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Percutaneous endoscopic trigonoplasty: a minimally invasive approach to correct vesicoureteral reflux.

PURPOSE: A procedure was designed to correct vesicoureteral reflux with minimally invasive technology. MATERIALS AND METHODS: A total of 22 children 14 months to 18 years old underwent percutaneous endoscopic trigonoplasty between January and June 1995. Followup ranges from 4 to 11 months. In 32 ureters reflux was grade 2 in 13, grade 3 in 13, grade 4 in 5 and grade 5 in 1. RESULTS: All patients had normal sonography of the kidneys after surgery. On followup voiding cystourethrography at 2 or 6 months there was resolution of reflux in 20 of the 32 ureters (62.5%). The probability of resolution was unrelated to patient age, laterality of reflux, initial grade, operative sequence or preoperative bladder instability. The 3 major complications were vesicovaginal fistula, hyponatremia and perivesical fluid collection. CONCLUSIONS: Percutaneous endoscopic trigonoplasty is technically feasible but it involves a distinct learning curve. It offers significant advantages related to more rapid recovery with less discomfort. The success rate is modest at present. If it were to be improved with technical modifications, percutaneous endoscopic trigonoplasty may change the basic approach to treating children with vesicoureteral reflux.

Adolescent↗

Verb learning in children with SLI: frequency and spacing effects.

PURPOSE: This study explored the effect of frequency (number of presentations), and spacing (period between presentations) on verb learning in children with specific language impairment (SLI). Children learn words more efficiently when presentations are frequent and appropriately spaced, and this study investigated whether children with SLI likewise benefit. Given that these children demonstrate greater frequency dependence and rapid forgetting of recently acquired words, an investigation of frequency and spacing in this population is especially warranted. METHOD: Twenty-four children with SLI (mean age 5;6 [years;months]) and 24 language-matched control children (mean age 3;4) were taught novel verbs during play sessions. In a repeated measures design, 4 experimental conditions combined frequency (12 or 18 presentations) and spacing (all presentations in 1 session, or spread over 4 days). Comprehension and production probes were administered after the final session and 1 week later. RESULTS: Although the children with SLI benefited significantly from frequent and widely spaced presentations, there were no significant effect in the control group. The language-impaired children showed rapid forgetting. CONCLUSIONS: The frequency and spacing of presentations crucially affect the verb learning of children with SLI. A training regimen characterized by appropriately spaced intervals and moderate repetition will optimally benefit lexical learning.

Case-Control Studies↗

Properties and mechanisms of long-term synaptic plasticity in the mammalian brain: relationships to learning and memory.

Long-term potentiation (LTP) in the hippocampus and long-term depression (LTD) in the cerebellum are two forms of long-lasting synaptic plasticity that currently serve as our primary experimental models of learning and memory formation in mammals. In recent years, there have been considerable advances in our understanding of the cellular and molecular mechanisms of these and other forms of synaptic plasticity. This article presents an overview of these developments, considers the relationship of long-term synaptic plasticity mechanisms to learning and memory in view of these developments, and suggests future directions for research in this rapidly growing area of neuroscience.

Animals↗

Rapid communication: cleaning up a Hartley oscillator.

In a programme to understand, and learn to control, radiofrequency interference from neurological prostheses, it was discovered that a harmless-looking Hartley oscillator (one type of harmonic oscillator) generated a forest of harmonics extending to 1 GHz. These harmonics were not difficult to eliminate. The point of this paper is to emphasize that, given the selection of instruments used by most development engineers, the harmonics would probably have been missed.

Prostheses and Implants↗

Discrimination of compound stimuli involving the presence or absence of a distinctive visual feature.

Pigeons learned a free operant, go/no-go discrimination between stimuli produced by rapid alternation of different features on the response key. The 0 degrees -B compound consisted of a vertical black line on a white background (the 0 degrees feature) alternated with a blank white field (the B feature), with successive 0.75-sec feature on periods separated by 0.20-sec dark periods. Pecks at the alternating 0 degrees and B features were recorded separately. When pecks at the 0 degrees -B compound were reinforced and pecks at the B-B stimulus (repeated brief presentations of the B feature) were extinguished, the birds pecked more at the 0 degrees feature than at the B feature in the 0 degrees -B compound; subsequently, decremental line-tilt generalization gradients were obtained. When pecks at B-B were reinforced and pecks at 0 degrees -B were extinguished, the rate of pecking at the 0 degrees feature decreased to a low level much more rapidly than did the rate of pecking at the B feature in the 0 degrees -B compound; incremental line-tilt gradients were obtained. Following training with pecks at 0 degrees -B reinforced and pecks at 0 degrees -0 degrees extinguished, incremental line-tilt gradients were obtained, whereas the gradients were decremental following training with 0 degrees -0 degrees reinforced and 0 degrees -B extinguished.

