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Results for “CONDITIONED LEARNING”

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PubMed1993

Modification of the responses of hippocampal neurons in the monkey during the learning of a conditional spatial response task.

In order to analyze the function of the hippocampus in learning, the activity of single neurons was recorded while monkeys learned a task of the type known to be impaired by damage to the hippocampus. In the conditional response task, the monkey had to learn to make one response when one stimulus was shown, and a different response when a different stimulus was shown. It had previously been shown that there are neurons in the hippocampal formation that respond in this task, to, for example, a combination of a particular visual stimulus that had been associated in previous learning with a particular behavioral response. In the present study, it was found that during such conditional response learning, the activity of 22% of the neurons in the hippocampus and parahippocampal gyrus with activity specifically related to the task altered their responses so that their activity, which was initially equal to the two new stimuli, became progressively differential to the two stimuli when the monkey learned to make different responses to the two stimuli. These changes occurred for different neurons just before, at, or just after the time when the monkey learned the correct response to make to the stimuli. In addition to these neurons, which had differential responses that were sustained for as long as the recordings continued, another population of neurons (45% of those with activity specifically related to the task) developed differential activity to the two new stimuli, yet showed such differential responses transiently for only a small number of trials at about the time when the monkey learned. These findings are consistent with the hypothesis that some synapses on hippocampal neurons modify during this type of learning so that some neurons come to respond to particular stimulus-response associations that are being learned. Further, the finding that many hippocampal neurons started to reflect the new learning, but then stopped responding differentially (the transient neurons), is consistent with the hypothesis that the hippocampal neurons with large sustained changes in their activity inhibited the transient neurons, which then underwent reverse learning, thus providing a competitive mechanism by which not all neurons are allocated to any one learned association or event.

Action Potentials↗

PubMed2003

Facilitation of conditioned taste aversion learning by systemic amphetamine: role of nucleus accumbens shell dopamine D1 receptors.

The role of dopamine (DA) in associative learning was studied in a conditioned taste aversion (CTA) paradigm with sucrose as the conditioned stimulus (CS) and intraperitoneal lithium chloride as the unconditioned stimulus (US). Drinking on trial of a 15% sucrose solution followed 1 h later by lithium chloride (20 or 40 mg/kg i.p.) resulted in mild CTA, as shown by reduction of drinking of the sucrose solution 24 h later. Amphetamine sulphate (0.125, 0.25, 0.50 and 1.0 mg/kg s.c.), administered on trial 5 min after sucrose drinking, facilitated CTA with maximal effects at 0.25 mg/kg s.c. Amphetamine given in the absence of lithium or 45 min after sucrose did not affect sucrose intake. The DA D1 receptor antagonist SCH 39166, administered before amphetamine either systemically (0.0125 mg/kg s.c.) or in the nucleus accumbens shell (NAc; 0.025 micro g/ micro L on each side) prevented the facilitation of CTA induced by amphetamine. It is concluded that amphetamine facilitates CTA learning by strengthening the consolidation of gustatory short-term memory via D1 receptors of the NAc shell.

Amphetamine↗

PubMed2000

Effects of acute ethanol on indices of cognitive-behavioral performance in rats.

The present experiment examined the effects of ethanol on several complex operant behaviors in rats. Tasks included: temporal response differentiation (TRD) to assess timing behavior; differential reinforcement of low response rates (DRL) to assess timing and response inhibition; incremental repeated acquisition (IRA) to assess learning; conditioned position responding (CPR) to assess auditory, visual, and position discrimination; and progressive ratio (PR) to assess motivation. Ethanol (0.0, 0.5, 1.0, 1.5, 2.0, and 3.0 g/kg via orogastric gavage) reduced accuracy and/or percent task completed for the TRD, DRL, and CPR tasks. For CPR, this reduction was accompanied by a reduction in response rates. Ethanol also reduced response rates on the PR task. There were no effects of ethanol on IRA performance. These data suggest that ethanol can selectively impair performance on cognitive-behavioral tasks and that these effects can occur at doses that do not affect the subjects' ability to respond.

Alcohol Drinking↗

PubMed1998

Integrating learning contexts in a medical informatics program--preparing for the introduction of PACS.

