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PubMed2002

mGluR1 in cerebellar Purkinje cells is required for normal association of temporally contiguous stimuli in classical conditioning.

In metabotropic glutamate receptor-subtype 1 (mGluR1)-null (mGluR1-/-) mice, cerebellar long-term depression (LTD) and several forms of memory are impaired. However, because mGluR1 is expressed in various brain regions in wild-type mice, it has been difficult to identify which type of memory depends on mGluR1 expressed in a given brain region. Furthermore, severe ataxia in mGluR1-/- mice complicated interpretation of the data from non-cerebellum-dependent tasks. We have generated mGluR1-rescue mice, which express mGluR1 only in Purkinje cells (PCs) of their cerebellum, by introducing the mGluR1alpha transgene into mGluR1-/- mice under the control of a PC-specific promoter. The mGluR1-rescue mouse has normal LTD and displays no apparent ataxia. Therefore, this mouse is the first animal model in which effects of mGluR1 deficiency outside PCs can be studied without cerebellar dysfunction. We used three eyeblink conditioning paradigms with different temporal specificities between conditioned stimulus (CS) and unconditioned stimulus (US). Delay conditioning, in which CS and US coterminate, was impaired in mGluR1-/- mice but normal in mGluR1-rescue mice. However, both strains of mice displayed severe impairment in trace conditionings, in which a stimulus-free interval of 250 or 500 ms intervened between CS and US. We also examined social transmission of food-preference and novel-object-recognition memory tests. In these tasks, mGluR1-rescue mice showed normal short-term but impaired long-term memory. We conclude that mGluR1 in PCs is indispensable for normal learning of association of temporally contiguous stimuli in associative conditioning. In contrast, mGluR1 in other cell types is required for associating discontiguous stimuli and long-term memory formation in nonspatial hippocampus-dependent learning.

Animals↗

PubMed2000

[The problem-based medical curriculum in Trondheim--did it turn out as planned?].

BACKGROUND: A problem-based (PBL) medical curriculum was implemented in 1993 at the Medical School of the Norwegian University of Science and Technology. The objective of this study was to examine how the planned reduction in scheduled activities, the emphasis on student-centred learning, and the integration of disciplines have been implemented. MATERIAL AND METHODS: The schedules in the old and new programmes were the main sources of data. Each scheduled activity was coded according to discipline taught and chosen learning method. RESULTS: The number of hours spent on scheduled activities was much higher in the new programme (n = 4,009) than in the intended (n = 2,974), and it was even slightly higher than in the old programme (n = 3,785). In contrast to plans there was less student-centered learning, and basic science was mainly taught during the two first years. INTERPRETATION: Contrary to plans, the new curriculum in Trondheim has not become a pure PBL curriculum. It is a hybrid model involving a number of learning methods. A high degree of autonomy of the individual faculty members in the planning, and resistance to change among faculty members may have caused less radical changes. This is not necessarily negative; the new model may be a pragmatic synthesis between new and traditional medical education.

Curriculum↗

PubMed1988

Hypochondriacal traits in medical inpatients.

Hypochondriacal traits were examined in 100 general medical inpatients, and correlates of these traits were examined from four perspectives: (1) emotional distress; (2) affective inhibition; (3) learned social behavior; and (4) symptom misinterpretation. In contrast to previous studies of hypochondriasis in general medical populations, this study examined patients' illness perceptions and presentation in relationship to objective health status as assessed by their treating physicians. Data concerning the illness being treated and associated illness behavior were obtained from patients and their treating physicians. Results suggested that hypochondriacal traits of "disease phobia," disease conviction, bodily preoccupation, perceptions that one's illness is more severe than the physician's assessment, and illness presentation disproportionate to demonstrable organic disease were quite prevalent. On multiple regression analyses, correlates pertaining to emotional distress appear to be preeminent in the prediction of hypochondriacal traits. However, variables pertaining to learned social behavior also provided further understanding of hypochondriacal traits in medical inpatients beyond that explained by emotional distress.

