein in the brain have been implicated in the pathogenesis of Alzheimer's disease (AD). Although Tg2576 mice with the Swedish mutation (hAPPswe) exhibit age-related Abeta-plaque formation in brain regions like the hippocampus, the amygdala, and the cortex, these mice show a rather specific deficit in hippocampal-dependent learning and memory tasks. In view of recent findings showing that neural systems subserving different forms of learning are not simply independent but that depressing or enhancing one system affects learning in another system, we decided to investigate fronto-striatal synaptic plasticity and related procedural learning in these mutants. Fronto-striatal long-term depression (LTD) induced by tetanic stimulation of the cortico-striatal input was similar in Tg2576 and wild-type control mice. Behavioral data, however, pointed to an enhancement of procedural learning in the mutants that showed robust motor-based learning in the cross maze and higher active avoidance scores. Thus, in this mouse model of AD, an intact striatal function associated with an impaired hippocampal function seems to provide neural conditions favorable to procedural learning. Our results suggest that focusing on preserved or enhanced forms of learning in AD patients might be of interest to describe the functional reorganization of the brain when one memory system is selectively compromised by neurological disease.

Alzheimer Disease↗
PubMed2005

How can medical students learn in a self-directed way in the clinical environment? Design-based research.

AIM: This study aimed to establish whether and under what conditions medical students can learn in a self-directed manner in the clinical environment. METHOD: A web-based learning management system brought 66 placement students, in a problem-based learning (PBL) medical curriculum, into closer touch with their clinical learning objectives and ways of achieving them. Free response comments from 16 of them during the 7 weeks they used it, transcripts of group discussions before and after the period of use, and responses from all 66 students to a questionnaire were analysed qualitatively. RESULTS: Students were rarely fully autonomous or subservient. They valued affective and pedagogic support, and relied on teachers to manage their learning environment. With support, they were motivated and able to choose how and when to meet their learning needs. The new system was a useful adjunct. CONCLUSIONS: Self-direction, interpreted literally, was a method of learning that students defaulted to when support and guidance were lacking. They found "supported participation" more valuable. Learning in the clinical environment was a social process with as many differences from, as similarities to, PBL.

Computer-Assisted Instruction↗
PubMed1993

The structure of sleep is related to the learning ability of rats.

Using electroencephalographic methods, rats learning or not learning a two-way active avoidance task were found to differ significantly in the structure of sleep determined the day before training. The main differences concerned (i) synchronized sleep episodes followed by wakefulness, which were longer and fewer in learning rats; (ii) paradoxical sleep episodes, which were longer in learning rats. Significant correlations were present between the number and/or the average duration of synchronized sleep episodes followed by wakefulness or by paradoxical sleep and the number of avoidances or escapes scored in the training session. Power spectral analysis indicated that the relative output in the 6-7-Hz region was higher in learning rats, notably during short episodes of synchronized sleep followed by paradoxical sleep. As two-way active avoidance training induces comparable modifications in postacquisition sleep (Ambrosini et al., Physiol. Behav., 51, 217-226, 1992), the features of preacquisition sleep which prevail in learning rats might directly determine their capacity to learn. Alternatively, they might reflect the existence of a genetic determinant independently conditioning the ability to learn.

Animals↗
PubMed1995

The effects of AMPA-induced lesions of the septo-hippocampal cholinergic projection on aversive conditioning to explicit and contextual cues and spatial learning in the water maze.

The environmental context of an animal both subsumes and is associated with the explicit cues that guide its behavioural responses. Recent work in this laboratory suggests that learning about the relationship between the cues which comprise a context depends on the hippocampus. In the present study the role of the cholinergic input to the hippocampus in contextual learning was assessed in rats using a conditioned stimulus/context conditioning paradigm and spatial learning in the Morris water maze. In the former, a place preference apparatus provided the context. The subject was confined in the black chamber and a 'clicker' conditioned stimulus was presented five times in a 20 min period. A trace interval of 5 or 30 s, depending on the group, was interposed between the end of the clicker and a footshock. Theory predicts that animals in the 5 s condition will learn more about the clicker as a predictor of shock and become strongly conditioned, while those in the 30 s condition learn relatively more about the context. Conditioning to the clicker (conditioned stimulus) was measured in a separate lick suppression chamber--presentation of the clicker suppresses drinking, and contextual learning was determined by recording the time spent on the black side of the place preference apparatus when both the black and a familiar white chamber were accessible. Lesions of the medial septum/diagonal band induced by RS-alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) enhanced contextual learning in this paradigm but disrupted conditioned stimulus conditioning in the 30 s condition. Acquisition of the Morris water maze was largely unimpaired. The results are suggested to reflect a shift towards the use of hippocampal-dependent contextual learning strategies in lesioned animals.

