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Interpreting open- and closed-loop transfer relations between cardiorespiratory parameters: lessons learned from a computer model of beat-to-beat cardiovascular regulation.

A computer model of cardiovascular control has been developed based on the response characteristics of cardiovascular control components derived from experiments in animals and humans. Results from the model were compared to those obtained experimentally in humans, and the similarities and differences were used to identify both the strengths and inadequacies of the concepts used to form the model. Findings were confirmatory of some concepts but contrary to some which are firmly held in the literature, indicating that understanding the complexity of cardiovascular control probably requires a combination of experiments and computer models which integrate multiple systems and allow for determination of sufficiency and necessity.

Computer Simulation↗

Mechanisms of generalization in perceptual learning.

Learning in many visual perceptual tasks has been shown to be specific to practiced stimuli, while new stimuli have to be learned from scratch. Here we demonstrate generalization using a novel paradigm in motion discrimination where learning has been previously shown to be specific. We trained subjects to discriminate directions of moving dots, and verified the previous results that learning does not transfer from a trained direction to a new one. However, by tracking the subjects' performance across time in the new direction, we found that their speed of learning doubled. Therefore, we found generalization in a task previously considered too difficult to generalize. We also replicated, in a second experiment, transfer following training with 'easy' stimuli, when the difference between motion directions is enlarged. In a third experiment we found a new mode of generalization: after mastering the task with an easy stimulus, subjects who have practiced briefly to discriminate the easy stimulus in a new direction generalize to a difficult stimulus in that direction. This generalization depends on both the mastering and the brief practice. The specificity of perceptual learning and the dichotomy between learning of 'easy' versus 'difficult' tasks have been assumed to involve different learning processes at different cortical areas. Here we show how to interpret these results in terms of signal detection theory. With the assumption of limited computational capacity, we obtain the observed phenomena--direct transfer and acceleration of learning--for increasing levels of task difficulty. Human perceptual learning and generalization, therefore, concur with a generic discrimination system.

Discrimination, Psychological↗

Processing of interactive and noninteractive pictures in PA learning by retarded persons.

Retarded persons, at two MA levels, were exposed to a list of paired-associates (PAs) in which the stimulus terms were picture compounds of one animate and one inanimate object. One-half of the subjects in each MA group learned the associations with the stimulus components presented in meaningful interaction, and half learned the associations with the components depicted in noninteraction. Stimulus interaction facilitated list acquisition by the higher MA but not by the lower MA subjects. Transfer tests following PA learning indicated that the interactive stimulus components had been processed as units by the higher MA subjects, suggesting that these individuals may have spontaneously elaborated the interactive-stimulus components.

Cognition↗

Automatic category search and its transfer: aging, type of search, and level of learning.

We examined the site of learning as a function of task type and age. Two experiments examined whether learning in semantic category search is exclusive to trained elements of categories or generalizable to other elements of the trained categories. Specifically, we examined how practice searching for small subsets of exemplars from taxonomic categories transferred to untrained elements of those categories. Young and old adults received extensive practice on memory search (Experiment 1) or visual search (Experiment 2) tasks. Participants then transferred to conditions assessing whether learning was exclusive to the trained words or generalizable to other elements of the trained categories. The site of learning in memory search appears to be at the category level for both young and old adults. Level of learning in visual search appears to differ as a function of age. Young adults' learning generalizes to the category level, whereas older adults' learning is specific to the trained words.

Adolescent↗

Changes in pattern discrimination learning induced by visual deprivation in normal and commissurotomized pigeons.

The effect of monocular (MD), binocular (BD) and alternating monocular (AMD) deprivation on monocular pattern discrimination learning and interocular transfer was investigated in pigeons reared with intact and sectioned supraoptic decussation (DSO). In BD and AMD animals acquisition and interocular transfer of two different pattern discrimination problems remained as good as in the control animals (CO). Monocularly deprived animals (MDE) required significantly more trials to learn the discriminations through the deprived eye, when it was trained first, and interocular transfer from the deprived to the experienced eye was absent. However, if the experienced eye was trained first (MED), learning with the deprived eye was at least as rapid as with the experienced eye. This indicates positive interocular transfer from the experienced to the deprived eye. Interocular transfer of pattern discriminations was completely blocked by section of the DSO in both adults (DSOad) and newly hatched animals (DSOjuv). The elimination of binocular interaction by commissurotomy from the beginning of the postnatal life failed to produce an impaired pattern discrimination learning in monocularly deprived animals.(MD+DSO). The results are discussed in terms of competition between the projections from both eyes in the visual Wulst.

Animals↗

The contingencies of organizational learning in long-term care: factors that affect innovation adoption.

