PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Contrastive learning”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 469 records · Page 26Linked to original sources
PubMed1989

Lexical agraphia in the Japanese language. Pure agraphia for Kanji due to left posteroinferior temporal lesions.

A new syndrome of 'pure agraphia for Kanji' is described in 3 Japanese subjects with lesions in the left posteroinferior temporal region. Kanji (ideogram or morphogram) can be compared with orthographically irregular or ambiguous words in some European languages, since it is impossible to write Kanji characters unless each one of them is learned and memorized. In contrast, Kana (phonogram or syllabogram) words are comparable with orthographically regular words or nonsense words, because the Kana writing system depends on strict phonological rules (almost one-to-one correspondence between syllable and syllabogram). We conclude that 'lexical agraphia' reported in European languages can also be observed in the Japanese language where it is expressed as 'pure agraphia for Kanji'. 'Lexical agraphia' is a useful concept with general application regardless of language system.

Aged↗
PubMed2005

Neural substrates of phonemic perception.

The temporal lobe in the left hemisphere has long been implicated in the perception of speech sounds. Little is known, however, regarding the specific function of different temporal regions in the analysis of the speech signal. Here we show that an area extending along the left middle and anterior superior temporal sulcus (STS) is more responsive to familiar consonant-vowel syllables during an auditory discrimination task than to comparably complex auditory patterns that cannot be associated with learned phonemic categories. In contrast, areas in the dorsal superior temporal gyrus bilaterally, closer to primary auditory cortex, are activated to the same extent by the phonemic and nonphonemic sounds. Thus, the left middle/anterior STS appears to play a role in phonemic perception. It may represent an intermediate stage of processing in a functional pathway linking areas in the bilateral dorsal superior temporal gyrus, presumably involved in the analysis of physical features of speech and other complex non-speech sounds, to areas in the left anterior STS and middle temporal gyrus that are engaged in higher-level linguistic processes.

Acoustic Stimulation↗
PubMed2004

Why good guys wear white.

Affect is a somewhat abstract concept that is frequently linked to physical metaphor. For example, good is often depicted as light (rather than dark), up (rather than down), and moving forward (rather than backward). The purpose of our studies was to examine whether the association between stimulus brightness and affect is optional or obligatory. In a series of three studies, participants categorized words as negative or positive. The valence of the words and the brightness of the letters were varied orthogonally. In Studies 1, 2, and 3, we found that categorization was inhibited when there was a mismatch between stimulus brightness (e.g., light) and word valence (e.g., negative). Studies 4 and 5 reveal boundary conditions for the effect. The studies suggest that, when making evaluations, people automatically assume that bright objects are good, whereas dark objects are bad.

Affect↗
PubMedDate not supplied

Effects of a peer-mediated phonological skill and reading comprehension program on reading skill acquisition for middle school students with reading disabilities.

The purpose of this study was to examine the effect of a peer-mediated instructional approach on the teaching of phonological skills and reading comprehension for middle school (sixth- to eighth-grade) students with reading disabilities. All students (n = 38) were identified as having learning disabilities and reading at the third-grade level or below. One group was taught using a peer-mediated phonological skill program, Linguistics Skills Training (LST), and a peer-mediated reading comprehension program, Peer Assisted Learning Strategies (PALS). The contrast group was taught in the more traditional whole-class format using a widely implemented remedial reading program. The results showed significant differences between conditions, with students receiving the LST/PALS instruction outperforming the contrast group on Letter-Word Identification, Word Attack, and Passage Comprehension using the Woodcock-Johnson Test of Achievement-III. Furthermore, large effect sizes for growth were found on Letter-Word Identification, Word Attack, and Passage Comprehension for the LST/PALS treatment group. No differences were found between conditions for reading fluency. Findings are discussed in regard to instruction delivery format (peer tutoring vs. whole class) with respect to best practices for middle school students with reading disabilities.

Child↗
PubMed1992

An exploratory examination of the Parent-initiated Motivational Climate Questionnaire.

The purpose of this study was to examine the factor structure and internal reliability of the Parent-initiated Motivational Climate Questionnaire among 112 boys and 98 girls, young adolescents, and older adolescents. The questionnaire had a meaningful 3-factor structure and showed acceptable internal reliability. There was a significant difference between how boys and girls perceived their parents' reactions to their learning new physical skills. In contrast to boys, girls thought that both their mothers and fathers focused on improvement and self-satisfaction during the learning process and deemphasized learning without effort and worrying about making mistakes. Age did not significantly affect the perceptions the individuals had of their parents' convictions about their learning in the physical domain.

