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At least 523 records · Page 29Linked to original sources

PubMed2003

The hyperpolarization-activated HCN1 channel is important for motor learning and neuronal integration by cerebellar Purkinje cells.

In contrast to our increasingly detailed understanding of how synaptic plasticity provides a cellular substrate for learning and memory, it is less clear how a neuron's voltage-gated ion channels interact with plastic changes in synaptic strength to influence behavior. We find, using generalized and regional knockout mice, that deletion of the HCN1 channel causes profound motor learning and memory deficits in swimming and rotarod tasks. In cerebellar Purkinje cells, which are a key component of the cerebellar circuit for learning of correctly timed movements, HCN1 mediates an inward current that stabilizes the integrative properties of Purkinje cells and ensures that their input-output function is independent of the previous history of their activity. We suggest that this nonsynaptic integrative function of HCN1 is required for accurate decoding of input patterns and thereby enables synaptic plasticity to appropriately influence the performance of motor activity.

Action Potentials↗

PubMed2006

Neural cell adhesion molecule (NCAM-/-) null mice show impaired sensitization of the startle response.

The neural cell adhesion molecule (NCAM) plays important roles in development of the nervous system and in synaptic plasticity and memory formation in the adult. The present study sought to further investigate the role of NCAM in learning by testing habituation and footshock sensitization learning of the startle response (SR) in NCAM null mutant (NCAM-/-) and wildtype littermate (NCAM+/+) mice. Whereas habituation is a form of non-associative learning, footshock sensitization is induced by rapid contextual fear conditioning. Habituation was tested by repetitive presentation of acoustic and tactile startle stimuli. Although NCAM-/- mice showed differences in sensitivity in both stimulus modalities, habituation learning was intact in NCAM-/- mice, suggesting that NCAM does not play a role in the mechanisms underlying synaptic plasticity in the startle pathway. Footshock sensitization was elicited by presentation of electric footshocks between two series of acoustic stimuli. In contrast to habituation, footshock sensitization learning was attenuated in NCAM-/- mice: the acoustic SR increase after the footshocks was lower in the mutant than in wildtype mice, indicating that NCAM plays an important role in the relevant brain areas, such as amygdala and/or the hippocampus.

Acoustic Stimulation↗

PubMed2005

Time-limited modulation of appetitive Pavlovian memory by D1 and NMDA receptors in the nucleus accumbens.

Recent research has implicated the nucleus accumbens (NAc) in consolidating recently acquired goal-directed appetitive memories, including spatial learning and other instrumental processes. However, an important but unresolved issue is whether this forebrain structure also contributes to the consolidation of fundamental forms of appetitive learning acquired by Pavlovian associative processes. In addition, although dopaminergic and glutamatergic influences in the NAc have been implicated in instrumental learning, it is unclear whether similar mechanisms operate during Pavlovian conditioning. To evaluate these issues, the effects of posttraining intra-NAc infusions of D1, D2, and NMDA receptor antagonists, as well as d-amphetamine, were determined on Pavlovian autoshaping in rats, which assesses learning by discriminated approach behavior to a visual conditioned stimulus predictive of food reward. Intracerebral infusions were given either immediately after each conditioning session to disrupt early memory consolidation or after a delay of 24 h. Findings indicate that immediate, but not delayed, infusions of both D1 (SCH 23390) and NMDA (AP-5) receptor antagonists significantly impair learning on this task. By contrast, amphetamine and the D2 receptor antagonist sulpiride were without significant effect. These findings provide the most direct demonstration to date that D1 and NMDA receptors in the NAc contribute to, and are necessary for, the early consolidation of appetitive Pavlovian learning.

Animals↗

PubMed1985

Introduction: categorization, cleverness and consciousness.

Various recurring themes in the history of the subject are reviewed. In the context of adaptation to a complex environment, one precondition for survival must be a capacity for object identity, which may be the most basic form of categorization. Evidence will be presented that suggests that the capacity is not learned. In considering learned associations among categorized items, a distinction is made between reflexive and reflective processes: that is between those associations in which a cue or signal provides an unambiguous route to the response, no matter how complex that route may be, in contrast to those in which learned information must be ordered and reordered 'in thought'. An example of one experimental approach to the latter is provided. Finally, the problem of conscious awareness is considered in terms of stored categorical knowledge and associations, on the one hand, and a system that monitors them, on the other. Neurological evidence of disconnections between these different levels is reviewed.

