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PubMed2006

Neural activation during successful and unsuccessful verbal learning in schizophrenia.

Successful and unsuccessful intention to learn words was assessed by means of event-related functional MRI. Eighteen patients with schizophrenia and 15 healthy control participants were scanned while being given two word lists to read and another seven to learn with immediate recall. Neural activation patterns were segregated according to whether words were subsequently recalled or forgotten and these conditions were contrasted with each other and reading. Compared to controls, patients with schizophrenia showed deficits with regard to neural recruitment of right hippocampus and of cerebellar structures during successful verbal learning. Furthermore, a reversal of activated structures was evident in the two groups: Controls showed activation of right frontal and left middle temporal structures during the unsuccessful intention to learn. During successful learning, there was additional activation of right superior parietal lobule. In contrast, patients showed activation of right superior parietal lobule during unsuccessful and successful intention to learn. There were additional frontal and left middle temporal lobe activations during successful learning. We conclude that increased parietal activity may reflect a mechanism which compensates for the lack of hippocampal and cerebellar contributions to verbal learning in schizophrenia.

Adult↗
PubMed1996

Performance of healthy subjects and patients with resection from the anterior temporal lobe on matched tests of verbal and visuoperceptual learning.

We examined the equivalence of three matched forms of the Rey Auditory Verbal Learning Test (RAVLT) and three parallel forms of a new nonverbal analog, the Aggie Figures Learning Test (AFLT). One hundred and fourteen healthy subjects, primarily college students, were administered corresponding forms of the two tasks. For both tasks the three forms proved to be well-matched; as well, overall performance on the RAVLT was comparable to that on the AFLT. The two tasks were also administered to 23 patients with anterior resection from the left or right temporal lobe (ATL). Findings showed that right ATL patients were significantly impaired on the learning trials of the AFLT as compared to their learning on the RAVLT; they showed little forgetting of figures or words over a 20-min delay interval. By contrast, left ATL patients showed severe forgetting of words as compared to figures, but their learning curve for the RAVLT did not differ from that on the AFLT.

Adolescent↗
PubMed1995

On the interaction of prior knowledge and stimulus structure in category learning.

Contemporary theories of categorization propose that concepts are coherent in virtue of being embedded in a network of theories about the world. Those theories function to pick out some of the many possible features of a set of objects as most salient for purposes of classification, a process that is complex and still poorly understood (Murphy & Medin, 1985). Part of what makes this account incomplete is a lack of information as to (1) what makes a feature salient on a given occasion and (2) how feature salience interacts with category structure to determine the course of learning. We report on the results of three studies of category learning using complex schematic drawings to show that (1) the contrast set defined by one's initial encounters with category exemplars can be a source of individual differences in feature salience assignments; (2) such effects are short-lived in the face of clear evidence about actual feature diagnosticity; and (3) more robust prior hypotheses interact with category structure to either enhance learning or impede it. The enhancement occurs when the hypothesis emphasizes category-relevant features, even if the hypothesis is in fact incorrect. A hypothesis that assigns high salience to irrelevant features impedes learning. Learning does occur as feedback concerning category structure leads to enhanced salience for relevant features. Salience of irrelevant features remains high, however, suggesting that such learning as occurs involves augmentation and not total revision of the (incorrect) prior hypothesis.

Attention↗
PubMed1989

Pharmacological effects of indeloxazine, a new cerebral activator, on brain functions distinct from other cerebral metabolic enhancers.

The effects of indeloxazine hydrochloride [(+/-)-2-[(inden-7-yloxy)methyl]morpholine hydrochloride, YM-08054], a new cerebral metabolic enhancer, on learned behavior and central monoaminergic function were compared to those of other cerebral metabolic enhancers in animals. Indeloxazine enhanced passive learned behaviour in rats and ameliorated cerebral ischemia-induced learned disturbances in gerbils. Reserpine-induced hypothermia in mice, ponto-genicullo-occipital (PGO) waves in reserpinized cats and caudate spindle activity in cats were reduced by the administration of indeloxazine, suggesting that the drug possesses facilitatory effects on central monoaminergic systems. In contrast, piracetam, calcium-hopantenate, idebenone and bifemelane had no significant effect on learned behavior or central monoaminergic function, with the exception of bifemelane which antagonized reserpine-induced hypothermia. These results are in contrast to the findings that all tested cerebral metabolic enhancers, including indeloxazine, prolonged the survival time of mice subjected to anoxia. The greater effect of indeloxazine to other cerebral metabolic enhancers, in facilitating learned behavior, may be attributable to its broader effects on central monoaminergic systems.

