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PubMed1987

Selective memory impairment by phencyclidine in rats.

Phencyclidine (PCP) users sometimes report lack of recall of events occurring while they are under the influence of the drug. The present experiment was designed to test whether rats remember information learned after PCP administration. Rats were trained to choose one arm of a T-maze to obtain a food reward. The following day they were injected with either PCP (1 mg/kg) or vehicle and trained to choose the opposite arm for a reward (reversal learning). A third group of rats received neither injections nor training on the second day. On the third day, all rats were tested for their preference of maze arms. Rats who had been injected with saline before reversal learning chose the arm rewarded during the reversal, while rats receiving PCP on the second day chose randomly. The rats which did not learn the reversal chose the arm learned on day 1. These results indicate that while PCP did not interfere with the rats ability to learn, it interfered with long-term storage of information.

Animals↗
PubMed1995

NGF deprivation of adult rat brain results in cholinergic hypofunction and selective impairments in spatial learning.

Cholinergic hypofunction has often been correlated with a variety of behavioural impairments. In the present study, adult Wistar rats were intraventricularly infused with antibodies to nerve growth factor (anti-NGF) to examine the effects on cholinergic neurons of the basal forebrain, and on behavioural performance. Immunocytochemical techniques indicated that chronically infused anti-NGF penetrates into the basal forebrain, cortex, striatum, corpus callosum and hippocampus, confirming previous findings after a single injection. Treatment with anti-NGF for 1 or 2 weeks resulted in a significant decrease of 27-33% in density of choline acetyltransferase immunostaining of the cholinergic cell bodies in the medial septum and vertical diagonal band, and a 26% reduction in choline acetyltransferase enzyme activity in the septal area. An array of spatial learning Morris water maze tasks was used to distinguish between acquisition skills and the flexible use of learned information in novel tests. Rats subjected to the spatial learning paradigm received anti-NGF infusion for 2 weeks prior to and for another 2 weeks during the behavioural testing. The anti-NGF-treated animals were found to be no different from those receiving control serum in the Morris water maze acquisition task, either in the latency to find the platform or in the time spent searching in the training quadrant when the platform was removed. However, in consecutive extinction trials, anti-NGF rats continued to search in the empty training quadrant, suggesting the occurrence of perseveration; control rats expanded their search over other areas of the pool.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2005

Memory and selective learning in children with spina bifida-myelomeningocele and shunted hydrocephalus: a preliminary study.

BACKGROUND: Selective learning is the ability to select items of relevance from among less important items. Limited evidence exists regarding the efficiency with which children with spina bifida-myelomeningocele and shunted hydrocephalus (SB/SH) are able to learn information. This report describes initial data related to components of learning and metacognitive skills in children with SB/SH. METHODS: Twenty six children with SB/SH and 26 controls (age: 7-16 y) with average intelligence, and monolingual English-speaking backgrounds participated in the study. Exclusion criteria for the SB/SH group were: prior history of shunt infection, history of seizure or shunt malfunction within the previous three months, prior diagnoses of attention disorders and/or clinical depression. Children were presented lists of words with equal exemplars each of two distinct semantic categories (e.g. fruits, animals), and told to make as high a score as possible by learning the words. The value of the words was designated by category membership (e.g. animals = low value; fruits = high value). The total number of words learned across three learning trials was used to determine memory span. Selective learning efficiency (SLE) was computed as the efficiency with which items of greater value were selectively learned across three trials. RESULTS: Children with SB/SH did worse than controls on memory span (P < 0.05). Although SLE was not significantly different between groups, when asked what strategy was used in the selective learning tasks, 65% of the SB/SH children said they tried to remember all words (inefficient strategy). In contrast, 85% of controls said they tried to remember the higher value words--the more efficient strategy. CONCLUSION: Success in school is often dependent on the ability to recall important facts selectively and ignore less important information. Children with SB/SH in our study had a poor memory span and were unable to monitor and report an efficient and workable metacognitive strategy required to remember a list of words. Preliminary findings may begin to explain our previous clinical and research findings wherein children with SB/SH often focus on extraneous details, but demonstrate difficulty remembering the main gist of a story/event.

Journal Article↗
PubMedDate not supplied

A neural systems analysis of adaptive navigation.