This paper analyzes the possibilities to extend learning contexts within a one-year medical informatics educational program (MIP) at a Radiology Department in Sweden. The MIP was carried out within a theoretical framework based upon the integration of four learning contexts, which were inspired by Nonaka's theory of organizational knowledge creation. A summary of organizational knowledge creation theory and the ideas behind the learning contexts are presented. The main objective of the study was to investigate what would be the major benefits from the use of various learning contexts in a one-year medical informatics program? The MIP was found to form a basis for better learning conditions by increasing the flexibility, accommodating greater numbers of students as well as offering better possibilities for continuous learning. Evaluation of the MIP revealed that 98% of radiology department staff as compared to 39% of the intensive care unit staff, who had followed the hospital routine program, felt competent enough to independently use the functions of a new medical system. Although there are good reason to believe that the superior confidence for information technology (IT) is due to the integration of learning contexts, it can not be excluded that it may be due to other reasons also.

Education, Medical, Continuing↗

PubMed1999

Presupplementary motor area activation during sequence learning reflects visuo-motor association.

In preceding studies (Hikosaka et al., 1996; Sakai et al., 1998) we have shown that the presupplementary motor area (pre-SMA), an anterior part of the medial premotor cortex, is active during visuo-motor sequence learning. However, the paradigm required the subjects first to acquire correct visuo-motor association and then to acquire correct sequence, and it was still unknown which of the two processes the pre-SMA is involved in. To further characterize the role of pre-SMA, we have conducted another series of functional magnetic resonance imaging experiments using three learning paradigms. The three were the same in that they involved a visuo-motor association component, but they differed in terms of the involvement of sequential components; one involved no sequence learning, whereas the other two involved learning of motor sequence or perceptual sequence. Comparison of the learning conditions with the any-order button press condition revealed pre-SMA activation in all three paradigms. The pre-SMA activation remained unchanged during learning of visuo-motor associations but decreased during learning of sequences, suggesting that the pre-SMA is related to visuo-motor association rather than sequence. The decrease of pre-SMA activation in the sequential paradigms may reflect the process by which individual visuo-motor associations were replaced by the formation of sequential procedural memory, which occurs outside the pre-SMA. Thus activation of the pre-SMA was related to the extent to which the task performance depended on conscious visuo-motor associations.

Adult↗

PubMed2004

Exposure to hypomagnetic field space for multiple generations causes amnesia in Drosophila melanogaster.

This is the introduction of Drosophila into the study of learning and memory affected by removal of the geomagnetic field (GMF) for successive generations. Using the operant visual learning/memory paradigm at a flight simulator, the present study revealed that wild-type flies raised in a hypomagnetic field environment continuously for 10 successive generations were gradually impaired in visual conditioning learning and memory formation and finally the 10th generation flies became morphs of nonlearners and completely amnesiac. The control experiments show that the impairment could not be ascribed to any apparent sensorimotor problems in Drosophila. The reverse shift from hypomagnetic field (HMF) to natural GMF restored the GMF-free induced amnesia fully after six consecutive generations. Thus, our findings demonstrate conclusively that some serious, but reversible learning and memory impairment may occur for living organisms in a prolonged separation from GMF over many consecutive generations. And Drosophila has the potential to develop into a new model organism for the study of the neurobiology of magnetism for multiple generations.

Amnesia↗

PubMed1993

Incidental and intentional recall in Parkinson's disease: an account based on diminished attentional resources.

The recall of common objects and their spatial location was examined in 65 patients with Parkinson's disease (PD) under conditions in which available attentional resources were manipulated by secondary task demands. PD patients were impaired at item recall particularly under intentional learning conditions but were unimpaired at recall of spatial location. These findings were similar in newly diagnosed, untreated cases as well as patients who had suffered with the disease for an average of 9.6 years. Test performance was not improved by levodopa therapy, despite it benefiting motor control, and was not impaired by anticholinergic medication. Item recall correlated significantly with other memory measures (particularly tasks of working memory) but only weakly with indices of physical disability and traditional frontal-lobe measures. Spatial recall, by contrast, correlated with memory quotient but no other cognitive measure and depression and disease duration failed to correlate significantly with performance on either recall task. These results are attributed to a deficit in attentional resources in PD that impairs performance most markedly for tasks and conditions that make the greatest demands upon effort.

Adult↗

PubMed1997

Epilepsy or stereotypy? Diagnostic issues in learning disabilities.