Animals↗

Modification of environmentally cued tolerance to ethanol in mice.

Tolerance to the hypnotic and hypothermic effects of ethanol in mice develops with multiple injections. The tolerance to both of these effects of ethanol can be reduced by testing the animals in a novel environment, suggesting that the tolerance may be learned. Tolerance to the hypothermic effect of ethanol develops more rapidly than tolerance to the hypnotic effect. Disruption of the brain catecholamine systems, with either 6-hydroxydopamine or alpha-methyl-p-tyrosine slows the rate of development of tolerance to the hypnotic effect of ethanol. Intraventricular injection of the serotonergic neurotoxin 5,7-dihydroxytryptamine, increases initial sensitivity to ethanol-induced narcosis and facilitates the development of tolerance to the hypnotic effects of ethanol. Tolerance to the hypothermic effect of ethanol in a familiar environment is unaffected by either of the neurotoxins or by alpha-methyl-p-tyrosine. However, initial sensitivity to the temperature-lowering effect of ethanol is increased by 6-hydroxydopamine and decreased by alpha-methyl-p-tyrosine administration. Learning may be an important factor in development of tolerance to ethanol under some conditions and tolerance produced under these conditions can be modified by disruption of central catecholamine systems.

5,7-Dihydroxytryptamine↗

Advancing health policy in nursing education through service learning.

Knowledge of health policy is an increasingly important aspect of nursing practice and education, especially as nurses strive to improve the rapidly changing health care delivery system. At the same time, many educators, researchers, foundations, and government officials are touting the benefits of service learning. In particular, service learning offers ways to enhance partnerships between academia and community agencies and to extend learning beyond the traditional classroom. We present a model for educating nurses as advanced practice nurses in health policy that links service learning with a framework for the political development of nurses. Under the rubric of service learning, the curriculum is based on the overlap among health policy, the role of the nurse as consultant, and community-based care. After discussing the importance of health policy for graduate nursing education and reviewing the essentials of service learning, we describe a three-semester graduate sequence in health policy service learning. The focus is on the clinical and classroom components of both individual and group practica and their relationship to stages of nursing's political development. The article concludes with evaluation considerations and the implications of our work for nursing theory, research, practice, and education.

Connecticut↗

Experience-dependent changes in cerebral functional connectivity during human rapid eye movement sleep.

One function of sleep is hypothesized to be the reprocessing and consolidation of memory traces (Smith, 1995; Gais et al., 2000; McGaugh, 2000; Stickgold et al., 2000). At the cellular level, neuronal reactivations during post-training sleep in animals have been observed in hippocampal (Wilson and McNaughton, 1994) and cortical (Amzica et al., 1997) neuronal populations. At the systems level, using positron emission tomography, we have recently shown that some brain areas reactivated during rapid-eye-movement sleep in human subjects previously trained on an implicit learning task (a serial reaction time task) (Maquet et al., 2000). These cortical reactivations, located in the left premotor area and bilateral cuneus, were thought to reflect the reprocessing--possibly the consolidation--of memory traces during post-training rapid-eye-movement sleep. Here, the experience-dependent functional connectivity of these brain regions is examined. It is shown that the left premotor cortex is functionally more correlated with the left posterior parietal cortex and bilateral pre-supplementary motor area during rapid-eye-movement sleep of subjects previously trained to the reaction time task compared to rapid-eye-movement sleep of untrained subjects. The increase in functional connectivity during post-training rapid-eye-movement sleep suggests that the brain areas reactivated during post-training rapid-eye-movement sleep participate in the optimization of the network that subtends subject's visuo-motor response. The optimization of this visuo-motor network during sleep could explain the gain in performance observed during the following day.

