SEARCH · PubMed Health

Results for “Avoidance Learning”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,765 records · Page 98Linked to original sources

PubMed1999

Augmentation of taste conditioning by a preconditioned odor.

Five experiments explored facilitated taste-aversion conditioning (odor-mediated taste augmentation), using rats that experienced odor (A) and taste (X) in an A+/AX+ design. Augmentation occurred when the stimuli were presented simultaneously during AX+ conditioning, and significantly weaker conditioning occurred after a sequential presentation (Experiment 1). Experiments 2 and 3 demonstrated that augmented conditioning decreased if the odor aversion was reduced through preexposure or extinction following A+ conditioning. A second-order conditioning explanation was not supported by the results of Experiment 4. Experiment 5 showed that extinction of the odor aversion after AX+ conditioning did not alter the strength of the augmented taste aversion. Odor-mediated taste augmentation is similar to potentiation, in which odor and taste cues operate in a synergistic, not competitive, manner.

Animals↗

PubMed1999

Corticotropin-releasing factor enhances brain-derived neurotrophic factor gene expression to facilitate memory retention in rats.

In the present study, we investigated the effects of corticotropin-releasing factor (CRF) injected into the dentate gyrus (DG) of the hippocampus on brain-derived neurotrophic factor (BDNF) mRNA expression and studied whether N-methyl-D-aspartate (NMDA) receptor mediates the effects of CRF on BDNF mRNA expression in the DG. Since both CRF and BDNF gene expressions are involved in memory processing in rats, we further investigated whether CRF facilitates memory retention through enhanced BDNF mRNA expression in the hippocampus. Effect of direct BDNF injection to the DG on retention performance in rats was also assessed. Results indicated that intra-DG CRF injection produced a dose-dependent (0.1 microg, 1.0 microg and 10 microg) increase in BDNF mRNA level, while intra-DG MK801 injection produced a dose-dependent (0.08 microg, 0.2 microg and 2.0 microg) decrease in BDNF mRNA expression in the DG. MK801, at a dose having no significant effect alone (0.08 microg), significantly antagonized the effect of CRF on BDNF mRNA expression. On the other hand, CRF (1.0 microg) consistently and markedly improved retention performance in rats in an inhibitory avoidance learning task. BDNF antisense oligonucleotide treatment, at a concentration which did not affect retention performance alone (0.5 mM), blocked the memory-enhancing effect of CRF. However, direct and chronic BDNF injection to the DG did not improve memory performance in rats. These results together suggest that at least one of the mechanisms responsible for the memory-facilitating effect of CRF is mediated through enhanced BDNF mRNA expression in the hippocampus. The lack of an effect of intra-DG BDNF injection on memory retention is also discussed.

Animals↗

PubMed2000

Selective associations in day-old chicks: when do CS traces become available for sickness-conditioned learning?

Barber and colleagues (T. A. Barber, A. M. Klunk, P. D. Howorth, M. F. Pearlman, & K. E. Patrick, 1998; T. A. Barber, M. F. Pearlman & K. E. Patrick, 1995) showed that male domestic chicks would not peck a bead presented 15 or more min before a lithium chloride (LiCl) injection, but would peck a bead presented less than 15 min before a LiCl injection. In 4 experiments, the authors (a) confirmed their initial observation, (b) showed that the effect is not due to retrograde amnesia produced by LiCl, and (c) confirmed that memories less than 15 min old are available for other types of learning.

Age Factors↗

PubMed2000

Impairment of long-term potentiation and associative memory in mice that overexpress extracellular superoxide dismutase.

Reactive oxygen species, including superoxide, generally are considered neurotoxic molecules whose effects can be alleviated by antioxidants. Different from this view, we show that scavenging of superoxide with an antioxidant enzyme is associated with deficits in hippocampal long-term potentiation (LTP), a putative neural substrate of memory, and hippocampal-mediated memory function. Using transgenic mice that overexpress extracellular superoxide dismutase (EC-SOD), a superoxide scavenger, we found that LTP was impaired in hippocampal area CA1 despite normal LTP in area CA3. The LTP impairment in area CA1 could be reversed by inhibition of EC-SOD. In addition, we found that EC-SOD transgenic mice exhibited impaired long-term memory of fear conditioning to contextual cues despite exhibiting normal short-term memory of the conditioning experience. These findings strongly suggest that superoxide, rather than being considered exclusively a neurotoxic molecule, should also be considered a signaling molecule necessary for normal neuronal function.

Animals↗

PubMed1975

Pressure sores: an operant conditioning approach to prevention.

