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PubMedDate not supplied

Recent learned helplessness/irrelevance research in Japan: conceptual framework and some experiments on learned irrelevance.

In Section 1, a conceptual framework within which to study learned helplessness (LH), learned irrelevance (LI) and the related phenomena is introduced. In Section 2, three rat experiments on LI conducted in our laboratory using a conditioned suppression of licking preparation are introduced. In Experiment 1, the phenomena of LI and general LI were confirmed. In Experiment 2, random presentations of CST/US were found to interfere with subsequent initial excitatory conditioning to CSL under random CSL/US presentations. In Experiment 3, pre-paired presentations of CSN or CST with US before random CST/US presentations was found to have an attenuating effect on the development of general LI.

Animals↗
PubMed1986

In vivo modulation of brain cholesterol level and learning performance by a novel plant lipid: indications for interactions between hippocampal-cortical cholesterol and learning.

In this account we report in vivo effects of a plant lipid preparation (MMPL) on brain cholesterol and the activity and learning performance of aging male rats. Three-month-old rats were fed for 3 months with a diet that was enriched with 3% MMPL. Another group of 18 month-old rats was fed for 6 months with a 3% MMPL-enriched diet. This food regime lowered markedly the cholesterol level in the hippocampal and cortical regions and increased their lipid membrane fluidity. The animals of both age groups also responded to MMPL with a higher activity and their learning performances, compared to normal diet-fed animals, improved notably. This improvement continued at least 4 months after terminating the supply of MMPL. Significant inverse correlationships were obtained between the length of the training period required to attain proper criteria and cholesterol levels of the hippocampal and cortical brain fractions.

Activity Cycles↗
PubMed1995

Perceptual learning in vernier acuity: what is learned?

It has been suggested that the improvement of vernier acuity in the course of practice reflects "fine tuning" of the visual mechanisms underlying vernier acuity. Masking studies suggest that an important source of information by which the visual system may accomplish fine vernier acuity is the activity in orientation tuned channels. Therefore, we investigated whether improvement in vernier acuity after training was accompanied by systematic changes in the orientation tuning characteristics of vernier acuity (as revealed by simultaneous spatial noise masking). The results show large interindividual variation in learning vernier acuity. However, they reveal a close correspondence between the improvement in vernier acuity and the narrowing of the orientation tuning function. Thus, the results provide some support for the notion of narrowing of the orientation characteristics of vernier acuity in the course of learning.

Humans↗
PubMed1995

Learning to ignore: psychophysics and computational modeling of fast learning of direction in noisy motion stimuli.

The effects of practice on the discrimination of direction of motion in briefly presented noisy dynamic random dot patterns are investigated in several forced-choice psychophysical tasks. We found that the percentage of correct responses on any specific task increases linearly with repetition of trials within roughly 200 trials from about chance to a performance of 90% or better. The level of performance remained constant or improved over several days, and in most instances it did not transfer when stimulus parameters changed. We used a modified Radial Basis Function (RBF) representation to model the psychophysical tasks. The performance of the model is functionally similar to the psychophysical results. We propose a Hebbian learning algorithm which deactivates the inputs from neurons responding to motion noise in the stimulus. Our computational model suggests that to solve this task in biological systems, neurons (perhaps in MT) improve their performance by 'learning to ignore' noise in the image.

Acoustic Stimulation↗
PubMed2006

Retrosplenial cortex lesions impair water maze strategies learning or spatial place learning depending on prior experience of the rat.

There has been debate whether lesions strictly limited to retrosplenial (RS) cortex impair spatial navigation, and how robust and reliable any such impairment is. The present study used a detailed behavioral analysis with naive or strategies-pretrained rats given RS lesions and trained in a water maze (WM). Naive RS lesioned rats failed to acquire the required WM strategies throughout training. Strategies-pretrained RS lesioned rats were specifically impaired in spatial place memory without a WM strategies impairment. Additional training overcame the spatial memory impairment. Thus the behavioral consequences of the lesion depend on the specific previous experience of the animal. The use of appropriate training and testing techniques has revealed experience-dependant dissociable impairments in WM strategies learning and in spatial memory, indicating that RS cortex is involved in both forms of learning.

Animals↗
PubMed2005

Post-training intra-amygdala amphetamine injections given during acquisition of a stimulus-response (S-R) habit task enhance the expression of stimulus-reward learning: further evidence for incidental amygdala learning.

The effect of post-training intra-amygdala amphetamine injections was examined on the acquisition and expression of a visual discrimination task. Rats were trained to enter four lit arms for food (stimulus-response) and avoid unlit arms on an eight-arm radial maze visual discrimination task. Post-training intra-amygdala amphetamine injections (10 microg) were given for 4 consecutive days during the mid-point of training (days 20-23). The number of lit arm entries was used as a measure of stimulus-response habit learning 24 h after each injection. Twenty-four hours after the last injection, a transfer test was run to assess the effect of the same post-training manipulation. This transfer test assessed the amount of time spent in the lit arms and was used as a measure of stimulus-reward learning. Compared to saline-injected rats, rats that received post-training amphetamine spent more time in lit as opposed to dark arms during the transfer test. This occurred in the absence of an increase in the number of correct arm entries during visual discrimination training. This suggests that post-training amphetamine strengthened a stimulus-reward association that did not immediately affect behavioral output. This association may reflect a mnemonic representation stored in an ensemble of amygdala neurons.