Approximately 0.8% of people in the general population have epilepsy. Within this group are specific sub-populations who co-present with other additional conditions, learning disability being one such example. Epilepsy rates are the highest of all in this subgroup, between 21% and 50% and positively correlated with degree of learning disability. In addition, in the more severe categories, problems frequently arise when attempting to differentiate epileptic events from other phenomenon, such as stereotyped behaviours and involuntary movements. The individual is unable to communicate changes in consciousness and perception and observers often find it difficult to detect such changes, particularly with regard to the partial epilepsies. Intensive monitoring using EEG and video equipment can often prove valuable in such a situation in assisting carers to recognize epileptic episodes and respond accordingly.

Adult↗

PubMed2002

Crossed unilateral lesions of temporal lobe structures and cholinergic cell bodies impair visual conditional and object discrimination learning in monkeys.

Monkeys with excitotoxic lesions of the CA1/subiculum region in the right hemisphere and with immunotoxic lesions of the cholinergic cells of the diagonal band in the left hemisphere were impaired on a visual conditional task. In this task, correct choice of one of two objects depends on which of two background fields both objects are presented against, irrespective of the spatial positions of the objects. They were not impaired on simple object or shape discrimination tasks. The pattern of impairments is the same as that seen after bilateral excitotoxic lesions of CA1/subiculum, implying that the diagonal band lesion disables the ipsilateral CA1/subiculum. It also argues that CA1/subiculum, sustained by its cholinergic input, is necessary for some forms of nonspatial conditional learning. Addition of an inferotemporal (IT) cortical ablation to the left hemisphere did not affect simple visual discrimination learning, although all the monkeys then failed to learn a new visual conditional task. This demonstrates that intact IT cortex in only one hemisphere is sufficient to sustain simple visual discrimination learning but implies that the cholinergic input and the inferotemporal cortical input to the hippocampus both contribute to visual conditional learning. The subsequent addition of an immunotoxic lesion of the basal nucleus of Meynert in the right hemisphere resulted in an additional impairment on a difficult shape discrimination. This argues that it is the cholinergic projection to the inferotemporal cortex, rather than to the rest of the cortex, which contributes to visual discrimination learning and memory.

Animals↗

PubMed2005

Medical students' mindset for reflective learning: a revalidation study of the reflection-in-learning scale.

The aims of this paper are to examine the measurement properties of the Reflection-in-Learning Scale (RLS) and to identify whether there are relationships between RLS scores early in the medical program and outcomes of the students' academic activity later on. The 14-item RLS was administered to second-year students (N = 275) at start and at end of the third semester, after the students had reviewed their previous learning experience with the Course Valuing Inventory. The internal consistency, temporal stability and dimensionality of the RLS scores were investigated in relation to the start-end perspectives. Furthermore, a 2-year follow-up allowed the assessment of the relationships of third-term RLS scores with sixth-term measures of both academic achievement and diagnostic reasoning as appraised by the Diagnostic Thinking Inventory (DTI). Findings indicate that RLS data have acceptable unidimensionality and consistency of measurement, notwithstanding a significant individual-context interaction. Repeated measures revealed distinct patterns of RLS scores relating to perceived self-efficacy on the ability to reflect. Third-term RLS scores were significant, albeit weak, predictors of sixth-term cognitive achievement and DTI-related diagnostic reasoning ability. In conclusion, the results do not support a major explanatory role for RLS on knowledge representation. Nevertheless, the findings appear to substantiate the construct validity of this tool as an index of the students' frame of mind as regards reflective learning. They suggest that the RLS captures a self-regulation or cognitive housekeeping dimension of the students' reflective learning. The individual pattern of such (reflective) activity is likely to vary with specific learning conditions.

Adolescent↗

PubMed1989

Effects of conditioned stimulus fear-relevance and preexposure on expectancy and electrodermal measures of human Pavlovian conditioning.

The present research investigated the effects of fear-relevance of the conditioned stimulus (CS) and CS preexposure on human electrodermal conditioning and on a continuous measure of expectancy of the unconditioned stimulus (US). Both experiments employed 20 preexposure, 8 acquisition, and 8 extinction trials in a differential Pavlovian conditioning paradigm with shock as the US. In Experiment 1 (N = 48), electrodermal conditioning was retarded by CS preexposure, but was not influenced by fear-relevance of the CS. Expectancy of the US was retarded by preexposure only in the fear-relevant condition. In Experiment 2 (N = 48), the CS/US contingencies was embedded in a visual masking task. Preexposure retarded both electrodermal conditioning and US expectancy. Neither measure was influenced by fear-relevance of the CS. However, fewer subjects in the preexposure condition learned the CS/US relationship and those who did, did so on later trial than those in the no-preexposure condition. Thus, the results indicated clear retardation of conditioning as a result of preexposure, but no reliable effect of fear-relevance.