In the field of the neurobiology of learning, significant emphasis has been placed on understanding neural plasticity within a single structure (or synapse type) as it relates to a particular type of learning mediated by a particular brain area. To appreciate fully the breadth of the plasticity responsible for complex learning phenomena, it is imperative that we also examine the neural mechanisms of the behavioral instantiation of learned information, how motivational systems interact, and how past memories affect the learning process. To address this issue, we describe a model of complex learning (rodent adaptive navigation) that could be used to study dynamically interactive neural systems. Adaptive navigation depends on the efficient integration of external and internal sensory information with motivational systems to arrive at the most effective cognitive and/or behavioral strategies. We present evidence consistent with the view that during navigation: 1) the limbic thalamus and limbic cortex is primarily responsible for the integration of current and expected sensory information, 2) the hippocampal-septal-hypothalamic system provides a mechanism whereby motivational perspectives bias sensory processing, and 3) the amygdala-prefrontal-striatal circuit allows animals to evaluate the expected reinforcement consequences of context-dependent behavioral responses. Although much remains to be determined regarding the nature of the interactions among neural systems, new insights have emerged regarding the mechanisms that underlie flexible and adaptive behavioral responses.

Animals↗
PubMed2003

Assessment of memory skills in illiterates: strategy differences or test artifact?

Previous studies have reported that illiterates perform more poorly than literates on a variety of neuropsychological measures. We investigated the hypothesis that putative memory deficits in illiterates are an artifact of the assessment tools used rather than a reflection of an 'underdeveloped' ability. In order to accomplish this, we designed two tests, a word list learning test and an object learning test. The illiterate group performed more poorly than semiliterate and literate groups on most variables of the word list learning test, but only on delayed recall and semantic clustering on the object learning test. Our findings suggest that poor memory performance among illiterates can be attributed both to the nature of the task, as well as to the use of different cognitive mechanisms to recall learned information. Presumably, formal education may enhance the innate ability of learning through training individuals in efficient learning and retrieval strategies. We emphasize the importance of developing and using ecologically valid neuropsychological tests to assess illiterate individuals.

Aged↗
PubMed1999

Bioethics committees--a health communication approach.

The modern health care system is being transformed as a consequence of scarce resources and better informed consumers. In this transformed health care system human communication has become a crucially important process. This essay examines the health communication functions performed by bioethics committees in health care delivery and makes recommendations for promoting the effective use of these groups within the modern health care system. The essay describes how bioethics committee can help establish a climate in which physicians and other committee members can share relevant health information, learn about patient and family concerns, promote health education and informed consent, and facilitate effective decision making about complex health care practice issues. It is argued that clear recognition and attention to the central role of effective communication within the bioethics committee is essential for the survival of the modern health care system since ethics committees depend on sharing relevant information to diagnose health problems, provide health care, promote health education, help in the formulation of new health care policies, and provide much-needed decision-making support to health care providers and consumers. The role that health communication expertise can perform in the effective operation and utilization of bioethics committees is described. We conclude that in order to provide needed support in addressing the many complexities of modern health care, bioethics committees must develop clear communication processes, norms, and roles.

Bioethics↗
PubMedDate not supplied

Cytochemical parameters of synaptic neurons in rats with different abilities to learn a food-procuring habit.

The characteristics of protein metabolism associated with cognitive activity were studied in neurons of layers III and IV of the sensorimotor cortex of rats, using two groups of Wistar rats. Regardless of the success of learning, information loading was most clearly reflected in the associative neurons of layer III. In rats with poor learning ability, these neurons showed increases in nuclear and cytoplasmic size, along with increases in protein concentration and content. The clearest changes in efferent neurons (layer V) were increases in the area and protein content, occurring only in the cytoplasm. In rats with good learning outcomes, all cytochemical parameters responded to information loading with decreases in layer III and increases in layer V protein contents and concentrations, affecting both the cytoplasm and nucleus. The question of whether the vector of changes in neuronal protein metabolism in response to information loading can be regarded as a measure of the individual features of higher nervous activity is discussed, as is the question of whether the magnitude of these changes is a measure of the complexity of a cognitive task.

Animals↗
PubMed1990

When cognitive exertion does not yield cognitive gain: toward an informational explanation of learned helplessness.

This study tested a new information-processing explanation of learned helplessness that proposes that an uncontrollable situation produces helplessness symptoms because it is a source of inconsistent, self-contradictory task information during problem-solving attempts. The flow of such information makes hypothesis-testing activity futile. Prolonged and inefficient activity of this kind leads in turn to the emergence of a state of cognitive exhaustion, with accompanying performance deficits. In 3 experiments, Ss underwent informational helplessness training (IHT): They were sequentially exposed to inconsistent task information during discrimination problems. As predicted, IHT was associated with subjective symptoms of irreducible uncertainty and resulted in (a) performance deterioration on subsequent avoidance learning, (b) heightened negative mood, and (c) subjective symptoms of cognitive exhaustion.

Achievement↗
PubMed1999

Conditions under which lorazepam can facilitate retrieval.

