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At least 433 records · Page 24Linked to original sources
PubMedDate not supplied

Mediodorsal thalamic lesions impair trace eyeblink conditioning in the rabbit.

Rabbits received lesions of the mediodorsal nucleus of the thalamus (MDN) or sham lesions and were subjected to classical eyeblink (EB) and heart rate (HR) conditioning. All animals received trace conditioning, with a.5-sec tone conditioned stimulus, a .5-sec trace period, and a 50-msec periorbital shock unconditioned stimulus. Animals with MDN lesions acquired the EB conditioned response (CR) more slowly than sham-lesioned animals. However, previous studies have shown that MDN damage does not affect delay conditioning using either .5-sec or 1-sec interstimulus intervals. The lesions had no significant effect on the HR CR. These results suggest that information processed by MDN and relayed to the prefrontal cortex is required for somatomotor response selection under nonoptimal learning conditions.

Animals↗
PubMed2001

Modulation of induced gamma band responses and phase synchrony in a paired associate learning task in the human EEG.

It has been proposed that associative learning is accomplished by the formation of cell assemblies and synchronous activity among the neurons of such an assembly. Induced gamma band responses (GBRs) and phase synchrony between electrode sites are discussed as a signature of activity within a cell assembly. To examine the activation of this network due to memory recall, a paired associate learning paradigm was used. EEG was analyzed in the frequency domain. Results showed a significant increase of induced GBRs at posterior and anterior electrode sites in the recall sequence of the learning condition. Furthermore, phase synchrony revealed a broad distribution pattern of phase synchrony between posterior and frontal electrode sites.

Adult↗
PubMed1994

When implicit learning fails: amnesia and the problem of error elimination.

We propose that one of the major functions of explicit memory is the elimination of learning errors. The hypothesis is explored by means of a stem completion task in which subjects are presented with stems having many potential completions, and in the initial phase are either encouraged to guess, the "errorful" procedure, or are provided with the correct completion, the "errorless" condition. Learning is then tested over a sequence of nine trials. The performance of amnesic subjects who are assumed to have good implicit but bad explicit learning is compared with that of normal elderly subjects, who are assumed to have an intermediate level of explicit learning skill, and young controls who are expected to be high in both implicit and explicit learning capacity. As predicted, errorless learning is beneficial, with the effect being particularly marked for the amnesic group. A detailed analysis of the intrusion errors supports an interpretation of the results in terms of the relative contribution to the three groups of implicit learning, which is assumed to be particularly vulnerable to interference. Implications for the analysis of normal learning, and for the rehabilitation of brain damaged patients are discussed.

Adult↗
PubMed2006

[The forming of child and adolescent adaptability].

Adaptability is an ability of the organism to spend its functional reserve in order to keep the balance with the environment and then make up for the use of this reserve. The adaptation of a growing organism to the environment is an intersystem process. The condition of functional intersystem regulation and cardiac rhythm variability in particular, serve as indicators of child adaptability. Adaptability is formed under the influence of such biological factors as heredity, age, gender, health status, and such environmental ones as nutrition balance, quality of life, physical activity, day regimen, and learning conditions. The authors developed a conceptual model of interrelation between biological and environmental factors in the forming of child adaptability.

Adaptation, Physiological↗
PubMed1979

Recognition memory for typical and unusual faces.

In four studies, recognition memory for faces rated as similar to a prototype was found to be inferior to memory for faces rated as unusual in appearance. This result was obtained under both incidental and intentional learning conditions, at presentation rates ranging from 3 to 15 sec, and with retention intervals from 3 to 24 hr. A fifth experiment established interitem similarity as the structural basis of this typicality effect in recognition memory. Difficulties in interpreting the findings in terms of some current models for classification learning, depth of processing models, or present models of the word frequency effect are discussed.

Attention↗
PubMed1997

Dental anxiety among adolescents in St. Petersburg, Russia.