Adolescent↗
PubMed1999

Shifting the paradigm in tuberculosis control: illustrations from India.

Drawing on literature from India and key contributions from social science, this paper asks and attempts to answer the question 'who is to blame for treatment failures in TB'? Some key lessons emerge: effective tuberculosis control cannot be achieved so long as the disease is considered in isolation from the social processes that maintain it, create the conditions facilitating its spread and act as barriers to care. Insights into the economic and social burdens incurred with a diagnosis of TB are essential to understand why many patients, especially the most disadvantaged, are unable to comply with treatment regimens. TB and health care interventions need to be appropriate to the health service contexts in which they are applied, and sensitive to the competing demands, needs and priorities of people's lives. The paper argues for the need to reorient TB control programmes towards enabling patients to obtain care. The problem of access emerges as central to people's ability to obtain and maintain appropriate therapy. Examples and characteristics of successful non-governmental projects, from which policy makers, programmers and practitioners could learn, are outlined and contrasted with more rigid directly observed treatment approaches. We conclude that treatment failures are not patient failures, and that TB control programmes need to address the social dimensions of TB, and adhere to the principles of good TB care, with the same commitment that is devoted to ensuring patients follow treatment guidelines. We suggest a paradigm shift away from a focus on diseased patients towards enabling health in the community.

Antitubercular Agents↗
PubMed2000

Dissociating entorhinal and hippocampal involvement in latent inhibition.

This study used anatomical cues to suggest a functional dissociation between the roles of the entorhinal cortex and the hippocampus in learning. The authors proposed that the highly convergent inputs to the entorhinal cortex indicate this region may be particularly important for selecting or compressing information. This hypothesis was tested in rabbits (Oryctolagus cunniculus) trained on an associative learning task that is a common index of stimulus selection. In this task, known as latent inhibition, preexposure to a stimulus (such as a tone) leads to slowed learning when the same tone is subsequently paired with an outcome (such as an airpuff to the eye). As hypothesized, rabbits with neurotoxic lesions of the entorhinal cortex failed to show slowed learning following preexposure (no latent inhibition) and learned the association faster than control rabbits. In contrast, hippocampal-lesioned animals showed normal (slowed) learning.

Animals↗
PubMed2001

Early childhood television viewing and adolescent behavior: the recontact study.

In this Monograph, we report the follow-up of 570 adolescents who had been studied as preschoolers in one of two separate investigations of television use. The primary goal of the study was to determine the long-term relations between preschool television viewing and adolescent achievement, behavior, and attitudes. Using a telephone interview and high school transcripts, we assessed adolescent media use; grades in English, science, and math; leisure reading; creativity; aggression; participation in extracurricular activities; use of alcohol and cigarettes; and self-image. In each domain, we tested theories emphasizing the causal role of television content (e.g., social learning, information processing) as contrasted with those theories positing effects of television as a medium, irrespective of content (e.g., time displacement, pacing, interference with language). The results provided much stronger support for content-based hypotheses than for theories emphasizing television as a medium; moreover, the patterns differed for boys and girls. Viewing educational programs as preschoolers was associated with higher grades, reading more books, placing more value on achievement, greater creativity, and less aggression. These associations were more consistent for boys than for girls. By contrast, the girls who were more frequent preschool viewers of violent programs had lower grades than those who were infrequent viewers. These associations held true after taking into account family background, other categories of preschool viewing, and adolescent media use. One hypothesis accounting for the sex differences is that early experiences, such as television viewing, have greater effects when they counteract normative developmental trends and predominant sex-typed socialization influences than when they reinforce them. Adolescents in the study used both television and print media to support ongoing interests. Television content (e.g., entertainment, sports, or world events) predicted extracurricular activities, role models, and body image. The only evidence for possible effects of television as a medium was the positive relation of total viewing to obesity for girls. The medium of television is not homogeneous or monolithic, and content viewed is more important than raw amount. The medium is not the message: The message is.

Adolescent↗
PubMed1976

Eyelid conditioning and intellectual level: effects of repeated acquisition and extinction.