Animals↗
PubMed2002

Nerve growth factor improves spatial learning and restores hippocampal cholinergic fibers in rats withdrawn from chronic treatment with ethanol.

The cholinergic septohippocampal pathway has long been known to be important for learning and memory. Prolonged intake of ethanol causes enduring memory deficits, which are paralleled by partial depletion of hippocampal cholinergic afferents. We hypothesized that exogenous supply of nerve growth factor (NGF), known to serve as a trophic substance for septal cholinergic neurons, can revert the ethanol-induced changes in the septohippocampal cholinergic system. Adult rats were given a 20% ethanol solution as their only source of fluid for 6 months. During the first 4 weeks after the animals were withdrawn from ethanol, they were intraventricularly infused with either NGF or vehicle alone via implanted osmotic minipumps. The vehicle-infused withdrawn animals showed impaired performance on a spatial reference memory version of the Morris water maze task, both during the task acquisition and on the retention test. In contrast, NGF-treated withdrawn rats were able to learn the task as well as controls, and significantly outperformed the vehicle-infused withdrawn rats. The histological analysis revealed that, in the latter group, the length density of fibers immunoreactive to choline acetyltransferase was reduced relative to control values by approximately 25%, as measured in the dentate gyrus and regio superior of the hippocampal formation. However, in NGF-treated withdrawn rats, the length density of these fibers was identical to that of control rats. These data provide support to the notion that NGF is capable of ameliorating memory deficits and restoring septohippocampal cholinergic projections following chronic treatment with ethanol.

Afferent Pathways↗
PubMed1980

Reward conditions and socioeconomic status in the learning of older adults.

It was hypothesized that older adults do not perform well in laboratory learning tasks, not so much because they do not learn well as because they are reluctant to demonstrate what they have learned by venturing responses when uncertain. This hypothesis was tested by contrasting the performance of older subjects who were rewarded for responding, right or wrong (experimental group) with subjects who were rewarded for only correct responses (control group). Older subjects from a wide range of SES levels learned most efficiently under the control condition. However, for older subjects from high SES vs low SES levels, differential results were obtained. The high SES subjects learned more efficiently under the control condition, whereas there was a trend for the low SES subjects to learn more efficiently under the experimental condition. The hypothesis therefore received at least partial support in this study.

Age Factors↗
PubMed1997

Representations of graphomotor trajectories in the human parietal cortex: evidence for controlled processing and automatic performance.

The aim of this study was to identify the cerebral areas activated during kinematic processing of movement trajectories. We measured regional cerebral blood flow (rCBF) during learning, performance and imagery of right-hand writing in eight right-handed volunteers. Compared with viewing the writing space, increases in rCBF were observed in the left motor, premotor and frontomesial cortex, and in the right anterior cerebellum in all movement conditions, and the increases were related to mean tangential writing velocity. No rCBF increases occurred in these areas during imagery. Early learning of new ideomotor trajectories and deliberately exact writing of letters both induced rCBF increases in the cortex lining the right intraparietal sulcus. In contrast, during fast writing of overlearned trajectories and in the later phase of learning new ideograms the rCBF increased bilaterally in the posterior parietal cortex. Imagery of ideograms that had not been practised previously activated the anterior and posterior parietal areas simultaneously. Our results provide evidence suggesting that the kinematic representations of graphomotor trajectories are multiply represented in the human parietal cortex. It is concluded that different parietal subsystems may subserve attentive sensory movement control and whole-field visuospatial processing during automatic performance.