This small-size epidemiologic investigation examined the prevalence and etiology of dental fear and anxiety among 288 schoolchildren aged 13-18 years in St. Petersburg, Russia. The adolescent population was collected from a larger sociological investigation performed in Russia during the early period of reforms. The investigation revealed a comparatively elevated anxiety level with an average DAS score of 10.0 and a prevalence of high dental fear of 12.6%. The present study showed that the origin of dental anxiety as reported by adolescent, urban Russians parallels much of previous results from the US and Western Europe. Thus, the etiology of dental anxiety was related to negative dental experiences and this conditional learning seemed to be especially prevalent in the presence of previous oral pain experiences and an existing dental anxiety in the family.

Adolescent↗
PubMed1993

[The significance of context for episodic memory in young and elderly people].

In gerontological memory research it is generally thought that the decline in episodic memory performance observed in elderly adults is caused by deficits in contextual processing. This hypothesis is based on the assumptions of the levels-of-processing model, which suggest that memory performance is enhanced if the context is considered during learning. According to the model, integrating the context with an event is an effortful and age-sensitive process. 36 younger (M = 26.98 years) and 36 older (M = 68.60 years) adults learned three lists of words. Half of the words in each list were presented with a context word belonging to the same conceptual category as the target. Each list was tested by different memory tasks (e.g., lexical decisions, free recall). The context was encoded either incidentally or intentionally. The processing of context facilitated free recall in both age groups and in both learning conditions. The results contradict the assumption that the integration of an event with its context is an effortful process that declines with age.

Adolescent↗
PubMed1994

Acquisition of new concepts by two amnesic patients.

Two Korsakoff amnesics (A.G. and G.S.) and two control subjects were taught six new concepts. Each concept was composed of three parts: the name of the concept, the context in which the concept originated and its definition. The learning procedure consisted of two phases: (1) learning the concept names and definitions by means of the vanishing-cues method; (2) practice on examples of the concepts through a classification task: examples were either set in the same context as that given in the original definition or in mixed contexts (same and new contexts). Subjects were then tested after 24 hours, a week and a month on their ability to identify new examples as belonging to one of the conceptual rules studied (transfer tests). Both patients showed substantial learning. Patient A.G. was slow and dependent of the first letter cues in the vanishing-cues learning phase but nevertheless, she acquired a large and flexible conceptual knowledge and this was especially true for concepts that were practised by means of mixed-context examples. Patient G.S. easily learned to associate the definitions with the concept names but her conceptual knowledge remained more limited. These results confirm the existence of a semantic learning ability in amnesic patients. They also suggest that under appropriate learning conditions, amnesics may eventually acquire a new flexible conceptual knowledge.

Alcohol Amnestic Disorder↗
PubMed1997

Lesions of the mediodorsal nucleus of the thalamus and classical eyeblink conditioning under less-than-optimal stimulus conditions: role of partial reinforcement and interstimulus interval.

Rabbits received lesions of the mediodorsal nucleus of the thalamus (MD) or sham lesions and were subjected to classical eyeblink (EB) and heart rate (HR) conditioning. Separate groups of sham and lesioned animals received either 50% or 25% reinforcement with a periorbital shock unconditioned stimulus. Other groups received an interstimulus interval of either 1.0 or 1.5 s. Animals with MD lesions acquired the EB conditioned response (CR) more slowly than sham-lesioned animals with either the 1.5-s ISI or with the 25% reinforcement schedule. The lesions had no significant effect on the HR CR, however. Results suggest that information processed by MD is relayed to the prefrontal cortex and is required for somatomotor response selection under nonoptimal learning conditions.

Animals↗
PubMedDate not supplied

Pavlovian conditioning and rule learning.

The experiment reviewed here was an attempt to show that two differential Pavlovian conditioning designs, namely positive and negative patterning, can best be understood as rule learning. First, it is shown that positive patterning is equivalent to the logical rule of conjunction (AND) and that negative patterning is equivalent to the logical rule of exclusive disjunction (XOR). It is assumed that in order to learn both kinds of discrimination subjects learn to use the according rule. If this is the case, the observed differentiation should be independent of the number of reinforcements for each individual stimulus. Second, subjects should be able to transfer the rule to new stimuli. Forty human subjects were randomly divided into four groups (N = 10 each). Two factors were manipulated independently between subjects: (1) positive vs negative patterning, and (2) 2 vs 4 pairs of trained stimuli. Second interval skin conductance responses were measured. During initial acquisition positive as well as negative patterning occurred independently of number of pairs of trained stimuli (with total amount of training kept constant). Furthermore, AND as well as XOR could be transferred to new stimuli.