Animals↗

PubMedDate not supplied

Recognition memory for complex visual discriminations is influenced by stimulus interference in rodents with perirhinal cortex damage.

Rats with perirhinal cortex (PRC), hippocampal, or sham lesions were trained on a successive discrimination go/no-go task to examine recognition memory for an array of visual objects with varying interference among the objects in the array. Rats were trained to recognize a target array consisting of four particular objects that could be presented in any one of four possible configurations to cover baited food wells. If the four target objects were presented, the rat should displace each object to receive food. However, if a novel object replaced any one or more of the target objects, then the rat should withhold its response. The number of novel objects presented on nonrewarded trials varied from one to four. The fewer the number of novel objects in the array, the more interference the array shared with the target array, therefore increasing task difficulty. An increased number of novel objects should result in less interference with the target array and decreased task difficulty. Although accuracy was slightly lower in rats with hippocampal lesions compared with controls, the learning of the groups was not statistically different. In contrast, rats with PRC lesions were significantly impaired in learning compared with both control and hippocampal-lesioned rats. The results suggest that recognition memory for complex visual discriminations is affected by stimulus interference in rodents with PRC damage.

Animals↗

PubMed1995

Phonological awareness and visual skills in learning to read Chinese and English.

It is well known that phonological awareness is closely related to reading skill in children who are learning to read an alphabetic script such as English. In this study, the relationship between phonological awareness and reading skill was also investigated in children living in Hong Kong and Taiwan who were learning to read Chinese. This is because children from Taiwan learn a phonological script, known as Zhu-Yin-Fu-Hao, before they are taught to read any Chinese characters. In addition, a high proportion of Chinese characters contain a "phonetic" component which might be used by Chinese readers when they are recognising Chinese words. Consequently, the performance of 137 8-year-old primary children from Britain, Hong Kong and Taiwan on tests of phonological awareness, visual skills and reading ability was examined. Although there were significant correlations between Chinese reading and phonological awareness, the results of a series of regression analyses did not support the view that differences in phonological awareness per se are a primary cause of differences in reading ability amongst children learning to read Chinese. In contrast, performance on the phonological awareness tests (rhyme and phoneme detection) was significantly related to the reading ability of British children even after the effects of IQ and vocabulary had been partialled out. The results also showed that a test of visual skills (visual paired associates learning) was significantly related to the reading ability of the children in Hong Kong and Taiwan, but not to the reading of the British children. In addition, the nature of rhyme and phoneme deletion skills differed in children from Britain and Hong Kong. Whereas British children found it more difficult to delete the first phoneme from an initial consonant blend (e.g., deleting /s/ from star) than from a word which contained a single consonant before the vowel (e.g., deleting /s/ from sit), children from Hong Kong showed exactly the opposite pattern. In addition, performance on a phoneme deletion test appeared to be strongly influenced by whether or not the child had learnt an alphabetic script in the language in which they were being tested.

Awareness↗

PubMed1994

The animal model of human amnesia: long-term memory impaired and short-term memory intact.

Normal monkeys and monkeys with lesions of the hippocampal formation and adjacent cortex (the H+ lesion) were trained on the delayed nonmatching to sample (DNMS) task with a delay of 0.5 s between the sample and the choice. The animals with H+ lesions learned the task normally at this short delay and also exhibited the same pattern of response latencies as normal monkeys. This finding contrasts with previous observations that initial learning of the DNMS task with delays of 8-10 s is impaired after H+ lesions. The absence of an impairment at a delay of 0.5 s indicates that the H+ lesion does not affect short-term memory. In contrast, when monkeys with H+ lesions were tested at longer delays (> 30 s), an impairment was observed. This selective impairment occurred when the delays were presented sequentially (from 0.5 s to 10 min) and also when delays were presented in a mixed order (1 s, 1 min, and 10 min). The data indicate that the H+ lesion produces a selective impairment in long-term memory, in the absence of a detectable deficit in short-term memory or perception. Accordingly, the findings confirm the long-standing idea, based primarily on studies of humans, that short-term memory is independent of medial temporal lobe function. The findings thereby establish an important parallel between memory impairment in monkeys and humans and provide additional support for the validity of the animal model of human amnesia in the monkey.