A training system for the prevention of pressure sores has been designed to teach the paralytic person to relieve pressure intermittently from his ischium while sitting in a wheelchair. The system automates the training of wheelchair pushups, and conditions the person into exercising, based upon modified avoidance learning procedures. Results indicate that the paralytic person can be trained to pushup intermittently and efficiently using this system, thus reducing the incidence of pressure sore formation. Further long-term study is needed to assess the effectiveness of the training system as a preventative program for pressure sores.

Adult↗

PubMed1996

Gustatory preference-aversion profiles for saccharin, quinine and alcohol in Roman high- and low-avoidance lines.

Rats of the Roman high-(RHA) and low-avoidance (RLA) lines are known to differ in alcohol preference, since the RHA rats freely consume more ethanol than RLA animals. In order to investigate whether this difference in alcohol intake could be due to an alteration of the gustatory quality of ethanol induced by the selection, we compared taste preference and aversion responses of RHA and RLA rats in four procedures: saccharin-water choice; gustatory negative contrast; quinine-water choice and 10% v/v alcohol-water choice. Our results confirm that RHA rats drink more alcohol than RLA rats. In the saccharin-water choice task, RHA rats tended to show higher preference than RLA rats for the most palatable concentrations, while their aversion to the highest concentration of saccharin (50mM) was smaller than the aversion shown by RLA rats. The negative gustatory contrast test did not clearly differentiate the two lines, although only RHA rats showed significant negative contrast. Lastly, while RLA rats showed only aversion to quinine as the concentration increased, RHA rats did not show any aversion and preferred quinine to water at mid-range concentrations. To explain these results three hypotheses are briefly discussed: first, selective breeding for high avoidance learning could have enhanced brain reinforcement processes implicated in the evaluation of palatability. Secondly, selective breeding could have decreased aversiveness to quinine-adulterated solutions, as well as to saccharin and alcohol solutions which include a quinine-like taste component. Lastly, the present results suggest that the RHA rats may be high sensation-seekers whereas RLA animals are low sensation-seekers.

Journal Article↗

PubMed2001

Combined hippocampal and amygdala lesions block learning of a response-independent form of occasion setting.

This study compared rats with dorsal striatal, ventrolateral prefrontal cortical, and combined lesions of the hippocampus and amygdala to sham controls on a conditional discrimination task in which contextual cues modulated a taste aversion. All groups were able to acquire this occasion setting task. The 2nd experiment functionally minimized the stimulus-response component of the paradigm, creating a "tasteless" form of occasion setting. Rats with pretraining lesions of the hippocampus and amygdala were impaired compared with shams on the acquisition of this tasteless occasion setting task. Rats with posttraining combined lesions did not retain the ability to perform the tasteless occasion setting task learned preoperatively. Rats with selective lesions of either the hippocampus or the amygdala alone were not impaired in the acquisition of the tasteless occasion setting task. The findings suggest that this occasion setting task may be learned by several redundant neural systems.

Amygdala↗

PubMed2001

Impairment of mossy fiber long-term potentiation and associative learning in pituitary adenylate cyclase activating polypeptide type I receptor-deficient mice.

The pituitary adenylate cyclase activating polypeptide (PACAP) type I receptor (PAC1) is a G-protein-coupled receptor binding the strongly conserved neuropeptide PACAP with 1000-fold higher affinity than the related peptide vasoactive intestinal peptide. PAC1-mediated signaling has been implicated in neuronal differentiation and synaptic plasticity. To gain further insight into the biological significance of PAC1-mediated signaling in vivo, we generated two different mutant mouse strains, harboring either a complete or a forebrain-specific inactivation of PAC1. Mutants from both strains show a deficit in contextual fear conditioning, a hippocampus-dependent associative learning paradigm. In sharp contrast, amygdala-dependent cued fear conditioning remains intact. Interestingly, no deficits in other hippocampus-dependent tasks modeling declarative learning such as the Morris water maze or the social transmission of food preference are observed. At the cellular level, the deficit in hippocampus-dependent associative learning is accompanied by an impairment of mossy fiber long-term potentiation (LTP). Because the hippocampal expression of PAC1 is restricted to mossy fiber terminals, we conclude that presynaptic PAC1-mediated signaling at the mossy fiber synapse is involved in both LTP and hippocampus-dependent associative learning.

Animals↗

PubMed2002

Ethanol-induced conditioned taste aversion in 15 inbred mouse strains.

This study used a genetic correlational strategy to characterize the neurobiological basis of ethanol's (0, 2, or 4 g/kg) aversive effects as indexed by conditioned taste aversion. Substantial strain differences in taste aversion and hypothermia were observed, but the genetic correlation between these phenotypes was not significant. However, significant genetic correlations were observed between taste aversion and ethanol-related behaviors measured in previous studies, including home-cage ethanol preference (r = .68) and ethanol withdrawal severity (r = -.69). Strains showing stronger taste aversion tended to show lower ethanol preference and higher withdrawal severity. This pattern of findings is consistent with previous studies suggesting a commonality in neurobiological mechanisms underlying these phenotypes. These results do not support the hypothesis that ethanol-induced taste aversion is mediated by the drug's rewarding properties.