We apply the theoretical frameworks of knowledge transfer and organizational learning, and findings from studies of clinical practice guideline (CPG) implementation in health care, to develop a contingency model of innovation adoption in long-term care (LTC) facilities. Our focus is on a particular type of innovation, CPGs designed to improve the quality of LTC. Our interest in this area is founded on the premise that the ability of LTC organizations to adopt and sustain the use of innovations like CPGs is contingent on the initial capacity these institutions have to learn about them, and on the presence of factors that contribute to capacity building at each stage of innovation adoption. Based on our review of relevant theory, we develop a set of fifteen testable propositions that relate factors operating at the guideline, individual, organizational, and environmental levels in LTC institutions to stages of guideline adoption/transfer. Our model offers insights into the complexities of adopting and sustaining innovations in LTC facilities particularly, in health care organizations specifically, and in service organizations generally.

Diffusion of Innovation↗

Learning from Worked-Out Examples: The Effects of Example Variability and Elicited Self-Explanations

It was investigated to what extent example variability and the elicitation of sophisticated self-explanations foster the acquisition of transferable knowledge by learning from worked-out examples. In addition, it was asked whether the effects of these factors are moderated by the learners' levels of prior topic knowledge. To this end, we had 56 apprentices from a bank learn calculation of compound interest and real interest. They were randomly assigned to the four conditions of a 2 x 2-factorial design (factor 1: uniform vs. multiple examples; factor 2: spontaneous vs. elicited self-explanations). The learning results were measured by a post-test comprising near-transfer problems and far-transfer problems. It was found that the acquisition of transferable knowledge can be supported by eliciting self-explanations. In the case of near transfer, especially learners with low levels of prior topic knowledge profited from the elicitation procedure. On the whole, the findings underline the "causal" relevance of the quality of self-explanations for knowledge acquisition by learning from worked-out examples. The assumption that multiple examples foster transfer performance, at least when sophisticated self-explanations are elicited, was not supported. Copyright 1998 Academic Press.

Journal Article↗

Oral healthcare of clients with learning disability: changes following relocation from hospital to community.

OBJECTIVE: To investigate changes in the oral healthcare of adults with learning disability after transference from long stay hospital care to community-based care. SUBJECTS: Adults with learning disability who were former residents of a single long stay hospital and who had been resettled into the community during the period April 1995 to April 1998. DESIGN: Structured questionnaire with a covering letter sent to community-based carers. Hospital notes were reviewed to assess oral healthcare received as in-patients. RESULTS: There was a 68% response rate to the questionnaire from community-based carers with details obtained from 106 out of a possible 157 subjects. As residents in the hospital, all subjects were examined regularly by a dentist--yearly for edentulous and six-monthly for dentate individuals. However, attendance patterns were less regular as residents in the community. In the community, individuals were also less likely to receive operative dental treatment. Although oral hygiene regimes were generally on a daily basis only 37% of the subjects and/or their carers had received oral health education from dental professionals in the community. CONCLUSION: Changes from institutional living to community-based housing for adults with learning disability may be associated with changes in dental attendance and treatment patterns.

Adult↗

Visually guided catching and tracking skills in pigeons: A preliminary analysis.

Research on reaching, tracking, and catching in the pigeon has been hampered by limitations of technology. A new system was developed in which the target was a small rectangle presented on a video display terminal and the pecking response was detected with touch technology. The target moved up and down vertically with sinusoidal velocity. A coincidence between the location of the pigeon's beak and the cursor produced reinforcement. The pigeon pecked ahead and behind the target, but most pecks occurred behind the target so the dominant tracking strategy was lagging. The pigeon was adept at "catching" the target at many locations throughout the trajectory. Transfer of motor learning was tested on probe trials during which the trajectory changed from vertical to horizontal. On transfer trials the pigeons' dominant pattern of pecking immediately shifted from vertical to horizontal. The motor skill displayed by the pigeons was flexible and adaptive, suggesting that the pigeons had learned to track the cursor.

Journal Article↗

On learning complex procedural knowledge.

Lewicki, Czyzewska, and Hoffman (1987) demonstrated learning without awareness in a visual search task. Rules determined target location on every seventh trial on the basis of target locations in the preceding six trials. Learning was demonstrated by negative transfer effects when the rules were changed. When questioned afterwards, the subjects could not describe the rules and denied awareness of them. This experiment was designed to replicate that of Lewicki et al. and to test several hypotheses about this apparent learning without awareness. Transfer conditions were included to determine whether rule learning was primarily perceptual or motor. The present assessment of awareness was based on an objective definition of awareness, rather than a subjective definition as in Lewicki et al.'s study. Their effect was replicated, and the transfer conditions revealed that learning relied on perceptual aspects of the task. The objective measure of awareness provided further evidence that subjects were unaware of the rules.

Adult↗

An intervention programme for children with moderate learning difficulties.