Brain Mapping↗

Current state of knowledge about the mechanisms of alcohol tolerance.

Far from being a simple homeostatic response to the presence of ethanol in the brain, tolerance is now recognized as a complex process which can develop within various time frames (acute, rapid, chronic) and in which the drug interacts with various environmental and cognitive factors, including associative and operant learning. A major question is whether the acute form is an innate adaptive response, which is converted into the rapid and chronic forms by the action of these external influences. So far, all behavioral and neuropharmacological manipulations that alter chronic tolerance also modify rapid and acute tolerance in similar ways. These include lesions of serotonergic forebrain projections, blockade of NMDA-type glutamate receptors and calcium "L" channels, central or peripheral injection of vasopressin and blockade of vasopressin V1 receptors. Cytochemical and immunofluorescence studies, combined with use of retrograde tracers, indicate the existence of a septohippocampal circuit which may mediate the interactions of these diverse elements in the production and maintenance of tolerance. There is limited evidence that development of tolerance leads to increased consumption of ethanol in experimental animals, but the clinical significance of these findings remains to be proven.

Journal Article↗

Hippocampal synaptic transmission enhanced by low concentrations of nicotine.

Nicotine obtained from tobacco can improve learning and memory on various tasks and has been linked to arousal, attention, rapid information processing, working memory, and long-term memories that can cause craving years after someone has stopped smoking. One likely target for these effects is the hippocampus, a centre for learning and memory that has rich cholinergic innervation and dense nicotinic acetylcholine receptor (nAChR) expression. During Alzheimer's dementia there are fewer nAChRs and the cholinergic inputs to the hippocampus degenerate. However, there is no evidence for fast synaptic transmission mediated by nAChRs in the hippocampus, and their role is not understood. Nicotine is known to act on presynaptic nAChRs within the habenula of chick to enhance glutamatergic transmission; here we report that a similar mechanism operates in the hippocampus. Measurements of intracellular Ca2+ in single mossy-fibre presynaptic terminals indicate that nAChRs containing the alpha7 subunit can mediate a Ca2+ influx that is sufficient to induce vesicular neurotransmitter release. We propose that nicotine from tobacco influences cognition by enhancing synaptic transmission. Conversely, a decreased efficacy of transmission may account for the deficits associated with the loss of cholinergic innervation during Alzheimer's disease.

Action Potentials↗

Cognitive functions in prepsychotic patients.

OBJECTIVE: Cognitive dysfunctions are now widely understood as an essential feature of schizophrenia. A great number of cognitive disturbances have been described in drug-naive first-episode patients as well. The full-blown psychotic symptoms are usually preceded by a longer prodromal period, in which non-specific psychological disturbances are already present. The late prodromal phase is also coined as the prepsychotic state, with attenuated, isolated psychotic symptoms. The aim of the present study was to detect cognitive dysfunctions among young adults at the prepsychotic stage with the use of a standardized computer based cognitive test battery. METHOD: Eleven (9 men, 2 women) young Hungarian adults referred to the Outpatient Clinic of the Department of Psychiatry at the University of Debrecen were studied. The patients were re-evaluated for psychotic symptoms after 12 months. The patients had no history of psychiatric disorders or psychotic episodes and were referred by general practitioners on account of non-specific emotional or behavioural abnormalities. The subjects were asked to perform a series of 13 computerized neuropsychological tests of the Cambridge Neuropsychological Test. The performance of the patients were compared to that of the standardized database of the Cambridge Neuropsychological Test. RESULTS AND DISCUSSION: The performance of the prepsychotic patients was significantly lower compared to the healthy individuals in the paired associate learning (PAL, p<0.001), Spatial recognition memory (SRM, p<0.05), Rapid visual processing (RVP, p<0.05), and Spatial working memory (SWM, p<0.05) tests. CONCLUSION: Cognitive deficits were found mainly in attentional, frontal and prefrontal cognitive functions. These impairments may be present at the early stages of the development of psychosis and the standardized cognitive test battery (CANTAB) might be a useful tool for the detection of early cognitive impairments and provide a rationale for early intervention in individuals at risk of developing psychosis.

Adult↗

[Experimental techniques for developing new drugs acting on dementia (7)--A water-finding task for use with mice: utility for evaluating latent learning].