Alcohol Drinking↗

PubMed2003

Perceptual learning in flavor aversion: evidence for learned changes in stimulus effectiveness.

Rats were exposed to the compound flavors AX and BX, presented in alternation, and to CX on a separate block of trials. Generalization to BX after aversion conditioning with AX was less than to CX. An equivalent effect was found when the nature of the common element was changed after preexposure but not when the common element was omitted during preexposure, during conditioning and test, or both. Rats conditioned with X alone again showed less aversion to BX than to CX; similarly, rats conditioned with a novel flavor (Y) showed less aversion to BY than to CY. These effects support the proposal that intermixed preexposure to AX and BX enhances the perceptual effectiveness of their unique features, A and B.

Animals↗

PubMed1976

Effects of increased pressures of oxygen and air on short-term memory in mice.

The purpose of this study was to determine the effects of increased oxygen tensions on short-term memory in mice following one-trial, passive-avoidance learning. Neither increased oxygen tensions per se nor 6 ATA air had any measurable deleterious effects on retention of the learned task. Interference with memory of the learned task occurred only when the animals were subjected to oxygen-induced convulsions. Oxygen-induced convulsions did not result in permanent brain damage such that the animals were incapable of learning. Oxygen-induced convulsions following a 2-h interval after learning did not result in a retrograde amnesia. It appears that oxygen-induced convulsions interferes with the consolidation process of memory.

Air Pressure↗

PubMed1992

[Neurophysiologic changes and bound calcium dynamics during the elaboration of associative learning in Helix lucorum].

Neurophysiological effects and dynamics of bound calcium (Ca-b) in command neurons of defense behavior (LP11 and RP11) during food aversion conditioning were studied in snail Helix lucorum. It was found that during associative learning both conditioned reaction and nonspecific facilitation of sensory responses were determined in neurons. The nonspecific facilitation of sensory responses was similar to that found during sensitization development in neurons. However, conditioned response appeared 30 min later than long-term sensitization development. Specific dynamics of the Ca-b level in neurons was obtained after three and more conditioning. The dynamics of the Ca-b level correlated with neurophysiological effects and differed from those measured during sensitization development. It is suggested that molecular mechanisms underlying associative learning and sensitization are different in a command neuron of defense behavior in the snail.

Animals↗

PubMed2003

Effects of two types of restraint stress on the learned behaviour in rats.

To study the effects of stress on cognitive functions, Wistar and Lewis rats were exposed to restraint (immobilization stressor) (IMO) or restraint combined with partial immersion into water (IMO+C). Learned discriminatory avoidance response in Y-maze, with foot-shock as an unconditioned stimulus, was used as a memory test. The latency to enter the correct arm and number of wrong entries were daily recorded during the training period (20 days) until the criterion was reached, which was set at 90% avoidances (choosing the correct arm). After exposure of rats to one of the stressors for 60 min, the rats were returned to the home cage; the latency to enter the safe arm was recorded in 6 daily trials that started 1 h after application of stressor. Both stressors significantly prolonged the avoidance latencies for 2 or 3 days in Wistar and Lewis rats, respectively; then the latencies returned to the values obtained before the stress exposure. In Lewis rats, the latencies more increased after IMO+C than after IMO stressor, and the maximal increase in latencies was higher in Lewis rats than in Wistar rats. The latency did not reach the time limit for foot-shock delivery, and the number of correct choices remained unchanged in both strains. The results indicate that the used restraint stressors did not affect the long-term memory; rather a transient impairment of retrieval can be considered. Further, differences in response of Lewis and Wistar rats may be interpreted by different activity of hypothalamic-pituitary-adrenal axis activity in used strains.

Animals↗

PubMedDate not supplied

[The effect of pulsed cyclical microware radiation on the conditioned behavior of rats].

Research has been carried out to investigate the effects of pulsed cyclical microware exposure (7 GHz, 400 pps, 100 mcs, 10-20 mW/cm2, 10 or 20 cycles of "5 min exposure--4 min pause") on avoidance learning of rats. It was shown that reductions in conditioned behavior after cyclical pulsed microware exposure occurred at an SAR of 2.1 W/kg (10 mW/cm2). It was found the cumulation of the effects of the cycles at prolonged cyclical microwave exposures.

Animals↗

PubMedDate not supplied

[Influence of chronic melipramine administration abolition on locomotion and defensive conditioned reflexes in passive and active avoidance in rats].