Acetylcholine↗
PubMed2005

Olfactory learning-induced morphological modifications in single dendritic spines of young rats.

Learning-related morphological modifications in single dendritic spines were studied quantitatively in the brains of young Sprague-Dawley rats. We have previously shown that olfactory discrimination rule-learning results in transient physiological and morphological modifications in piriform cortex pyramidal neurons. In particular, spine density along the apical dendrites of neurons from trained rats is increased after learning. The aim of the present study was to identify and describe olfactory learning-induced modifications in the morphology of single spines along apical dendrites of the same type of neurons. By using laser-scanning confocal microscopy, we show that 3 days after training completion spines on neurons from olfactory discrimination trained rats are shorter as compared to spines on neurons from control rats. Further analysis revealed that spine shortening attributed to olfactory discrimination learning derives from shortening of spine head and not from shortening of spine neck. In addition, detailed analysis of spine head volume suggests that spines with large heads are absent after learning. As spine head size may be related to the efficacy of the synapse it bears, we suggest that modifications in spine head dimensions following olfactory rule-learning enhance the cortical network ability to enter into a 'learning mode', in which memories of new odours can be acquired rapidly and efficiently.

Analysis of Variance↗
PubMed2007

Spatial learning induces predominant downregulation of cytosolic proteins in the rat hippocampus.

Spatial learning is known to depend on protein synthesis in the hippocampus. Whereas the role of the hippocampus in spatial memory is established, the biochemical and molecular mechanisms underlying this process are poorly understood. To comprehend the complex pattern of protein expression induced by spatial learning, we analyzed alterations in the rat hippocampus proteome after 7 days of spatial learning in the Morris water maze. Forty Wistar rats were randomized into two groups. Animals of group A learned to localize a hidden platform in the water maze. Animals of group B served as controls and spent exactly the same time in the water maze as animals of group A. However, no platform was used in this test and the rats could not learn to localize the target. After the last trial, hydrophilic proteins from the hippocampus were isolated. A proteome-wide study was performed, based on two-dimensional gel electrophoresis and mass spectrometry. Compared with non-learning animals, 53 (70%) proteins were downregulated and 23 (30%) proteins were upregulated after 7 days in rats with spatial learning. The overall changes in protein expression, as quantified by the induction factor, ranged from -1.62 (downregulation to 62%) to 2.10 (upregulation by 110%) compared with controls (100%). Most identified proteins exhibit known functions in vesicle transport, cytoskeletal architecture, and metabolism as well as neurogenesis. These findings indicate that learning in the Morris water maze has a morphological correlate on the proteome level in the hippocampus.

Animals↗
PubMedDate not supplied

The social construction of learning disabilities.

Underpinning the technical gaze that dominates learning disabilities theory and practice is the assumption that learning disabilities are a pathology that resides in the heads of individual students, with the corollary that remedial efforts also focus on what goes on in the heads of students classified as learning disabled. This article begins with a critique of the ideology of individualism that situates individual success and failure in the heads of individuals as a means of introducing an alternative perspective--social constructivism--that locates learning and learning problems in the context of human relations and activity. Extended examples are used to illustrate how the performative aspects of learning disabilities emerge in the context of human relationships. The primary argument developed here is that one cannot be learning disabled on one's own. It takes a complex system of interactions performed in just the right way, at the right time, on the stage we call school to make a learning disability. The article concludes with a brief consideration of the instructional implications of a social constructivist stance.

Anthropology, Cultural↗