Groups of college students and moderately retarded persons averaging approximately equal age received eight alternating phases of acquisition and extinction trials with an electric pulse as the unconditioned stimulus for classical eyelid conditioning. The two conditioning groups did not differ significantly in attaining the acquisition criterion during any phase and showed systematic improvement in approaching the maximal rate of acquisition. However, the college students exhibited abrupt extinction in every phase, in contrast to retarded subjects. "Learning to learn" in the retarded group was more marked across acquisition than across extinction phases. Random control groups of the two subject classes displayed equal relative frequencies of nonconditioned blinks. Some of the findings clearly contradict a stimulus-context hypothesis of differences in learning rate associated with IQ level.

Acoustic Stimulation↗
PubMed1995

Dissociation of the behavioral and subjective components of nitrogen narcosis and diver adaptation.

We investigated adaptation to nitrogen narcosis by compressing 11 highly experienced divers in a hyperbaric chamber to the equivalent of 54.6 meters of seawater once a day for 5 consecutive days. The behavioral component of narcosis was assessed with a serial choice-reaction time (RT) task, and the subjective component with a global magnitude estimate. Supplementary magnitude estimates were obtained with adjectives describing work effectiveness and body sensations. The results showed that there was no adaptation on the RT task, although learning was evident. In contrast, the global estimate dissociated from RT and showed clear adaptation by Day 3. The work effectiveness adjectives followed RT and did not show adaptation. Some body sensation adjectives showed clear adaptation, but others did not. These results lead to the conclusion that the anecdotal reports of adaptation by divers can probably be attributed to the subjective rather than the behavioral component of narcosis. Dissociation of these components suggests mediation by different brain mechanisms, and it is speculated that the gamma-aminobutyric acidA/benzodiazepine receptor complex, which has been implicated in both the anesthetic and anxiolytic properties of agents such as nitrous oxide, may be involved.

Adaptation, Physiological↗
PubMed1996

Learning and teaching in dermatology. A practitioner's guide.

BACKGROUND: The explosion of medical knowledge, the influence of communications technology, and the pressures for health care reform challenge dermatologists to learn efficiently and teach effectively. OBSERVATIONS: The vast body of material on teaching and learning in the education literature contrasts sharply with the limited information on these topics in the dermatology literature. Gaining an understanding of these approaches to learning provides a foundation for the design of personal continuing medical education plans and lesson plans for students. Practical teaching skills are emphasized in this review. CONCLUSIONS: Learning and teaching skills can be improved through study. Successful teaching often produces positive feedback, which can lead to renewed enthusiasm for educating clinicians in the field of dermatology.

Dermatology↗
PubMed1997

[Autobiographical memory loss following herpes encephalitis].

We report a patient with prominent autobiographical memory (ABM) impairment, and discussed possible mechanisms of her deficits. The patient was a 36-year-old woman who suffered from herpes simplex encephalitis in November 1994. Four months after the onset, the neuropsychological examination disclosed that her intelligence, attention, language and frontal lobe functions were normal. Moderate anterograde amnesia was evident for visual materials, and she showed difficulties in retrieving visual images. Deficits in verbal learning were minimal. In contrast, her retrograde amnesia (RA) was severe. Further analyses clarified that memory for public events and personal semantic memory were relatively well preserved whereas ABM was severely impaired with no evidence of temporal gradient. Her performance on the ABM questionnaire was even worse than that of alcoholic Korsakoff patients. Interestingly, however, deficits in memory for public events also emerged when questions were presented with pictures instead of ordinary verbal questionnaires. The results suggest that her principle deficits consisted in utilizing visual information of the past events. Her access to and manipulation of the past visual representation/images were impaired. Consequently, her deficits were almost exclusive to ABM because visual information is most crucial for ABM. This material specific ABM impairment demonstrated in the present patient could be differentiated from nonspecific retrograde amnesia observed in typical focal RA patients. MRI, SPECT and PET demonstrated that the present patient had lesions basically in the right hemisphere, specifically in the medical temporal area including the hippocampus.

Adult↗
PubMed1998

A mental route to motor learning: improving trajectorial kinematics through imagery training.

There are contrasting reports upon the level of effectiveness of motor imagery in learning new motor skills, but there is general consensus that motor imagery can lead to improvements in performance, especially in combination with physical practice. In the present study we examined the effectiveness of motor imagery in the acquisition of movement invariants in two grapho-motor trajectorial learning tasks with differing visuospatial components: 'Ideogram drawing' and 'connecting circles'. Two subject groups were studied: An imagery group, which underwent 10 min of motor imagery training and a control group, which practised a control visuomotor task over the same period of time. The results showed that imagery training alone enabled the subjects to achieve a significant approach to movement isochrony as well as a significant shifting of peak velocity toward the target. After a practice phase, both groups improved their performance, but the imagery group was still significantly faster than the control group. Furthermore, a series of tests measuring visual imagery abilities was administered to the subjects. There were however no significant relationships between the motor performance and the visual imagery ability levels of the subjects. It is concluded that motor imagery can improve the acquisition of the spatio-temporal patterns of grapho-motor trajectories and that there are different processes involved in visual and motor imagery.