Adult↗

PubMed1998

Effects of coaching on detection of malingering on the California Verbal Learning Test.

The diagnostic accuracy of California Verbal Learning Test (CVLT) indices to detect malingered head injury was examined using a simulation paradigm that included naive malingerers, malingerers provided with information about head injury, and normal controls (N = 90). The application of diagnostic cutoff scores for Recognition Discriminability and Recognition Hits derived from populations of individuals with bona fide head injury and individuals suspected of malingering (Millis et al., 1995) proved highly sensitive and modestly specific in detecting feigned head injury among both simulation groups. Results of analyses of variance and logistic regression support previous findings that malingerers overestimate memory impairment associated with mild head injury; however, they indicate that exposure to a simple instructional set may render insensitive many indices of malingering. In contrast, indices based on more subtle principles of learning theory hold promise in the detection of malingering, even in the presence of an instructional set.

Adolescent↗

PubMed1996

Rapid identification of Streptococcus and Enterococcus species using diffuse reflectance-absorbance Fourier transform infrared spectroscopy and artificial neural networks.

Diffuse reflectance-absorbance Fourier transform infrared spectroscopy (FT-IR) was used to analyse 19 hospital isolates which had been identified by conventional means to one Enterococcus faecalis, E. faecium, Streptococcus bovis, S. mitis, S. pneumoniae, or S. pyogenes. Principal components analysis of the FT-IR spectra showed that this 'unsupervised' learning method failed to form six separable clusters (one of each species) and thus could not be used to identify these bacteria base on their FT-IR spectra. By contrast, artificial neural networks (ANNs) could be trained by 'supervised' learning (using the back-propagation algorithm) with the principal components scores of derivatised spectra to recognise the strains from their FT-IR spectra. These results demonstrate that the combination of FT-IR and ANNs provides a rapid, novel and accurate bacterial identification technique.

Algorithms↗

PubMed1993

Varieties of learning and memory in animals.

It is often assumed that there is more than one kind of learning--or more than one memory system--each of which is specialized for a different function. Yet, the criteria by which the varieties of learning and memory should be distinguished are seldom clear. Learning and memory phenomena can differ from one another across species or situations (and thus be specialized) in a number of different ways. What is needed is a consistent theoretical approach to the whole range of learning phenomena, and one is explored here. Parallels and contrasts in the study of sensory systems illustrate one way to integrate the study of general mechanisms with an appreciation of species-specific adaptations.

Animals↗

PubMed2005

Learning-induced plasticity of cortical representations does not affect GAD65 mRNA expression and immunolabeling of cortical neuropil.

Two forms of glutamic acid decarboxylase (GAD) are present in inhibitory neurons of the mammalian brain, a 65-kDa isoform (GAD65) and a 67-kDa isoform (GAD67). We have previously found that GAD67 is upregulated during learning-dependent plasticity of cortical vibrissal representations of adult mice. After sensory conditioning involving pairing stimulation of vibrissae with a tail shock, the increase in mRNA expression and density of GAD67-immunoreactive neurons was observed in barrels representing vibrissae activated during the training. In the present study, using the same experimental model, we examined GAD65 mRNA and protein levels in the barrel cortex. For this purpose, we used in situ hybridization and immunohistochemistry. No changes in the level of GAD65 mRNA expression were detected after the training. The pattern of GAD65 mRNA expression was complementary to that observed for GAD67. Immunocytochemical analysis found no changes in immunolabeling of neuropil of the barrels representing the vibrissae activated during the training. The results show that, in contrast to GAD67, cortical plasticity induced by sensory learning does not affect the expression of GAD65.

Animals↗

PubMed2000

Bioscience in the pre-registration curriculum: finding the right teaching strategy.