Adult↗
PubMed1997

Effects of pivagabine on psychophysical performance and behavioural response in experimental models of stress.

The effect of pivagabine (4-[(2,2-dimethyl-1-oxopropyl)amino]butanoic acid, CAS 69542-93-4, Tonerg), a synthetic molecule with neuromodulatory activity, was evaluated on a series of behavioural parameters in rats exposed to various stimuli, with the aim of evaluating the response to stress (open field exploration, water maze, psychic conflict), conditioning (active and passive avoidance and avoidance retention, aggressiveness, extinction of conditioned responses), learning and performing of specific psychophysical tests (rota-rod, ballasted swimming, taut thread). Pivagabine induced significant improvement of stress-related tests by reducing the anxiety-producing reactions related to the various experimental settings. In conditioning tests an improvement in learning of conditioned responses was observed at lower dosages (10 and 50 mg/kg); an opposite effect was obtained with higher dosages (100 and 200 mg/kg). Pivagabine did not influence the retention nor the extinction of conditioned responses. Pivagabine induced a marked improvement of all motor performance tests in young and in aged animals. By contrast with benzodiazepines, pivagabine did not alter the ability of learning tasks, the motor performance and the aggressive behaviours. It is likely that the observed effects of pivagabine are mediated by inhibition of release of corticotropin-releasing factor, a neurohormone involved in stress-generating mechanisms.

Animals↗
PubMed2006

Impulsive decision-making: learning to gamble wisely?

A decade ago, Bechara et al. [Bechara, A., Damasio, A. R., Damasio, H., & Anderson, S. W. (1994). Insensitivity to future consequences following damage to human prefrontal cortex. Cognition, 50, 7-15] published a paper in Cognition, introducing a Gambling Task which was designed to mimic everyday decision-making. Since then, the task has been computerized, its decision-making components have been scrutinized, and it has been employed in various patient groups, such as pathological gamblers, substance abusers, and so forth. Time and again it has been shown that while normal controls perform well on the task, it is the various target populations under scrutiny who exhibit poor performance. Yet, as we show in this paper, a total of 46% of normal individuals exhibited poor performance on the task, indicating a lack of learning. We argue that while so much importance has been placed on contrasting patients with controls, perhaps the real emphasis should lie in distinguishing among different individual profiles of performance on the task, irrespective of clinical classification. Our basic recommendation is to look at the individual data, pool when you can, and only then to contrast groups.

Adult↗
PubMed2000

Reactions of nurses and therapists in mainstream health services to contact with people who have learning disabilities.

Government policy in the United Kingdom is to make the National Health Service accessible to all citizens, including those who hitherto may have relied on specialist services. It is recognized that the attitudes of health professionals can be a major influence in making this happen. To date there has been a paucity of research studies involving nurses and therapists, two of the largest groupings of health care workers. The present study contrasted the reactions of nurses and therapists to their contact with people who have learning disabilities, with those of staff working in specialist services for this client group, and with students who are not involved in health services. Over 1000 respondents - mainly university students on undergraduate or post-graduate courses - completed a written questionnaire. Although nurses and therapists had significantly less contact with people who had learning disabilities during their work than did staff in specialist services, there were no differences in terms of contact in personal life. In both instances their contacts were higher than those reported for non-healthcare students. However both nurses and therapists were significantly less confident in working with a patient who had learning disabilities as opposed to one with physical disabilities. By contrast, willingness for social contacts did not vary across the four groups although respondents with previous personal contact were significantly more willing for this than those with no prior contact. The results confirm that the form of contact is a more salient variable on staff attitudes than contact per se. Hence, changed reactions are more likely to come about from successful contacts in a work rather than social environment. The implications are discussed for initial and post-qualifying training courses, especially for suitable placement experiences. Suggestions are made for future research that focuses on increasing the expertise and confidence of nurses and therapists in working with patients who have learning disabilities.

Adolescent↗
PubMedDate not supplied

School functioning for the child with leukemia in continuous first remission: screening high-risk children.