Adult↗
PubMed1989

The generation effect extended: memory enhancement for generation cues.

The generation effect is the greater memorability of a response that is actively produced (e.g., in answering a question from memory) than one that is more passively produced (as in reading the answer). The present three experiments addressed a question that is critical to the theoretical interpretation of the generation effect: Is memory enhanced for the cues that are used to elicit generated responses? Using incidental learning procedures, Experiments 1 and 2 gave an affirmative answer (although the effect was substantially weaker than the generation effect for responses). Enhancement of memory for generation cues was observed both in a within-subject/within-list design (reading and generation items within the same trial blocks; Experiment 1) and in a between-subjects design (reading and generation tasks for different groups of subjects; Experiment 2). In Experiment 3, memory enhancement for generation cues was used to produce a previously unobtained result--a generation effect for nonsense responses under incidental learning conditions. These findings provide critical evidence required by theories that interpret the generation effect in terms of enhanced processing of the cue-response item.

Cues↗
PubMed2006

Classical conditioning and expectancy in placebo hypoalgesia: a randomized controlled study in patients with atopic dermatitis and persons with healthy skin.

The effectiveness of placebos is unchallenged. However, it is still not clear on which mechanisms the placebo effect is based. Besides expectancy theories, classical conditioning is discussed as a major explanatory model. In an experimental conditioning design we tested 96 participants, 48 with atopic dermatitis (24 male, 24 female) and 48 with healthy skin (24 male and 24 female). All of them received a neutral ointment with a different briefing ("pain-reducing ointment" versus "neutral ointment"). Electrical pain stimuli were subsequently applied, which selectively induce a painful sensation. In the case of the learning condition (classical conditioning) and unbeknown to the participants, the intensity of the pain stimulus was reduced by 50% after the ointment had been applied. The study addressed the question whether the pain experienced by the patients with atopic dermatitis could be reduced through a placebo effect and whether the placebo effect was achieved through expectancy or through a process of classical conditioning or both. The results indicate that a placebo effect is achieved via expectancy and classical conditioning. However, conditioning processes seem to be necessary for a longer lasting effect. The extent of this effect seemed to be greater in atopics than in healthy controls. Expectancy, achieved through verbal instruction, might also be seen as a conditioned stimulus that reactivates earlier stimulus associations.

Adolescent↗
PubMed2004

Distance cognition in virtual environmental space: further investigations to clarify the route-angularity effect.

Two experiments with 72 participants in total investigated the route-angularity effect. This effect is shown when a greater number of turns along a route increase the estimated length of this route. In this study it was shown that the route-angularity effect is likely to be a memory-based effect depending on task difficulty. The important factor seems to be how heavily memory is loaded during learning. The route-angularity effect even appears in intentional learning, when memory is loaded heavily. Under this learning condition participants know beforehand that they have to estimate distances. All experiments were conducted in a controlled virtual environment, which allows a reliable investigation of distance estimations in environmental space.

Adult↗
PubMed1999

Verbal memory in non-demented patients with idiopathic Parkinson's disease.

This study assessed the verbal memory functions of 20 patients with idiopathic Parkinson's Disease (PD) without any clinical evidence of dementia and 20 Medical Control (MC) patients with similar levels of physical disability. Performance was compared on tests of immediate recall, word list learning in intentional and incidental contexts, word completion priming, remote memory, metamemory and awareness of mnestic abilities. Significant differences were found in new learning of verbal material under incidental but not intentional learning conditions. Group differences were also observed on measures of remote memory and metamemory. The groups did not differ in word completion priming performance or recognition memory. These findings are consistent with other evidence suggesting that PD patients without dementia may have subtle cognitive deficits that affect memory performance. These may be attributable to impairments of attention allocation, formulation of retrieval strategies, and effortful learning associated with frontal lobe dysfunction. The group differences could not be attributed to impairments of intellectual functions, verbal fluency, level of physical disability, or mood disturbance.