Adult↗
PubMed1997

Probing striatal function in obsessive-compulsive disorder: a PET study of implicit sequence learning.

Positron emission tomography was employed to contrast the brain activation pattern in patients with obsessive-compulsive disorder (OCD) to that of matched control subjects while they performed an implicit learning task. Although patients and control subjects evidenced comparable learning, imaging data from control subjects indicated bilateral inferior striatal activation, whereas OCD patients did not activate right or left inferior striatum and instead showed bilateral medial temporal activation. The findings further implicate corticostriatal dysfunction in obsessive-compulsive disorder. Furthermore, when OCD patients are confronted with stimuli that call for recruitment of corticostriatal systems, they instead appear to access brain regions normally associated with explicit (conscious) information processing.

Adult↗
PubMed1995

Adaptive fuzzy control of unstable nonlinear systems.

This paper addresses the structure and an associated on-line learning algorithm of a feedforward multilayer connectionist network for realizing the basic elements and functions of a traditional fuzzy logic controller. The proposed Fuzzy Adaptive Learning Control Network (FALCON) can be contrasted with the traditional fuzzy logic control systems in their network structure and learning ability. An on-line structure/parameter learning algorithm, called FALCON-ART, is proposed for constructing the FALCON dynamically. The FALCON-ART can partition the input/output space in a flexible way based on the distribution of the training data. Hence it can avoid the problem of combinatorial growing of partitioned grids in some complex systems. It combines the backpropagation learning scheme for parameter learning and the fuzzy ART algorithm for structure learning. More notably, the FALCON-ART can on-line partition the input/output spaces, tune membership functions, and find proper fuzzy logic rules dynamically without any a priori knowledge or even any initial information on these. The proposed learning scheme has been successfully used to control two unstable nonlinear systems. They are the seesaw system and the inverted wedge system.

Algorithms↗
PubMed1997

Dietary gluten and learning to attend to redundant stimuli in rats.

The purpose of the present study was to assess the effect of a high-gluten diet against a gluten-free diet on learning stimulus-response relationships in rats. In the first phase of training rats learned to associate a stimulus light with responding on a particular response lever. In the second phase, the same rats were exposed to new, but redundant stimuli to guide responding (a tone and houselight). Probe trials, involving only new stimuli, revealed that rats fed a gluten-free diet displayed a "blocking" effect. That is, gluten-free rats did not learn to associate these new stimuli with particular responses. In contrast, high-gluten rats very quickly learned to use these redundant stimuli to guide responding. Subsequent phases of training demonstrated, however, that this group difference could be removed. The present findings are discussed in the context of the possible links between dietary gluten and schizophrenia.

Acoustic Stimulation↗
PubMed2005

Participation of octopaminergic reward system and dopaminergic punishment system in insect olfactory learning revealed by pharmacological study.

Biogenic amines play major roles in the regulation of behavior in vertebrates and invertebrates. Previous studies in honey bees and fruit-flies Drosophila suggested that octopamine (OA, invertebrate counterpart of noradrenaline) and dopamine (DA) participate in appetitive olfactory conditioning with sucrose reward and aversive olfactory conditioning with electric shock punishment, respectively. In order to determine whether the effects of the two chatecholamines on electric shock and sugar learning can be generalized to other kinds of appetitive and aversive reinforcers, we studied the effects of OA and DA receptor antagonists on appetitive olfactory learning with water reward, and aversive olfactory learning with saline punishment in the cricket Gryllus bimaculatus. Crickets injected with epinastine or mianserin, OA receptor antagonists, into the hemolymph exhibited an impairment of appetitive learning with water reward, while aversive learning with saline punishment remained intact. In contrast, fluphenazine, chlorpromazine or spiperone, DA receptor antagonists, impaired aversive learning without affecting appetitive learning. This finding, combined with findings in previous studies, suggests that the octopaminergic reward system and dopaminergic punishment system participate in insect olfactory learning with various appetitive and aversive reinforcements.

Animals↗