Adolescent↗

PubMed1999

Cerebellar cortex lesions prevent acquisition of conditioned eyelid responses.

We have used aspiration and electrolytic lesions to investigate the contributions of cerebellar cortex to the acquisition and expression of conditioned eyelid responses. We show that lesions of the anterior lobe of rabbit cerebellar cortex disrupt the timing of previously learned conditioned eyelid responses. These short-latency responses were used as an indication that the cerebellar cortex was sufficiently damaged and that the underlying pathways necessary for the expression of responses were sufficiently intact to support responses. Rabbits were subsequently trained for 15 daily sessions using a new conditioned stimulus. Whereas rabbits in which lesions had no significant effect on response timing showed rapid acquisition of appropriately timed eyelid responses to the new conditioned stimulus, animals with lesions that disrupt timing showed no significant increases in either amplitude or probability of responses. Histological analysis suggests that damage to the anterior lobe of the cerebellar cortex is necessary and sufficient to abolish timing and prevent acquisition. These data indicate that the cerebellar cortex is necessary for the acquisition of conditioned eyelid responses and are consistent with the hypotheses that (1) eyelid conditioning results in plasticity in both the anterior lobe of the cerebellar cortex and in the anterior interpositus nucleus and (2) induction of plasticity in the interpositus requires intact input from the cerebellar cortex.

Animals↗

PubMed2006

The parasitic mite Varroa destructor affects non-associative learning in honey bee foragers, Apis mellifera L.

The parasitic mite Varroa destructor influences flight behavior, orientation and returning success of forager honeybees (Apis mellifera) infested as adults. As impaired orientation toward the nest entrance might be due to deficiency in recognition and responsiveness to stimuli in the environment, we examined effects of V. destructor on sensory responsiveness, non-associative and associative learning of honey bee foragers by using proboscis extension reaction paradigm (PER). Although infested and uninfested workers were initially equally responsive to different concentrations of sugar water, we found differences in non-associative learning. In habituation, PER to repeated sugar stimulation of the antennae occurred faster in infested foragers compared to uninfested foragers. In sensitization, infested foragers showed a lower response to an odor stimulus following sugar stimulation than non-infested foragers. Differences in non-associative paradigms were more pronounced in bees with lower responsiveness to sucrose. In conditioning learning experiments, a significant reduction in proboscis extension response was found 1 min but not 12 min after a single conditioning trial indicating that V. destructor predominantly affects the non-associative components of learning and its underlying neural and molecular processes.

Animals↗

PubMed2005

Regional- and age-dependent reduction in trkB receptor expression in the hippocampus is associated with altered spine morphologies.

BACKGROUND: Changes in densities and in the morphology of dendritic spines in the hippocampus are linked to hippocampal long-term potentiation (LTP), spatial learning, and depression. Decreased brain-derived neurotrophic factor (BDNF) levels seem to contribute to depression. Through its receptor trkB, BDNF is also involved in hippocampal LTP and hippocampus-dependent learning. Conditionally gene-targeted mice in which the ablation of trkB is restricted to the forebrain and occurs only during postnatal development display impaired learning and LTP. METHODS: To examine whether there is a link among impaired hippocampal synaptic plasticity, altered spines, and trkB receptors, we performed a quantitative analysis of spine densities and spine length in the hippocampal area CA1 and the dentate gyrus in conditional mutant mice (trkB(lox/lox)CaMKII-CRE mice). TrkB protein and mRNA levels were assayed using Western blot and in situ hybridization analysis. RESULTS: Fifteen-week-old mutant mice exhibit specific reductions in spine densities and a significant increase in spine length of apical and basal dendrites in area CA1. These alterations correlate with a time- and region-specific reduction in full-length trkB mRNA in the hippocampus. CONCLUSIONS: TrkB functions in structural remodeling of hippocampal dendritic spines, which in turn may affect synaptic transmission and plasticity.