This article describes a water-finding (WF) task for use with mice in which the animals are not required to perform a special behavior and are not reinforced positively by water or feed during the training stage. The test apparatus consists of a rectangular open field with an alcove in the middle of one of the long walls of the enclosure. A metal drinking tube is inserted into the center of the alcove ceiling. Nonwater-deprived mice are placed individually into the test apparatus and are allowed to explore the environment freely during the training trial. In the test session, each mouse is placed back into this environment and the time between onset of exploration and initiation of drinking from the water tube is scored as a drinking latency. Learning is inferred if the animal finds the water tube more rapidly than an animal that had not been exposed previously to this environment. At that time, the WF task provides a measure of memory related mainly to the spatial construction of the test apparatus and to the specific object (water tube) in it. The water-finding performance during the test trial is thought to be based on latent learning, because the animals are deprived of water only before the test trial in order to promote recall of the location of the water tube to which they had been exposed in the training trial. Thus, the WF task may be advantageous in evaluating memory without manipulating reinforcers, although it can be improved upon.

Animals↗

Cortical areas supporting category learning identified using functional MRI.

Functional MRI was used to identify cortical areas involved in category learning by prototype abstraction. Participants studied 40 dot patterns that were distortions of an underlying prototype and then, while functional MRI data were collected, made yes-no category judgments about new dot patterns. The dot patterns alternated between ones mostly requiring a "yes" response and ones mostly requiring a "no" response. Activity in four cortical areas correlated with the category judgment task. A sizeable posterior occipital cortical area (BA 17/18) exhibited significantly less activity during processing of the categorical patterns than during processing of noncategorical patterns. Significant increases in activity during processing the categorical patterns were observed in left and right anterior frontal cortex (BA 10) and right inferior lateral frontal cortex (BA 44/47). Decreases in activation of visual cortex when categorical patterns were being evaluated suggest that these patterns could be processed in a more rapid or less effortful manner after the prototype had been learned. Increases in prefrontal activity associated with processing categorical patterns could be related to any of several processes involved in retrieving information about the learned exemplars.

Adult↗

Differential effects of subdiaphragmatic vagotomy on NaCl-induced aversion learning.

The vagus nerve has been proposed in numerous studies as one of the peripheral mechanisms involved in drug-induced taste aversion learning, although available data have been controversial. The differential results obtained in the present series of experiments with vagotomy and NaCl-induced short-term and long-term aversion learning suggest that the vagal system plays a decisive role in tasks requiring the rapid detection of an aversive substance in the gastrointestinal tract (short-term tasks). In contrast, this mechanism appears to be unnecessary in long-term tasks, where learning may be mediated by alternative slower-acting peripheral mechanisms such as the humoral system.

Animals↗

New tools for learning.

In the last twenty-five years more has been learned about the human brain than in the past history of mankind. Through the use of new technologies such as PET and CAT scans and functional MRI's, it is now possible to see and learn much about the human brain while it is in the process of thinking. The research of neuroscientists, such as Marian Diamond, has demonstrated that the brain changes physiologically as a result of learning and experience--for better or worse--and that plasticity can continue throughout the lifespan. It appears that there are particular kinds of environments that are most conducive to the development of good mental equipment. They are positive, nurturing, stimulating, and encourage action and interaction. Many of the most effective schools and training programs have created such high-challenge low-threat environments. It is also very clear that intelligence is not a static structure, but an open, dynamic system that can continue to develop throughout life. This understanding is being utilized not only in school systems but in the workplace, where training programs show that even at the adult level people are able to develop their intelligence more fully. Corporations such as Motorola have implemented programs in which they are training their employees, managers, and executives to think, problem-solve and create more effectively using strategies developed by such educational innovators as Reuven Feurstein, J.P. Guilford, and Edward de Bono. A most recent development is in the new kinds of technology that make it possible for people to take responsibility for their own learning as they access and process information through the internet, communicate with experts anywhere in the world, and use software that facilitate higher order thinking and problem-solving. Computers are in no way replacing teachers, but rather these new tools allow them to spend more time being facilitators, mentors, and guides. As a result, teachers and students are able more often to collaborate on creating new knowledge as well as mastering the basics. As technology becomes more ubiquitous, there is growing recognition of the importance of the arts in humanizing the curriculum. "More high-tech, more need for high-touch" is becoming the by-word of many schools. They recognize that the arts are not only culturally important and civilizing influences, but they can facilitate the learning of almost any subject. I believe that these four concepts--the plasticity of the brain, the modifiability of intelligence, the use of technology as a powerful new tool for learning, and the renaissance of the arts in education--have major implications specifically for educational systems and generally for the future of our world. In this time of rapid change, leading-edge educational systems are equipping people with the ability to learn, unlearn, and relearn continually. They are giving students meaningful opportunities to apply what they have learned in order to turn information into knowledge. And--of critical importance if any of this is to lead to a healthy future--they are helping students to learn to use knowledge responsibly, ethically, and with integrity. Furthermore, they are involving students in experiences that develop compassion and altruism in the process of their education. Our complex world urgently needs more people who have developed their fullest potential in mind, body, and spirit.