With the transition of pre-registration nursing programmes into higher education, a disproportionate number of problems have arisen in relation to the bioscience component of the curriculum. Therefore, a survey was undertaken to obtain the views of students (n = 294) and staff (n = 57) to identify effective teaching strategies to facilitate students' learning and understanding of this difficult area of the curriculum. In contrast to the staff, the majority of students found all three teaching strategies (lectures, tutorials and laboratory sessions) of approximately equal value to their learning and practice. Our findings suggest that students' problems with the biosciences could be ameliorated by adjustments in curriculum apportionment. Our data would support the continuation of lead lectures and laboratory work in bioscience. However, a tutorial system, specifically designed to overcome the particular difficulties experienced by nursing students in this area, is needed. This should augment, not replace, lectures and teaching laboratories. There was little indication that such a redistribution of resources would be favoured by the majority of the staff.

Attitude of Health Personnel↗

PubMed2006

Organisational learning and self-adaptation in dynamic disaster environments.

This paper examines the problems associated with inter-organisational learning and adaptation in the dynamic environments that characterise disasters. The research uses both qualitative and quantitative methods to investigate whether organisational learning took place during and in the time in between five disaster response operations in Turkey. The availability of information and its exchange and distribution within and among organisational actors determine whether self-adaptation happens in the course of a disaster response operation. Organisational flexibility supported by an appropriate information infrastructure creates conditions conducive to essential interaction and permits the flow of information. The study found that no significant organisational learning occurred within Turkish disaster management following the earthquakes in Erzincan (1992), Dinar (1995) and Ceyhan (1998). By contrast, the 'symmetry-breaking' Marmara earthquake of 1999 initiated a 'double loop' learning process that led to change in the organisational, technical and cultural aspects of Turkish disaster management, as revealed by the Duzce earthquake response operations.

Acclimatization↗

PubMed1995

Excitatory amino acid receptors within nucleus accumbens subregions differentially mediate spatial learning in the rat.

The present experiments investigated the effects of excitatory amino acid antagonists, infused into core and shell subregions of the nucleus accumbens, on spatial behavior in the rat. A food-search task was used, in which animals learn a specific pattern of food gathering; duration of each trial (time taken to gather all four pellets) and number of errors (visits to empty holes) were measured. In experiment 1, animals first underwent training, and subsequently were given microinfusions of either D-2-amino-5 phosphonopentanoic acid (AP-5), an N-methyl-d-aspartate (NMDA) antagonist (0, 0.2, 1.0µg/0.5µl), or 6,7-dinitroquinoxaline-2,3-dione (DNQX), an antagonist of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) and kainate receptors (0, 0.075, 0.75µg/0.5µl). AP-5-significantly increased trial duration in both core and shell groups, but increased errors only in the core group. DNQX treatment also impaired performance in both groups, but the effect was greater in the core group compared with the shell group. In experiment 2, animals were treated during acquisition. Rats infused with AP-5 (1µg/0.5µl) took significantly longer to finish trials, made more errors and showed a marked learning impairment across days. AP-5 impaired learning in both core and shell groups, but the disruption was significantly greater in the core group. DNQX (0.75µg/0.5µl) also impaired learning when infused into the core during acquisition; however, the pattern of disruption contrasted markedly with that of AP-5. DNQX in the shell had no effect on trial duration during learning. It is hypothesized that both NMDA and non-NMDA receptors in the nucleus accumbens mediate spatial learning and performance, and that NMDA receptors may have a relatively more important role in memory or retrieval mechanisms. Moreover, the core subregion may be preferentially involved in the control of spatial behavior.

Journal Article↗

PubMed1999

Interactive contributions of intracellular calcium and protein phosphatases to massed-trials learning deficits in Hermissenda.