It is well known in the literature that cancer creates educationally related barriers for all children, which may or may not contribute to clinically relevant school problems. The goal of this study was to obtain a base rate for the characteristic pattern of school functioning for children with leukemia, so that the children with the most serious difficulties might be discovered and given the different and flexible help needed. From 1988 through 1994, a questionnaire was administered annually to teachers of all leukemic children in our center. The 291 questionnaire were used to compare the school functioning of children with leukemia with that of matched controls chosen by each teacher as representative of the class as a whole, excluding special education and developmentally disabled students. This approach to matching was chosen as a control for socioeconomic factors as well. The study was conducted with all patients with leukemia entering the center residing in the region of Lombardy, attending school, and either in therapy or out of therapy. After initial treatment, the children with leukemia in our center as a group attended school regularly and willingly. Analyses of variance (ANOVAs) were conducted on the total scores and on scores for each of the subareas of learning, socialization, and emotionality. T-tests, were given to contrast individual item scores of patients with those of their matched controls. On most individual items, children with leukemia did not differ from their classmates. However, significant discrepancies between children with leukemia and their classmates appeared consistently year after year on overall total scores and on each of the three major subcomponents of the test (learning, socialization, and emotionality). The groups most affected were children who were cranially irradiated and children who were under 6 years of age at diagnosis. Children who have been irradiated and children diagnosed under 6 years of age have the greatest risk for difficulties in school functioning and are candidates for greater attention and preventive efforts.

Adaptation, Psychological↗
PubMed2004

Double dissociation of social and environmental stimulation on spatial learning and reversal learning in rats.

Environmental enrichment induces structural and biochemical changes in the brains of mammals that correlate with improved learning and memory. Research in rats suggests that social compared to inanimate stimulation might affect behavior differently, by acting upon dissociable neural substrates. Here we tested this hypothesis at the behavioral level by examining whether social and inanimate stimulation affect spatial memory formation and non-spatial discrimination reversal learning selectively. Spatial memory formation is known to depend on hippocampal-neocortical pathways, whereas reversal learning depends primarily on prefrontal cortico-striatal pathways. Male Lister hooded rats were housed singly or in groups of three in either small barren or large enriched cages, from weaning onwards. After 10 weeks of differential housing, spatial learning and memory were examined in the Morris water maze, followed by a series of tactile and odour discriminations, including discrimination reversal, in a two-choice discrimination task. Regardless of inanimate stimulation, social deprivation affected neither the acquisition of simple or complex discriminations, nor spatial memory formation, but was associated with impaired reversal learning in the two-choice discrimination task. By contrast, inanimate deprivation, regardless of social stimulation, affected neither acquisition nor reversal of two-choice discriminations, but selectively delayed the acquisition of spatial memory in the Morris water maze. This is the first demonstration of a double dissociation of early social and inanimate stimulation on two distinct behavioural functions that are mediated by dissociable underlying neural pathways. These findings strengthen the view that social and inanimate stimulation act, at least in part, upon dissociable neural substrates.

Animals↗
PubMed1996

Activation of human presupplementary motor area in learning of sequential procedures: a functional MRI study.

1. Using functional magnetic resonance imaging, we investigated the neural correlates of sequential procedural learning. During the test scans the subjects learned a new sequence (position or color) of button presses; during the control scans they pressed the buttons in any order. The comparison of the test and control scans was expected to reveal the neural activities related to learning, not sensory-motor processes. 2. We found that a localized area in what we regard to be the human homologue of the presupplementary motor area (pre-SMA) was particularly active for learning of new sequential procedures (either position or color sequences), not movements per se. 3. In contrast, the SMA proper (posterior to pre-SMA) was active for the performance of sequential movements, not learning. This was shown in another paradigm in which the subjects pressed the buttons in any order in the test scans and just watched the sequence in the control scans. 4. The learning-related pre-SMA region, which was consistent across different experiments in single subjects, was identified on only one side in each subject.

Humans↗
PubMed1998

Relationship between abnormal cholesterol synthesis and retarded learning in rats.