Memory is composed of three stages: acquisition, consolidation, and retrieval. By impairing acquisition processes, benzodiazepines cause anterograde amnesia while leaving intact information learned before the drug was taken. In some circumstances, retrieval of this information is even improved by benzodiazepines. It has been hypothesized that this phenomenon is not a true facilitation of retrieval processes, but is the result of reduced interference from items presented after drug administration and is thus a secondary consequence of drug-induced amnesia. Experiment 1 investigated the effect of 0.5, 1, and 2.5 mg of lorazepam on explicit episodic memory in healthy young volunteers. The 1-mg dose was found to significantly improve recall of items presented before drug administration without causing amnesia for items presented after drug administration, thus excluding an interference explanation. Experiment 2 investigated the conditions necessary to obtain facilitated retrieval with 1 mg of lorazepam. The results showed that facilitation was found only when two lists of semantically related material were presented, but that both of the lists could be presented before drug administration, thus excluding an effect of lorazepam on consolidation. Facilitation could be demonstrated in both direct (free recall) and indirect (backwards reading) retrieval tasks and when all of the material was presented after lorazepam administration. This improved retrieval could therefore be of clinical relevance, but any benefits would be reduced at higher doses that at the same time impair acquisition of new information. However, because 1 mg of lorazepam is an effective anxiolytic dose, these results suggest that it is possible to combine effective anxiety reduction with some benefits to memory.

Adolescent↗
PubMed1978

Science centers: a potential for learning.

The past decade has witnessed a proliferation of science-technology centers, or public places for informal learning about science and technology. Science centers are the only institutions that can provide the general public with participatory exhibits and experiences, together with an accurate scientific interpretation of the materials that are involved. The dramatic rise in attendance and the enthusiasm of repeat visitors to science centers reflect a strong public demand for exhibits designed to help the visitor develop a better understanding of the contemporary scientific issues of society.

Education, Continuing↗
PubMed1993

Phencyclidine disrupts acquisition and retention performance within a spatial continuous recognition memory task.

Rats with 1 or 2 mg/kg phencyclidine (PCP), 4 mg/kg PCP, or saline injections were tested for acquisition or retention performance of a spatial continuous recognition memory task. Results indicate that relative to controls and rats with injections of 1 and 2 mg/kg PCP rats with 4-mg/kg PCP injections were profoundly impaired in acquisition and somewhat impaired in retention of the task across all lags as measured by increases in latency for repeated items. Phencyclidine, through it presumed blocking action of the NMDA receptor, alters the consolidation of new spatial location information but does not have a major affect on short-term maintenance of previously learned information.

Analysis of Variance↗
PubMed2006

The clinical trial research participant as an inside trader: a legal and policy analysis.

This Article examines whether a participant in a clinical research trial for a drug obtains material nonpublic information about the drug and its manufacturer or licensor and, if so, whether the participant may lawfully trade securities based on that information. This issue has been noted but not examined in depth in several articles in recent years. After an introduction to the federal law of insider trading and a discussion of relevant aspects of a supervised research trial, the Article concludes that, absent an agreement to the contrary, the participant would be free to trade securities based on any material nonpublic information learned in the trial. The author evaluates the extent to which the information is material and nonpublic and then presents the policy issues surrounding whetherthe participantshould be precluded from trading when in possession of material nonpublic information gained as a result of participation in the trial. While not resolving the competing policy considerations, including the value of allowing participants to make disclosure of their experiences in the trial before publication of the results in a peer reviewed journal, the Article presents an approach for preventing the misuse of material nonpublic information gained in the clinical trial context, by obtaining an agreement from the participant, and an agreement from the limited circle of persons to whom the participant should be allowed to make disclosure in any event (such as his personal physician and family members), that would render any trading by them unlawful under the federal law of insider trading.

Clinical Trials as Topic↗
PubMed1998

Qualitative study of educational interaction between general practitioners and specialists.

OBJECTIVES: To identify the main barriers to effective educational interaction between general practitioners and specialists and to suggest ways of overcoming these barriers. DESIGN: Qualitative study using semistructured interviews and focus groups. A content analysis of the data was performed. SETTING: South and West Regional Health Authority. SUBJECTS: 12 general practitioner principals and 12 hospital consultants were sampled purposefully and underwent a semistructured interview; a further 16 general practitioners and 16 hospital consultants similarly sampled made up four focus groups representing the two branches of the medical profession. RESULTS: There was a mismatch between what the general practitioners wanted from specialists in educational terms, and what the specialists were providing. General practitioners wanted to learn information that was directly applicable to their clinical work and to use referrals as two way learning opportunities. They were not sufficiently explicit about their learning needs. Specialists preferred to concentrate on new developments in their subject and would benefit from learning different ways of teaching. The participants were willing to learn from each other. Three models of educational interaction were identified: traditional didactic lectures given by specialists to general practitioners, interactive clinically based teaching, and informal interaction based on referrals. CONCLUSIONS: The two main branches of the medical profession have to address several significant problems before the full potential of teaching and learning together can be realised.