Amnesia↗

PubMed1982

Morphophonemic rule learning in normal and articulation-disordered children.

This study investigated the phonological learning abilities of articulation-disordered children. Eight normally speaking and eight articulation-disordered kindergarten children were taught an artificial morphophonemic rule. The rule required the subjects to extract and organize phonological information by differentiating among the critical features of stop and fricative consonants. A miniature artificial language paradigm was used to teach the rule by auditorily presenting a limited number of examples of the rule and measuring generalization to untaught items. The groups were compared to determine if they differed in rate or accuracy of learning and generalization of the correct response. Individual patterns of learning were also examined. Results revealed essentially no differences in the way the two groups learned the stop class. In contrast, the disordered children incorporated fricatives into the rule more quickly than the normal children did. In addition, there was a trend for the disordered children to respond with more accuracy ad more generalized responses to the fricatives. This trend was unexpected and is discussed in terms of a sensitive period for learning phonological information.

Articulation Disorders↗

PubMed1995

Empirical evidence that the state dependence and drug discrimination paradigms can generate different outcomes.

The study compared the outcomes generated by the State Dependence and Drug Discrimination paradigms with ethanol in the rat. Food-deprived rats learned to complete a fixed-ratio 10 schedule of bar presses for food within 120 s while treated with 320- to 1250-mg/kg doses of ethanol. Subsequent tests of recall of this response with saline failed to generate any evidence that transfer was hampered following the drug-to-saline state change. In contrast, each of 14 rats learned to discriminate 1250 mg/kg ethanol from saline in a Drug Discrimination procedure that also required the animals to press one of two levers for food according to a fixed- ratio 10 schedule. The results offer the first empirical evidence to demonstrate directly that the State Dependence and Drug Discrimination paradigms can generate different outcomes in otherwise identical experimental conditions.

Animals↗

PubMed2003

A statistical basis for speech sound discrimination.

Infants under six months are able to discriminate native and non-native consonant contrasts equally well, but as they learn the phonological systems of their native language, this ability declines. Current explanations of this phenomenon agree that the decline in discrimination ability is linked to the formation of native-language phonemic categories. The goal of this study was to evaluate the role of input statistics in learning these categories: our hypothesis was that relative frequency is a determinant of the relative order in which categories are acquired. English-learning infants of two age groups (6.5 months and 8.5 months) were tested on their ability to discriminate non-native consonant contrasts using the Conditioned Head Turn Procedure. As predicted, older infants were worse in their performance on the more frequent coronal stop contrast than on the less frequent dorsal stop contrast. In contrast, 6.5-month-olds discriminated both contrasts equally well. An adult control group tested with an AX task also discriminated both contrasts equally. These results provide preliminary confirmation of the hypothesis that frequency plays an important role in tuning of phonological systems to properties of the native language. A simple attractor model suffices to account for these and previous results on loss of discrimination of non-native-language contrasts and suggests that the technique of measuring graded loss of multiple contrasts, in combination with observation of input frequencies, can offer a powerful method of assessing infants' phonological representations.

Discrimination Learning↗

PubMed1998

Induction of relational schemas: common processes in reasoning and complex learning.

Five experiments were performed to test whether participants induced a coherent representation of the structure of a task, called a relational schema, from specific instances. Properties of a relational schema include: An explicit symbol for a relation, a binding that preserves the truth of a relation, potential for higher-order relations, omnidirectional access, potential for transfer between isomorphs, and ability to predict unseen items in isomorphic problems. However relational schemas are not necessarily coded in abstract form. Predictions from relational schema theory were contrasted with predictions from configural learning and other nonstructural theories in five experiments in which participants were taught a structure comprised of a set of initial-state,operator-->end-state instances. The initial-state,operator pairs were presented and participants had to predict the correct end-state. Induction of a relational schema was achieved efficiently by adult participants as indicated by ability to predict items of a new isomorphic problem. The relational schemas induced showed the omnidirectional access property, there was efficient transfer to isomorphs, and structural coherence had a powerful effect on learning. The "learning to learn" effect traditionally associated with the learning set literature was observed, and the long-standing enigma of learning set acquisition is explained by a model composed of relational schema induction and structure mapping. Performance was better after reversal of operators than after shift to an alternate structure, even though the latter entailed more overlap with previously learned tasks in terms of the number of configural associations that were preserved. An explanation for the reversal shift phenomenon in terms of induction and mapping of a relational schema is proposed. The five experiments provided evidence supporting predictions from relational schema theory, and no evidence was found for configural or nonstructural learning theories.