Amphetamine↗
PubMed2005

Learning-dependent activation of Fra-1: involvement of ventral hippocampus and SNc/VTA complex in learning and habit formation.

Although the effect of overtraining on learning processes in rats has long been studied, only few studies have specifically assessed the differential involvement of brain areas in habit formation. We used the analysis of expression of the immediate early gene Fra-1 as a tool to differentiate the areas involved in training and overtraining. Behavioural experiments showed that instrumental performance (signalled and non-signalled instrumental tasks), but not pavlovian conditioned responses, were no longer under the control of the incentive value of the reward after overtraining. The number of Fra-1 expressing neurons was increased in SNc/VTA and ventral hippocampus after training in all groups independently of behavioural performance. After overtraining, the number of learning-induced Fra-1 immunoreactive neurons remained increased in the SNc/VTA. However, in CA1, it significantly decreased in the signalled instrumental group, whereas it further increased in the pavlovian group, with no modulation in non-signalled instrumental animals. The increase in the number of Fra-1 neurons observed after training in SNc/VTA and ventral hippocampus suggests that a general underlying incentive process regulates Fra-1. Moreover, the sustained increased expression of Fra-1 in the SNc/VTA after instrumental overtraining could reflect a possible role of dopaminergic neurons in habit formation.

Animals↗
PubMed2004

Language learning: how much evidence does a child need in order to learn to speak grammatically?

In order to learn grammar from a finite amount of evidence, children must begin with in-built expectations of what is grammatical. They clearly are not born, however, with fully developed grammars. Thus early language development involves refinement of the grammar hypothesis until a target grammar is learnt. Here we address the question of how much evidence is required for this refinement process, by considering two standard learning algorithms and a third algorithm which is presumably as efficient as a child for some value of its memory capacity. We reformulate this algorithm in the context of Chomsky's 'principles and parameters' and show that it is possible to bound the amount of evidence required to almost certainly speak almost grammatically.

Algorithms↗
PubMed2004

Invertebrate learning: what can't a worm learn?

The nematode worm Caenorhabditis elegans can learn and remember the stimuli it encounters, the environment it is in, and its own physiological state. Analyses of mutations in C. elegans that affect different aspects of experience are beginning to address the nature of learning.

Animals↗
PubMed2006

Paired-associate learning, phoneme awareness, and learning to read.

We report two studies examining the relations among three paired-associate learning (PAL) tasks (visual-visual, verbal-verbal, and visual-verbal), phoneme deletion, and single-word and nonword reading ability. Correlations between the PAL tasks and reading were strongest for the visual-verbal task. Path analyses showed that both phoneme deletion and visual-verbal PAL were unique predictors of a composite measure of single-word reading and of irregular word reading. However, for nonword reading, phoneme deletion was the only unique predictor (and visual-verbal PAL was not a significant predictor). These results are consistent with the view that learning visual (orthography) to phonological mappings is an important skill for developing word recognition skills in reading and that individual differences in this ability can be tapped experimentally by a PAL task.

Awareness↗
PubMed2000

The interaction of observational learning with overt practice: effects on motor skill learning.

This study explored various methods of combining observational learning via demonstration with the effects of overt practice for learning a discrete action pattern. Three groups were compared that varied by the timing of demonstration in relation to practice. An all-pre-practice demonstration group viewed 10 pre-practice videotape demonstrations of an expert performing the skill, and then engaged in practice. An interspersed demonstration group viewed one pre-practice demonstration, then initiated practice on the skill. Every three attempts, practice was halted while participants viewed another demonstration, with this pattern repeated throughout acquisition. A combination demonstration group experienced elements of each schedule by viewing five demonstrations prior to practice, then five more once practice had begun (one every three attempts) so that modeling was completed by mid-acquisition. Ratings of form and accuracy were assessed in an acquisition phase, an immediate retention test, and a 48-h retention test. Group main effects for form scores were detected in acquisition, immediate, and 48-h retention, with the combination group obtaining the highest form scores, followed by the all-pre-practice group, and finally the interspersed group. These findings suggest that several modeling exposures before practice and several more exposures in the early stages of practice were optimal for acquisition and retention of form.

Adult↗
PubMed2002

Visual statistical learning in infancy: evidence for a domain general learning mechanism.