Using Hermissenda as subjects, massed-trials training deficits were examined. Associative pairings of light and rotation induced a progressively greater conditioned foot contraction in response to light as the intertrial interval (ITI) was extended (up to 8 min). In contrast, a short ITI (30 s) produced no evidence of learning. In a corresponding in vitro conditioning experiment that mimicked training of the intact animal, facilitation of neuronal excitability in the animal's B photoreceptors paralleled the results obtained in vivo. Imaging of intracellular Ca2+ using Fura-2 indicated that Ca2+ levels remained elevated during short ITIs. This Ca2+ accumulation appears to induce activation of protein phosphatases because normal facilitation of the B photoreceptors was induced with a short ITI if training occurred in the presence of a phosphatase inhibitor. These results suggest that intracellular Ca2+ and protein phosphatases contribute interactively to the kinetics of memory formation and provide evidence that an accumulation of intracellular Ca2+ across training trials may impede memory formation.

Animals↗

PubMed2001

Effects of dietary restraint on flavour-flavour learning.

Flavour preference learning in 21 restrained and 21 unrestrained females was explored using an evaluative conditioning paradigm. Each participant was exposed to an adapted version of the procedure used by Johnsrude et al., (1999, Learning & Motivation30, 250-264). During conditioning, participants sampled 10 instances each of three novel flavours presented in a semi-randomized order. After sampling a flavour they were instructed to eat a sweet according to three different flavour-reinforcement contingencies. One flavour was accompanied by a sweet on 90% of trials and was presented alone on 10% of the trials, while the remaining flavours were rewarded at ratios 50% : 50% and 10% : 90%, respectively. The conditioning phase occurred in conjunction with a counting task requiring continuous use of working memory, and was immediately followed by the participants making hedonic ratings of each flavour. Very few participants showed awareness of the purpose of the experiment or the specific reward contingencies. Despite this, the ratings given by the unrestrained eaters were highly correlated with the reward ratio experienced during conditioning. In contrast, restrained eaters exhibited no evidence for evaluative learning. These findings may explain the equivocal nature of results from previous studies of positive flavour-flavour learning (FFL) and may offer a novel theoretical context within which to study dietary restraint.

Adult↗

PubMed1981

Exploiting gravity in abdominal angiography.

The difference between the specific gravity of blood and contrast medium and the consequent tendency of contrast media to fill the lower tissues is exploited in abdominal angiography by special positioning of patients: prone for the coeliac, hepatic and mesenteric arteries, prone with the legs raised for abdominal aortography; lateral decubitus on the side of interest for renal angiography. The advantages are better parenchymal opacification, increased contrast and improved details. Gravity positioning saves time and material, and is easy to learn.

Angiography↗

PubMed2006

Gestational methylazoxymethanol acetate treatment impairs select cognitive functions: parallels to schizophrenia.

Gestational methylazoxymethanol acetate (MAM) exposure has been suggested to produce neural and behavioral abnormalities similar to those seen in schizophrenia. In order to assess MAM treatment as a model of schizophrenia, pregnant female rats were injected with MAM (22 mg/kg) on gestational day 17 and their offspring were assessed in adulthood on a series of cognitive tasks. The first experiment involved an attentional set-shifting task, a rodent analog of the Wisconsin card sort task. In experiment 2, animals were tested on the 5-choice serial reaction time task, a rodent analog of the continuous performance task. In the final experiment animals were assessed on a differential reinforcement of low rate of responding 20 s schedule of reinforcement (DRL-20), a task that is sensitive to changes in inhibitory control. In the first experiment, MAM-treated animals required a greater number of trials than controls to successfully learn an extradimensional shift on the set-shifting task, and had difficulties in learning to reverse a previously acquired discrimination. In contrast, MAM-treated animals showed little impairment on the 5-choice task, aside from a modest but consistent increase in premature responding. Finally, MAM exposed animals showed substantial impairments in DRL performance. Post-mortem analysis of brain tissue showed significant decreases in tissue weight in the hippocampus, parietal cortex, prefrontal cortex, and dorsal striatum of MAM-treated animals. These results support the notion that MAM treatment may simulate some aspects of schizophrenic cognition.

Animals↗

PubMed1995

Acute ethanol impairs spatial memory but not stimulus/response memory in the rat.