Adult↗

PubMed1987

Selective learning impairment of delayed reinforcement autoshaped behavior caused by low doses of trimethyltin.

The organometal neurotoxin trimethyltin (TMT), induces impaired learning and memory for various tasks. However, administration is also associated with other "non-specific" behavioral changes which may be responsible for effects on conditioned behaviors. To determine if TMT treatment causes a specific learning impairment, three experiments were done using variations of a delay of reinforcement autoshaping task in which rats learn to associate the presentation and retraction of a lever with the delivery of a food pellet reinforcer. No significant effects of TMT treatment were found with a short (4 s) delay of reinforcement, indicating that rats were motivated and had the sensorimotor capacity for learning. When the delay was increased to 6 s, 3.0 or 6.0 mg TMT/kg produced dose-related reductions in behaviors directed towards the lever. Performance of a group given 7.5 mg TMT/kg, while still impaired relative to controls, appeared to be better than the performance of groups given lower doses. This paradoxical effect was investigated with a latent inhibition paradigm, in which rats were pre-exposed to the Skinner boxes for several sessions without delivery of food reinforcement. Control rats showed retardation of autoshaping when food reinforcement was subsequently introduced. Rats given 7.5 mg TMT/kg exhibited elevated levels of lever responding during pre-exposure and autoshaping sessions. The results indicate that 7.5 mg TMT/kg produces learning impairments which are confounded by hyperreactivity to the environment and an inability to suppress behavior toward irrelevant stimuli. In contrast, low doses of TMT cause learning impairments which are not confounded by hyperreactivity, and may prove to be useful models for studying specific associational dysfunctions.

Animals↗

PubMed1987

Effects of mailed preoperative instructions on learning and anxiety.

This study sought to contrast mailing a booklet to accomplish preoperative instruction with teaching performed by nurses after hospital admission. Sixty-six patients were studied in a 700-bed medical center and were assigned to three teaching groups and a control group which did not receive teaching. The researcher compared the four groups preoperatively after admission to determine the patients' knowledge and ability to perform surgical exercises, as well as their anxiety levels. Findings were that patients who received a booklet by mail preadmission learned surgical exercises equally well compared to patients taught postadmission, and mastered significantly more exercise behaviors than those receiving no instruction. No statistical difference in anxiety level was found among groups. One may infer that mailing preadmission material should be considered as an effective teaching mode and alternative to postadmission instruction.

Adolescent↗

PubMed1994

Schoolwork, homework, life's work: the experience of students with and without learning disabilities.

Elementary school students were interviewed about schoolwork, homework, and personal learning projects (e.g., learning about astronomy). Four groups of students were distinguished. Those in the first group experienced school knowledge as an integral part of life and inseparable from their personal projects; students in the second group saw such knowledge as necessary for preparing for life, but as less engaging than their personal projects. For those in the third group, schoolwork was an imposition, contrasting sharply with satisfying personal learning projects. Those in the fourth group lacked absorbing personal learning projects and found schoolwork to be an imposition. Students with learning disabilities (more than students without) fell into the last category. Fostering more favorable motivation and voice (ability to articulate purposes and critique schooling) in such students might involve changing their views of school knowledge, helping them find personal identity-building learning projects, and reducing the dichotomy between schoolwork and personal projects.

Child↗

PubMed1987

Autonomy in children's learning: an experimental and individual difference investigation.