Adult↗

Context-response linkage.

Brindley (1969) proposed that we initially generate movements "consciously," under higher cerebral control. As the movement is practiced, the cerebellum learns to link within itself the context in which the movement is made to the lower level movement generators. Marr, (1969) Albus (1971), and Ito (1972) proposed that the linkage is established by a special input from the inferior olive, which plays upon an input-output element within the cerebellum during the period of the learning. When the linkage is complete, the occurrence of the context (represented by a certain input to the cerebellum) will trigger (through the cerebellum) the appropriate motor response. The "learned" movement is distinguished from the "unlearned" conscious movement by being automatic, rapid, and stereotyped. Another important variable can be added to the idea of the context-response linkage: novel combinations of downstream elements. With regard to the motor system, this could explain how varied combinations of muscles may become active in precise time-amplitude specifications so as to produce coordinated movements appropriate to specific contexts. This chapter further extends this idea to the premotor parts of the brain and their role in cognition. These areas receive influences from the cerebellum and are active both in planning movements that are to be executed and in thinking about movements that are not be executed. Evidence shows that the cerebellar output extends even to what has been characterized as the ultimate frontal planning area, the "prefrontal" cortex, area 46. The cerebellum thus may be involved in context-response linkage and in response combination even at these higher levels. The implication would be that, through practice, an experiential context would automatically evoke a certain mental action plan. The plan would be in the realm of thought and could-but need not-lead to execution. The specific cerebellar contribution would be one of the context linkage and the shaping of the response through trial and error learning. The prefrontal and premotor areas could still plan without the help of the cerebellum, but not so automatically, rapidly, stereotypically, so precisely linked to context, or so free or error. Nor would their activities improve optimally with mental practice.

Animals↗

Acceleration of visually cued conditioned fear through the auditory pathway.

Defensive responses elicited by sensory experiences are critical for survival. Mice acquire a conditioned fear response rapidly to an auditory cue but slowly to a visual cue, a difference in learned behavior that is likely to be mediated by direct projections to the lateral amygdala from the auditory thalamus but mainly indirect ones from the visual thalamus. Here, we show that acquisition of visually cued conditioned fear is accelerated in 'rewired' mice that have retinal projections routed to the auditory thalamus. Visual stimuli induce expression of the immediate early gene Fos (also known as c-fos) in the auditory thalamus and the lateral amygdala in rewired mice, similar to the way auditory stimuli do in control mice. Thus, the rewired auditory pathway conveys visual information and mediates rapid activity-dependent plasticity in central structures that influence learned behavior.

Amygdala↗

Is tube-escape learning by protozoa associative learning?

The ciliate protozoa, Stentor and Paramecium, have been reported to escape from the bottom end of narrow capillary tubes into a larger volume of medium with increasing rapidity over the course of trials. This change in behavior has been considered an apparent example of associative learning. This decrease in escape time is not due to a change in the protozoa's environment, their swimming speed, frequency of ciliary reversals, or the proportion of time spent forward or backward swimming. Instead, most of the decrease results from a decrease in the proportion of time spent in upward swimming. However, a similar decrease in upward swimming occurs when the task is altered to require escape from the upper end of the capillary tubes. Because the protozoa exhibit the same change in behavior regardless of the reinforcing stimulus, tube-escape learning is not associative learning.

Animals↗