BACKGROUND: Children with learning difficulties typically demonstrate problems generalising what they have learned in specific contexts to new situations. Intervention programmes that teach children regulatory skills have been shown to overcome these problems for children with reading difficulties. This study applies the principles that underlie such interventions to the design of a programme for children with more general learning difficulties. AIM: The aim of the study reported here was to design and evaluate an intervention programme which would facilitate the transfer of skills learned over the course of the intervention to different types of task. SAMPLE: A total of 41 children (aged 13-16 yrs; 14 females, 27 males) with moderate learning difficulties participated in the intervention programme. METHOD: The children participated in a twelve-week intervention programme designed to promote regulatory strategies over a range of activities. The children worked in pairs and were guided by an adult who provided explicit instruction and modelled appropriate strategies. The children were assessed before and after the programme to determine whether improvements in strategic behaviour were evident and whether this generalised to new situations. RESULTS: Gains made in regulatory skills over the course of the intervention were accompanied by improvements in other performance measures such as reading and IQ. CONCLUSIONS: Even after a relatively short intervention, which focused on the development of regulatory skills, significant improvements on a range of tasks were observed for a group of children with moderate learning difficulties.

Adolescent↗

Gene transfer of hepatocyte growth factor gene improves learning and memory in the chronic stage of cerebral infarction.

There is no specific treatment to improve the functional recovery in the chronic stage of ischemic stroke. To provide the new therapeutic options, we examined the effect of overexpression of hepatocyte growth factor (HGF) in the chronic stage of cerebral infarction by transferring the HGF gene into the brain using hemagglutinating virus of Japan envelope vector. Sixty rats were exposed to permanent middle cerebral artery occlusion (day 1). Based on the sensorimotor deficits at day 7, the rats were divided equally into control vector or HGF-treated rats. At day 56, rats transfected with the HGF gene showed a significant recovery of learning and memory in Morris water maze tests (control vector 50+/-4 s; HGF 33+/-5 s; P<0.05) and passive avoidance task (control vector 132.4+/-37.5 s; HGF 214.8+/-26.5 s; P<0.05). Although the total volume of cerebral infarction was not related to the outcome, immunohistochemical analysis for Cdc42 and synaptophysin in the peri-infarct region revealed that HGF enhanced the neurite extension and increased synapses. Immunohistochemistry for glial fibriary acidic protein revealed that the formation of glial scar was also prevented by HGF gene treatment. Additionally, the number of the arteries was increased in the HGF group at day 56. These data demonstrated that HGF has a pivotal role for the functional recovery after cerebral infarction through neuritogenesis, improved microcirculation, and the prevention of gliosis. Our results also provide evidence for the feasibility of gene therapy in the chronic stage of cerebral infarction.

Animals↗

Perceptual learning in motion discrimination that generalizes across motion directions.

When human subjects discriminate motion directions of two visual stimuli, their discrimination improves with practice. This improved performance has been found to be specific to the practiced directions and does not transfer to new motion directions. Indeed, such stimulus-specific learning has become a trademark finding in almost all perceptual learning studies and has been used to infer the loci of learning in the brain. For example, learning in motion discrimination has been inferred to occur in the visual area MT (medial temporal cortex) of primates, where neurons are selectively tuned to motion directions. However, such motion discrimination task is extremely difficult, as is typical of most perceptual learning tasks. When the difficulty is moderately reduced, learning transfers to new motion directions. This result challenges the idea of using simple visual stimuli to infer the locus of learning in low-level visual processes and suggests that higher-level processing is essential even in "simple" perceptual learning tasks.

Humans↗

Positive effect of surgical experience with implants on second-stage implant survival.

This Dental Implant Clinical Research Group study defined a learning curve for dental implant placement. Implants placed by inexperienced surgeons (< 50 implants) failed twice as often as those placed by experienced surgeons (> or = 50 implants). Implants placed during the first 6, 8, 10, 12, and 16 cases were compared with all others. The greatest difference was seen between the first nine cases and all others (P = .001), with later cases failing significantly less often. Inexperienced surgeons had more failures in the first nine cases (5.9%) than more experienced surgeons (2.4%). Surgeons with little or no previous experience must expect a definite learning curve. Previous experience may transfer and result in a shallower learning curve for subsequent systems.

Clinical Competence↗

Hyperspecificity in visual implicit learning: learning of spatial layout is contingent on item identity.

Humans conduct visual search faster when the same display is presented for a 2nd time, showing implicit learning of repeated displays. This study examines whether learning of a spatial layout transfers to other layouts that are occupied by items of new shapes or colors. The authors show that spatial context learning is sometimes contingent on item identity. For example, when the training session included some trials with black items and other trials with white items, learning of the spatial layout became specific to the trained color--no transfer was seen when items were in a new color during testing. However, when the training session included only trials in black (or white), learning transferred to displays with a new color. Similar results held when items changed shapes after training. The authors conclude that implicit visual learning is sensitive to trial context and that spatial context learning can be identity contingent.

Adolescent↗