Ninety-one fifth-grade children participated in a study that assessed the effects of motivationally relevant conditions and individual differences on emotional experience and performance on a learning task. Two directed-learning conditions, one controlling and one noncontrolling, were contrasted with each other and with a third nondirected, spontaneous-learning context. Both directed sets resulted in greater rote learning compared with the nondirected-learning condition. However, both the nondirected and the noncontrolling directed-learning sets resulted in greater interest and conceptual learning compared with the controlling set, presumably because they were more conducive to autonomy or an internal perceived locus of causality. Furthermore, children in the controlling condition experienced more pressure and evidenced a greater deterioration in rote learning over an 8-(+/- 1) day follow-up. Individual differences in children's autonomy for school-related activities as measured by the Self-Regulation Questionnaire (Connell & Ryan, 1985) also related to outcomes, with more self-determined styles predicting greater conceptual learning. Results are discussed in terms of the role of autonomy in learning and development and the issue of directed versus nondirected learning.

Child↗

PubMed2001

A possible role of the striatum in linear and nonlinear category learning: evidence from patients with Huntington's disease.

Linear and nonlinear categorization rule learning was examined in patients with Huntington's disease (HD) and a group of controls using the perceptual categorization task. Participants learned to categorize simple line stimuli into 1 of 2 categories over 600 trials. In addition to traditional measures of accuracy, quantitative model-based analyses were applied to each participant's data to characterize better the nature of any observed deficits. In the linear rule condition, HD patients displayed an early-training deficit relative to controls, whereas later in training the HD patients were not statistically different from controls. In the nonlinear rule condition, HD patients displayed both an early- and late-training deficit. The quantitative model-based analyses revealed that the HD patients' deficits in the linear condition were due to an impairment in learning the experimenter-defined rule and not in applying a learned rule inconsistently. In the nonlinear condition, in contrast, the HD patients' deficits were due to an impairment in learning the experimenter-defined rule and in applying a learned rule inconsistently. Overall, these results suggest that HD can result in a deficit in learning both linear and nonlinear categorization rules.

Adult↗

PubMed2002

Teaching the /r/-/l/ discrimination to Japanese adults: behavioral and neural aspects.

Several studies have been conducted to address the learning of a nonnative speech contrast in adulthood, using native speakers of Japanese and the English /r/-/l/ contrast. Japanese adults were asked to identify contrasting /r/-/l/ stimuli (e.g., "rock-lock"). An adaptive training regime starting with initially easy stimuli was contrasted with a fixed training regime using difficult stimuli, with some subjects receiving feedback on the correctness of their responses and others receiving no feedback in both conditions. After three and six sessions of training, subjects received tests assessing identification and discrimination of /r/-/l/ stimuli as well as generalization. In all cases except fixed training without feedback, subjects showed clear evidence of learning, and several indicators suggested that training affects speech perception, rather than simply auditory processes. Neuroimaging studies currently underway are examining the neural basis of these findings.

Behavior↗

PubMed2003

Behavioural phenotypes associated with specific genetic disorders: evidence from a population-based study of people with Prader-Willi syndrome.

BACKGROUND: Prader-Willi syndrome (PWS) is a genetic disorder resulting in obesity, short stature, cryptorchidism, learning disabilities (mental retardation) and severe neonatal hypotonia. Associated with the syndrome are a number of behaviours that are sufficiently distinctive that the syndrome is considered to have a specific 'behavioural phenotype'. METHODS: Through multiple sources we attempted to identify all people with PWS living in one region in the U K. This cohort was augmented by people with PWS from other regions, and a contrast group of people with learning disabilities of varied aetiologies. The main carers were interviewed, using structured and semi-structured interview schedules, to establish the presence and severity of specific behaviours, and PWS diagnostic criteria. The intellectual functioning and attainments of all were determined. Blood samples were obtained for genetic diagnosis from all consenting participants. RESULTS: Although excessive eating was recognized as a potentially severe problem in those with PWS, it was almost universally controlled by food restriction, and therefore not seen as a 'problem behaviour'. Those with PWS differed from a learning disabled group of other aetiologies in the prevalence rates of skin picking, temper tantrums, compulsive behaviours and mood fluctuations, and also in the profile of their adaptive behaviours. CONCLUSIONS: The study confirms the distinct behavioural phenotype of PWS. Specific behaviours occurred significantly more frequently in PWS, compared with an age and BMI matched learning disabled comparison group. A factor analysis of the behaviours involved resulted in three factors that we hypothesized to be independent, and to arise from different mechanisms.

Adaptation, Psychological↗