We examined the relationship between brain sterol composition and associative learning (classical conditioning of the eyeblink response) in newly weaned rats fed BM 15.766 (BM) for 4 months. This compound inhibits 7-dehydrocholesterol-delta7-reductase, which catalyzes the conversion of 7-dehydrocholesterol to cholesterol, the last step in the synthetic pathway. As countertreatment, half of the BM-treated rats were fed 2% cholesterol during the last 2 months. With BM, cholesterol concentrations declined 91% in plasma, but with cholesterol feeding, the levels increased 50% compared with baseline values. 7-Dehydrocholesterol, which was not detected at baseline, increased to 55% of plasma sterols with BM but decreased to 5% of total plasma sterols when cholesterol was added. With BM, brain cholesterol levels decreased 60% and did not increase after cholesterol was added. However, 7-dehydrocholesterol, which comprised 39% of brain sterols with BM, decreased to 31% (P < .05) when cholesterol was fed. Hydroxymethyl glutaryl coenzyme A (HMG-CoA) reductase activity in the liver increased 2.2-fold with BM and declined 95% after adding cholesterol, but did not change in the brain. BM treatment for 4 months prevented learning of the conditioned eyeblink response as compared with controls. In contrast, BM-treated rats supplemented with cholesterol acquired the conditioned eyeblink response. Chronic inhibition of 7-dehydrocholesterol-delta7-reductase reduced cholesterol and increased 7-dehydrocholesterol levels in plasma and brain, and was associated with impaired learning. Cholesterol feeding corrected plasma and hepatic sterol levels and reduced brain 7-dehydrocholesterol concentrations to reestablish normal learning.

Administration, Oral↗
PubMed1990

Hands-on laboratory experience in teaching-learning physiology.

Reactivation of several model 5 (vacuum tube) Grass polygraphs for active hands-on laboratory experiments by small student groups, in contrast to demonstrations and pretaped illustrations of physiological principles, resulted in remarkable rejuvenation of interest and excitement for learning in premed and introductory science classes at Taylor University. Accurate and perceptive observations were performed on the students themselves, each recording his own electrocardiogram, for example, as well as direct recordings from the pithed frog, the turtle heart, the anesthetized rabbit, and noninvasive recordings from students subjects during exercise. In the latter experiment, sweat recruitment patterns were recorded initially on the lower extremities, followed by successive appearances on thigh and abdomen and with final occurrence on the upper extremities and face. To our knowledge, this is the first report of such recruitment patterns during exercise. Results of actual student participation, with organized group discussions, convince us that laboratory teaching remains the premiere mechanism for teaching and learning organ-system physiology.

Animals↗
PubMed2006

Color, reference, and expertise in language acquisition.

In learning the meaning of a new term, children need to fix its reference, learn its conventional meaning, and discover the meanings with which it contrasts. To do this, children must attend to adult speakers--the experts--and to their patterns of use. In the domain of color, children need to identify color terms as such, fix the reference of each one, and learn how each is used in the language. But color is a property, and terms for properties appear to be more difficult to grasp than do those for objects, actions, and relations. Although children find some domains easier to learn than others, they depend in each case on the expertise of adult speakers.

Adult↗
PubMed2000

Different hippocampal activity profiles for PKA and PKC in spatial discrimination learning.

Protein kinases are considered essential for the processing and storage of information in the brain. However, the dynamics of protein kinase activation in the hippocampus during spatial learning are poorly understood. In this study, rats were trained to learn a holeboard spatial discrinmination task and the activity profiles for cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) and Ca2+/ phospholipid-dependent protein kinase C (PKC) in the hippocampus were examined. Hippocampal PKA activity increased rapidly on Day 1 of spatial learning and remained moderately high at later stages of acquisition. In contrast, PKC activity increased in particulate fractions compared with cytosolic fractions after habituation training and was maximal at Day 3 of spatial acquisition. The results establish a temporal dissociation between PKA and PKC during acquisition of spatial discrimination learning.

Animals↗