The rapidity with which infants come to understand language and events in their surroundings has prompted speculation concerning innate knowledge structures that guide language acquisition and object knowledge. Recently, however, evidence has emerged that by 8 months, infants can extract statistical patterns in auditory input that are based on transitional probabilities defining the sequencing of the input's components (Science 274 (1996) 1926). This finding suggests powerful learning mechanisms that are functional in infancy, and raises questions about the domain generality of such mechanisms. We habituated 2-, 5-, and 8-month-old infants to sequences of discrete visual stimuli whose ordering followed a statistically predictable pattern. The infants subsequently viewed the familiar pattern alternating with a novel sequence of identical stimulus components, and exhibited significantly greater interest in the novel sequence at all ages. These results provide support for the likelihood of domain general statistical learning in infancy, and imply that mechanisms designed to detect structure inherent in the environment may play an important role in cognitive development.

Age Factors↗
PubMed2004

Avoidance learning in the crayfish (Procambarus clarkii) depends on the predatory imminence of the unconditioned stimulus: a behavior systems approach to learning in invertebrates.

Signaled avoidance learning in crayfish (Procambarus clarkii) was investigated when the crayfish were not confined, by indexing two types of locomotive movement to the escape compartment. Mild shocks, which induced tail flipping in the crayfish, and light illumination were used as unconditioned and conditioned stimuli, respectively. In Experiment 1, two groups of crayfish were trained in a one-way shuttle box. The crayfish in Group Forward were placed in the start compartment facing the escape compartment and they were able to escape/avoid shocks by walking forward, while the crayfish in Group Backward were placed in the compartment facing the opposite direction and they were able to escape by tail flipping. Avoidance learning was achieved only by walking, and not by tail flipping despite the fact that consistent tail flipping allowed the crayfish to avoid shocks. In Experiment 2, the experimental conditions were switched by using the ABA design. In this experiment, we confirmed that avoidance behavior was restricted to walking. These results are readily explained by the behavior systems approach.

Animals↗
PubMed2003

A critical exploration of "Working Together, Learning Together"--does it meet the learning needs of nurses?

Recent government educational initiatives have emphasised the need for lifelong learning to facilitate and equip nurses with the appropriate knowledge and skills to operate in a dynamic healthcare delivery system. In this paper I will critically explore a recent educational framework from an educational ideology and curriculum design perspective. It is recognised that any educational program cannot be devised or constructed in a socio-political vacuum and any developments must acknowledge this influence on the context in which nurse education operates. The framework is debated from an ideological perspective and I surmise that an ideological change from Romanticism to Revisionism will facilitate change in curriculum design that is in keeping with the realties of healthcare needs. The educational initiative is explored from a curriculum design perspective utilising Beattie's Fourfold Model. I further surmise that the educational initiative fails to acknowledge the uniqueness of nursing knowledge and the integral learning processes such as reflection thus marginalising nursing as a profession. In this paper I suggest that any educational initiative must recognise the evolving role of nursing, the profession and the realties of healthcare systems to ensure the present and future workforce is skilled and empowered to aspire to these multifaceted demands.

Curriculum↗
PubMed1995

Learning. A mechanism of learning found?

Synaptic plasticity in the cerebellar cortex is abolished and cerebellum-dependent motor learning is decreased in mice lacking a metabotropic glutamate receptor. Is the receptor involved in learning?

Animals↗
PubMed2000

Serial learning by rhesus monkeys: II. Learning four-item lists by trial and error.

Three rhesus macaque monkeys were trained to produce novel 4-item lists (A-->B-->C-->D) on which all items were displayed from the start of training. Subjects were previously trained to produce 4-item lists by adding one item at a time (A, A-->B, A-->B-->C, and A-->B-->C-->D; lists K. B. Swartz et al., 1991). Those lists could be mastered by responding to each new item last. To learn lists on which all items were displayed from the start of training, subjects had to recall the consequences of errors and correct responses to each item. Errors ended the trial; correct responses to A, B, or C allowed the trial to continue. A correct response to D produced food reward. Although the probability of executing a 4-item list correctly by chance was .04, each subject mastered 4 novel 4-item lists by trial and error. The ability of monkeys to use a trial-and-error strategy to learn novel lists provides a basis for studying the development of serial expertise in animals.

Animals↗
PubMed1990

Hippocampal and prefrontal cortex contributions to learning and memory: analysis of lesion and aging effects on maze learning in rats.

Young adult rats with bilateral lesions to the hippocampus or prefrontal cortex, young operated controls, and normal old rats were tested on two complex mazes in the Hebb-Williams series. Approximately half the animals were previously trained on one of the mazes; the remainder received no previous training. The trained hippocampal rats showed sparing of memory for the general skill of maze learning but poor recall of the specific maze on which they had been previously trained. The opposite pattern was observed in trained prefrontal rats. In contrast, the aged rats' memory for maze-specific and maze-general information was impaired. The results confirmed the importance of the hippocampus for recalling highly specific information and pointed to a possible role for the frontal lobes in learning and remembering nonspecific skill-related information. The generalized deficit of the aged rats indicates that both types of memory were compromised and offers further evidence of frontal lobe and hippocampal dysfunction in normal aging.

Aging↗