Attitude of Health Personnel↗
PubMed1998

Local online learning of coherent information.

One of the goals of perception is to learn to respond to coherence across space, time and modality. Here we present an abstract framework for the local online unsupervised learning of this coherent information using multi-stream neural networks. The processing units distinguish between feedforward inputs projected from the environment and the lateral, contextual inputs projected from the processing units of other streams. The contextual inputs are used to guide learning towards coherent cross-stream structure. The goal of all the learning algorithms described is to maximize the predictability between each unit output and its context. Many local cost functions may be applied: e.g. mutual information, relative entropy, squared error and covariance. Theoretical and simulation results indicate that, of these, the covariance rule (1) is the only rule that specifically links and learns only those streams with coherent information, (2) can be robustly approximated by a Hebbian rule, (3) is stable with input noise, no pairwise input correlations, and in the discovery of locally less informative components that are coherent globally. In accordance with the parallel nature of the biological substrate, we also show that all the rules scale up with the number of streams.

Journal Article↗
PubMed2001

American Medical Association and American Osteopathic Association credit systems: accomplishing dual credit for a conference.

The need for collaboration in medical education is increasingly evident as allopathic and osteopathic physician communities continue to train physicians cooperatively. Therefore, ventures that hold dual accreditation in continuing medical education (CME) have increasing appeal to both physician groups. The Berkshire Medical Conference, a nationally accredited CME activity held annually in western Massachusetts and cosponsored by the University of Massachusetts Medical School, Berkshire Medical Center, and Berkshire Area Health Education Center, offered dual accreditation to allopathic and osteopathic physicians for the first time in its 16-year history. This dually accredited conference is the first such collaborative venture in the region. The specific criteria for accreditation for both physician groups were fulfilled, and the content also proved to be equally relevant. Evaluations indicated that learning objectives were met and the collaboration was successful in terms of the information learned by and about each group of physicians. As collaborative CME activities develop in the medical community, it is hoped that the lessons learned from the 16th Annual Berkshire Medical Conference, "Collaborations in Medicine," will serve as a model for future conferences and cooperative ventures between allopathic and osteopathic physicians.

Accreditation↗
PubMed2001

The topography of tactile learning in humans.

The spatial distribution of learned information within a sensory system can shed light on the brain mechanisms of sensory-perceptual learning. It has been argued that tactile memories are stored within a somatotopic framework in monkeys and rats but within a widely distributed network in humans. We have performed experiments to reexamine the spread of tactile learning across the fingertips. In all experiments, subjects were trained to use one fingertip to discriminate between two stimuli. Experiment 1 required identification of vibration frequency, experiment 2 punctate pressure, and experiment 3 surface roughness. After learning to identify the stimuli reliably, subjects were tested with the trained fingertip, its first and second neighbors on the same hand, and the three corresponding fingertips on the opposite hand. As expected, for all stimulus types, subjects showed retention of learning with the trained fingertip. However, the transfer beyond the trained fingertip varied according to the stimulus type. For vibration, learning did not transfer to other fingertips. For both pressure and roughness stimuli, there was limited transfer, dictated by topographic distance; subjects performed well with the first neighbor of the trained finger and with the finger symmetrically opposite the trained one. These results indicate that tactile learning is organized within a somatotopic framework, reconciling the findings in humans with those in other species. The differential distribution of tactile memory according to stimulus type suggests that the information is stored in stimulus-specific somatosensory cortical fields, each characterized by a unique receptive field organization, feature selectivity, and callosal connectivity.

Adult↗
PubMed2003

Delayed feedback effects on rule-based and information-integration category learning.

The effect of immediate versus delayed feedback on rule-based and information-integration category learning was investigated. Accuracy rates were examined to isolate global performance deficits, and model-based analyses were performed to identify the types of response strategies used by observers. Feedback delay had no effect on the accuracy of responding or on the distribution of best fitting models in the rule-based category-learning task. However, delayed feedback led to less accurate responding in the information-integration category-learning task. Model-based analyses indicated that the decline in accuracy with delayed feedback was due to an increase in the use of rule-based strategies to solve the information-integration task. These results provide support for a multiple-systems approach to category learning and argue against the validity of single-system approaches.

Discrimination Learning↗