Age Factors↗

PubMed1994

[Discrete dynamic systems: the effect of perceptual structuring on composition and transfer of knowledge about operating sequences].

This paper reports two experiments in which we explored the impact of perceptual grouping of elements on the organization and use of knowledge about how to operate a device. Experiment 1 explored the effects of different perceptual display regions on the creation of chunks when sequences of inputs had to be reproduced. The effects of regions were not homogeneous, but rather their influence depended on interactions between different modalities and learning conditions. Experiment 2 investigated the influence of grouping-induced composition of knowledge elements on the transfer of sequential knowledge. Two different learning criteria were used in the acquisition phase to manipulate the degree of composition of knowledge elements. In the transfer phase, subjects could transfer (1) the whole sequence of one region, (2) two partial sequences of adjacent regions, or (3) single components. It was found that regional invariance and immediate succession of components were both important for transfer performance. These results suggests that the temporal order of regions is important for the organization and use of sequential knowledge, and not the grouping of elements by itself.

Adult↗

PubMed2003

Amygdala modulation of parahippocampal and frontal regions during emotionally influenced memory storage.

Considerable evidence from both animal and human subject research supports the hypothesis that the amygdala, when activated by emotional arousal, modulates memory storage processes in other brain regions. By this hypothesis, changes in the functional interactions of the amygdala with other brain regions during emotional conditions should underlie, at least in part, enhanced memory for emotional material. Here we examined the influence of the human amygdala on other brain regions under emotional and nonemotional learning conditions using structural equation modeling (SEqM). Eleven male subjects received two PET scans for regional cerebral glucose metabolism-one scan while viewing a series of emotionally provocative (negative) film clips and a second scan while viewing a series of more emotionally neutral film clips. Enhanced activity in the right amygdala was related to enhanced memory for the emotional films. To identify potential candidate voxels for SEqM, the functional connectivity of the maximally activated voxel within the right amygdala was investigated using partial least squares. A subset of regions identified by this analysis showing differences functional connectivity with the amygdala between the emotional versus neutral film conditions were then submitted to SEqM, which revealed significantly increased amygdala influences on the ipsilateral parahippocampal gyrus and ventrolateral prefrontal cortex during the emotional relative to the neutral film viewing condition. These findings support the view that increased influences from the amygdala, presumably reflecting its memory-modulation function, occur during emotionally arousing learning situations.

Adult↗

PubMed2006

Conditional visuo-motor learning and dimension reduction.

Conditional visuo-motor learning consists in learning by trial and error to associate visual cues with correct motor responses, that have no direct link. Converging evidence supports the role of a large brain network in this type of learning, including the prefrontal and the premotor cortex, the basal ganglia BG and the hippocampus. In this paper we focus on the role of a major structure of the BG, the striatum. We first present behavioral results and electrophysiological data recorded from this structure in monkeys engaged in learning new visuo-motor associations. Visual stimuli were presented on a video screen and the animals had to learn, by trial and error, to select the correct movement of a joystick, in order to receive a liquid reward. Behavioral results revealed that the monkeys used a sequential strategy, whereby they learned the associations one by one although they were presented randomly. Human subjects, tested on the same task, also used a sequential strategy. Neuronal recordings in monkeys revealed learning-related modulations of neural activity in the striatum. We then present a mathematical model inspired by viability theory developed to implement the use of strategies during learning. This model complements existing models of the BG based on reinforcement learning RL, which do not take into account the use of strategies to reduce the dimension of the learning space.

Basal Ganglia↗

PubMed1995

Impact of time delay, observational learning, and attentional cuing upon word recognition during integrated small-group instruction.

The effects of constant time delay, observational learning opportunities, and differential attentional cuing were examined during the small-group instruction of students in an integrated setting. Three students, one individual with moderate mental retardation and two individuals characterized as at-risk learners, participated in learning sight words through direct instruction and observational-learning conditions. A multiple probe design across three students was combined with a multitreatment design across treatment conditions to assess the impact of instructional variables. Reliability of scoring and procedural integrity were estimated and social validity of outcomes was considered. Findings support the salience of the constant time delay procedure in facilitating word acquisition in small, heterogeneous, and inclusive group learning arrangements. Further, a significant amount of learning through observation occurred for all students under both a general and specific attentional cue condition. A slight but discernible advantage of using the specific cuing strategy of transcribing target and nontarget words was realized.

Attention↗