Aged↗
PubMed2001

Simultaneous learning of different regularities in sequence learning tasks: limits and characteristics.

Two experiments are reported which were designed to investigate the generality and the power of the mechanisms underlying sequence learning. In both experiments, participants reacted to systematic sequences of tones. They were informed that there was a tone systematicity. Participants were not told that the interval between a response to a tone and the onset of the subsequent tone (response-signal interval, RSI) also varied according to a fixed regularity. Experiment 1 showed that the unattended RSIs were learned when they were uniquely related to the tone sequence, but not when the relation was ambiguous. Experiment 2 showed that, on the basis of the traditional reaction time performance measure, participants who learned the RSIs by attending to their systematicity could not be distinguished from those in an incidental learning condition in which the RSI systematicity was unattended. However, a model-based analysis of the processes contributing to judgements about the event sequences suggested that the two groups had acquired qualitatively different knowledge.

Adult↗
PubMed1975

Impacts of environmental stress exposure on central nervous functional patterns. A quantitative approach to evoked potential data.

Albino rats and rhesus monkeys with chronically implanted electrodes in cortical and subcortical, vasomotory and emotionally relevant brain regions were subjected to psycho-nerval stress (short-term stressful CR learning experiments on rats, long-term environmental stress with disturbances of the diurnal rhythm and social hierarchy on rhesus monkeys). Applying average computer techniques and discriminance analyses to evoked potentials (average evoked potentials = AEP to standardized optic-acoustic test stimuli) we were able to objectify the effect of different stress categories on central nervous functional patterns. These phenomena of electrical activity of the CNS proved to be extremely responsive to the stress exposure (avoidance conditioned learning experiments or socio-emotional overstrain). Under moderated stress (CR phases of acquisition and stabilization), time-space patterns of a primary facilitation of AEP could be established, expressing an improved energetic capacity of the CNS (adaptive effect). On the other hand, there was a generalized impairment of bioelectric information processing in temporal correlation with an increase in psycho-nervous stress exposure to rats (CR phases of differentiation). During long-term socio-emotional stress exposure of rhesus monkeys the highly significant changes of AEP-patterns (increasing fall short of the set point of the bioelectric level of activity with segmental differences in the multiphasic evoked potential) are to be interpreted as maladaptive processes in central nervous function under long lasting high stress conditions.

Adaptation, Physiological↗
PubMed1986

Electrophysiological evidence for right frontal lobe dominance in spatial visuomotor learning.

Slow negative potential shifts were recorded together with the error made in motor performance when two different groups of 14 students tracked visual stimuli with their right hand. Various visuomotor tasks were compared. A tracking task (T) in which subjects had to track the stimulus directly, showed no decrease of error in motor performance during the experiment. In a distorted tracking task (DT) a continuous horizontal distortion of the visual feedback had to be compensated. The additional demands of this task required visuomotor learning. Another learning condition was a mirrored-tracking task (horizontally inverted tracking, hIT), i.e. an elementary function, such as the concept of changing left and right was interposed between perception and action. In addition, subjects performed a no-tracking control task (NT) in which they started the visual stimulus without tracking it. A slow negative potential shift was associated with the visuomotor performance (TP: tracking potential). In the learning tasks (DT and hIT) this negativity was significantly enhanced over the anterior midline and in hIT frontally and precentrally over both hemispheres. Comparing hIT and T for every subject, the enhancement of the tracking potential in hIT was correlated with the success in motor learning in frontomedial and bilaterally in frontolateral recordings (r = 0.81-0.88). However, comparing DT and T, such a correlation was only found in frontomedial and right frontolateral electrodes (r = 0.5-0.61), but not at the left frontolateral electrode. These experiments are consistent with previous findings and give further neurophysiological evidence for frontal lobe activity in visuomotor learning. The hemispherical asymmetry is discussed in respect to hemispherical specialization (right frontal lobe dominance in spatial visuomotor learning).

Contingent Negative Variation↗