The present studies investigate how acutely administered ethanol (ETOH) affects the use of spatial memory. Previous electrophysiological results have shown that acutely administered ETOH alters the firing of hippocampal neurons and that prenatal or chronic exposure to ETOH produces deficits on spatial learning tasks, tasks dependent on the hippocampus. In contrast, it has also been demonstrated that acutely administered ETOH does not impair spatial localization. In the current studies, rats were trained to perform a spatial or stimulus/response task under saline. After training, rats were injected with ETOH, and the use of spatial or stimulus/response memory was tested. Acutely administered ETOH impaired the use of spatial memory, but not the use of stimulus/response memory. Because the use of spatial memory requires an intact hippocampus, the present studies suggest that acutely administered ETOH selectively impairs behaviors dependent on the hippocampus.

Animals↗

PubMed1987

Fengabine, a novel antidepressant GABAergic agent. I. Activity in models for antidepressant drugs and psychopharmacological profile.

Fengabine (SL 79.229) is a novel benzylidene derivative with clinically proven antidepressant action. Fengabine is active in behavioral models for antidepressant drug action, reversing the passive avoidance deficit in olfactory bulbectomized rats, antagonizing the escape deficit in the learned helplessness model and decreasing paradoxical sleep in the rat. In contrast to tricyclic antidepressants, fengabine antagonizes 5-hydroxytryptophan-induced head twitches and only weakly reverses reserpine-induced ptosis. Fengabine inhibits neither monoamine uptake nor monoamine oxidase. A GABAergic mechanism of fengabine is indicated as bicuculline reverses its action in the olfactory bulbectomy and learned helplessness models. The wide-spectrum anticonvulsant action of fengabine is consistent with a GABA-mimetic action and is in contrast to the proconvulsant effect of most classical antidepressants.

Animals↗

PubMed1995

Nonlinear gated experts for time series: discovering regimes and avoiding overfitting.

In the analysis and prediction of real-world systems, two of the key problems are nonstationarity (often in the form of switching between regimes) and overfitting (particularly serious for noisy processes). This article addresses these problems using gated experts, consisting of a (nonlinear) gating network, and several (also nonlinear) competing experts. Each expert learns to predict the conditional mean, and each expert adapts its width to match the noise level in its regime. The gating network learns to predict the probability of each expert, given the input. This article focuses on the case where the gating network bases its decision on information from the inputs. This can be contrasted to hidden Markov models where the decision is based on the previous state(s) (i.e. on the output of the gating network at the previous time step), as well as to averaging over several predictors. In contrast, gated experts soft-partition the input space, only learning to model their region. This article discusses the underlying statistical assumptions, derives the weight update rules, and compares the performance of gated experts to standard methods on three time series: (1) a computer-generated series, obtained by randomly switching between two nonlinear processes; (2) a time series from the Santa Fe Time Series Competition (the light intensity of a laser in chaotic state); and (3) the daily electricity demand of France, a real-world multivariate problem with structure on several time scales. The main results are: (1) the gating network correctly discovers the different regimes of the process; (2) the widths associated with each expert are important for the segmentation task (and they can be used to characterize the sub-processes); and (3) there is less overfitting compared to single networks (homogeneous multilayer perceptrons), since the experts learn to match their variances to the (local) noise levels. This can be viewed as matching the local complexity of the model to the local complexity of the data.

Computers↗

PubMed2003

The role of the prefrontal cortex in object-place learning: a test of the attribute specificity model.

In order to test an attribute specificity model of prefrontal cortex function, rats with lesions in the prelimbic-infralimbic (PL-IL) or anterior cingulate and precentral (AC-PC) subregions of the medial prefrontal cortex and controls were trained on an object-place paired associate task. Rats with AC-PC lesions acquired the task as readily as controls. In contrast, the PL-IL lesioned rats did not learn the task. Whenever higher order processing is required to solve a task, the data support an attribute-specificity model of prefrontal cortex function in that the PL-IL cortices support both object and place attribute information in a variety of tasks including object-place paired associate learning.

Animals↗