The chronic (21 days duration) administration of tricyclic antidepressant melipramine of Wistar rats strain (15 mg/kg daily, intraperitoneally) evoked weight loss of animals. The 7 days after melipramine abolition its sedative effect was observed in the "open field" test by decrease of locomotion and the number of boles. The 7 and 14 days after melipramine abolition the difference between control and melipramine treated animals in passive and active avoidance learning and memory not found. The experimental results comparison with the literature data show, that chronic melipramine administration of intact animals evokes a sedative state. This conclusion does not contradict to idea of punishment function of brain serotoninergic system.

Animals↗

PubMed1991

Perceptual learning in flavour aversion conditioning.

In each of four experiments, rats drank a solution of saline or of lemon and saline shortly before receiving an injection of lithium chloride, and the generalization of the resulting aversion to sucrose or to lemon and sucrose was measured. There was little generalization from saline alone to sucrose alone, and prior exposure to the two solutions had no effect on their discriminability. An aversion conditioned to lemon-saline, however, did generalize to lemon-sucrose, and the extent of this generalization was substantially reduced by prior exposure to the two compound solutions. This perceptual learning effect was partly, but not entirely, attributable to the latent inhibition of the common element, lemon, produced by exposure to the two compounds: animals pre-exposed to lemon alone discriminated between lemon-saline and lemon-sucrose better than animals pre-exposed to saline and sucrose alone; but exposure to the three elements in isolation was not as effective as exposure to the two compound solutions in enhancing their discriminability. The final experiment established that one critical feature of compound pre-exposure is that it involves experience of saline and sucrose in the presence of the same common element. According to an associative theory of perceptual learning, this would result in the establishment of inhibitory associations between saline and sucrose, thus reducing generalization between the two compound solutions.

Animals↗

PubMed2006

[Study on the correlation between adolescents' emotional and behavioral problems and life events].

OBJECTIVE: To study the life events which are correlated with adolescent's emotion and behavior problems, and to provide evidence for clinicians and school staff to develop intervention for those problems. METHODS: Youth's Self Report (YSR) and Adolescent Self-Rating Life Events Check List (ASLEC) were used to assess adolescent's emotional and behavioral problems and life events by 'spot' study. The referred group consisted of 585 patients from 11 to 18 years old in a Mental Health Centre of West China Hospital of Sichuan University from July in 2002 to March in 2004. Level of IQ was above 5th grade of primary school among the study subjects who were willing to fill in the YSR and ASLEC. The non-referred group was selected in a 1280 students cluster-sample from the schools of Chengdu city, whose sex, age and father's career were matched with the referred group. Variance inflation factor (VIF) was used to verify that there was no collinearity to each other in the 6 factors of ASLEC: interpersonal relationship, learning pressure, being punished, losing good adaptation and other. Linear stepwise regression was adopted. RESULTS: The YSR scores in referred group were higher than those in non-referred group, and the referred group had more emotional and behavioral problems than the non-referred one. Partial correlations ranged from 0.124 to 0.418 in referred group, and from 0.104 to 0.388 in non-referred group. Unsatisfied interpersonal relationship, heavy learning pressure, having been punished and poor adaptation were likely to increase the risk of youth's emotional and behavioral problems. CONCLUSION: More attention should be paid to help adolescents in the following areas: solving intrapersonal affairs, relieving pressure from learning, avoiding punishment, and improving ability to fit themselves to their surroundings.

Adaptation, Psychological↗

PubMedDate not supplied

Involvement of neurotransmitter and neuropeptides in behavioural action of some neurohormones.

Investigations were made of the action of ACTH and LH-RH on a number of behavioural paradigms and the possible involvement of neurotransmitters or opiates by pretreatment of receptor blockers in rats and mice. ACTH delayed the extinction of active avoidance behaviour. Atropine and haloperidol blocked this action, whereas phenoxybenzamine and propranolol were ineffective. LH-RH or a highly potent analogue of LH-RH (D-Trp6-LH-RH) decreased the rate of disappearance of dopamine in the hypothalamus following alpha-methyl- paratyrosine inhibition of catecholamine synthesis, and blocked the accumulation of serotonin following MAO inhibition. LH-RH or the analogue attenuated the consolidation of passive avoidance learning. Apomorphine-induced cage-climbing was also inhibited by the LH-RH analogue, but this action was not influenced by naloxone. Open-field activity (ambulation, rearing and grooming) was decreased by the analogue peptide. Naloxone blocked the action on ambulation and rearing, but was ineffective on grooming. The LH-RH analogue caused a dose-dependent increase in cataleptogenic activity. This action could not be blocked with naloxone. The LH-RH analogue suppressed picrotoxin-induced seizures. Naloxone restored the situation to the control level. The data suggested that the effects of some neurohormones are mediated by transmitters or endogenous opiates, and that both peptide-transmitter and peptide-peptide interactions have to be considered in the action of neurohormones.

Adrenocorticotropic Hormone↗