37 resultados para conditioned fear

em Deakin Research Online - Australia


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Background : Classical Pavlovian fear conditioning has been widely used in preclinical studies to gain insights into anxiety-related disorders. In this study we examined whether pre-existing behavioral differences, and/or behavioral differences displayed during fear induction, predict the severity of the conditioned fear response that can develop after an episode of psychosocial conflict.

Methods : Prior to conditioning, male rats (intruders) were behaviorally assessed using the novel environment exploration and defensive burying tests. These animals were subsequently placed in the territory of an older male (resident) that invariably attacked the intruder.

Results : Upon return to this territory 24 h later, intruders moved less than controls and produced more distress vocalizations, indicating conditioned fear to context. Additionally, analyses revealed that both pre-existing behavioral differences, and the animal’s response during social conflict, predicted the magnitude of the subsequent conditioned fear response. Specifically, animals that engaged in higher levels of novel environment exploration, that exhibited a greater number of defensive burying behaviors, and that demonstrated higher levels of fighting and guarding during social conflict, displayed less evidence of conditioned fear.

Conclusion :
These findings show that the behavioral variability existent within a normal outbred population can predict the magnitude of the conditioned fear response.

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The aim of the current study was to generate socially conditioned fear in two different strains of rat (Wistar, W and Sprague Dawley, SD) using social conflict, in order to investigate whether the magnitude of the conditioned fear responses in each strain was related to behaviour exhibited prior to or during fear induction (i.e. social conflict). On day one of the study, all intruders were assessed for exploratory activity in a novel environment. Twenty four hours following the novel environment test the locomotor activity of the intruders was assessed, while they underwent a single familiarisation exposure to the arena in which the conflict was subsequently to occur in. Twenty-four hours following familiarisation, intruders underwent either a 10 min social conflict or sham conflict session. One day later we examined the response of the intruders when they were returned to the vacant resident's cage. Upon return to the conflict context, we examined the intruder's ultrasonic distress vocalisations and the extent to which locomotor activity was inhibited. We found that W rats displayed significantly more immobility (i.e. conditioned fear) upon return to context than did SD rats (p < 0.05). Importantly, we observed that the differences in the two strains behaviour upon return to context appeared to be related to their quite different patterns of coping behaviour. The results of the current study indicate that preclinical between-strain comparisons potentially have much to offer in regard to understanding the basis of resilience to social stress.

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At present, exposure of a rodent to the odour of a predator is one of the most common animal models of post traumatic stress disorder (PTSD). Despite this, the model remains incompletely characterized, particularly in regard to within subject assessment of major PTSD-like behaviours. In an attempt to redress this situation, we have extensively characterized the two broad categories of behaviour that are considered to characterize PTSD, that is sensitized behaviours such as social withdrawal and hypervigilance and conditioned behaviours such as avoidance of trauma linked cues. Specifically, we determined the presence and duration of both conditioned and sensitized behaviours, in the same cohort of animals, after three exposures to predator odour. Conditioned fear was assessed on the basis of inhibition of locomotor activity upon return to context 2, 7, 14, 21, and 28 days after the last odour exposure session. To assess the impact on sensitization behaviours, we monitored acoustic startle responses and social interaction behaviour 4, 9, 16, 23, and 30 days after the last exposure session. In addition to examining the behavioural consequences associated with odour exposure, we also determined the key brain regions that were activated using ΔFosB immunohistochemistry. Our results show that the two groups of behaviours thought to characterize PTSD (conditioned and sensitized) do not travel together in the predator odour model, with clear evidence of enduring changes in conditioned fear but little evidence of changes in social interaction or acoustic startle. With regard to associated patterns of activity in the brain, we observed that odour-exposed animals exhibited significantly higher numbers of FosB-positive nuclei in only the medial prefrontal cortex (mPFC), a finding that can be viewed as being consistent with the observed behavioural changes.

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Genetic variation at ten microsatellite lociand one anonymous-nuclear locus was assayed for three geographic samples of the criticallyendangered North American cyprinid Notropis mekistocholas (Cape Fear shiner). Despite low abundance of this species, there was little suggestion of small population effects; allele diversity and heterozygosity were relatively high, FIS values within samples were non-significant, and genotypes were distributed in frequencies according to Hardy-Weinberg expectations. Genetic divergence among samples was minimal despite the presence of dams, constructed in the early1900s, that separate the sample sites. This suggests that recent gene flow has been sufficient to inhibit genetic divergence or that gene flow has been reduced but there has been insufficient time for genetic divergence to develop. Tests of heterozygosity excess were non-significant, suggesting that N.mekistocholas in the localities sampled have not undergone recent reductions ineffective population size. Future studies employing larger sample sizes to provide more robust tests of population structure and temporally separated samples to estimate contemporaneous Ne are warranted.

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Worms and other forms of malware have been considered by IT Security firms and large companies for many years as one of the leading threats to the integrity of their data and security. However, several researchers over recent years have been working on creating worms which, instead of causing harm to machines which they infect, or the networks on which the machines reside, actually aid the network and systems administrators. Several uses of these worms have been proposed by these researchers, including, but not limited to, rapid remote patching of machines, network and system administration through use of their unique discovery and propagation methods, actively hunting, and defending against, other forms of malware such as "malevolent" worms, viruses, spyware, as well as increasing reliable communication of nodes in distributed computing. However, there has been no hint of commercial adoption of these worms, which one researcher has described as being due to a fear factor'. This paper concentrates on assessing and delivering the findings of user attitudes towards these worms in an attempt to find out how users feel about these worms, and to try and define and overcome the factors which might contribute to the fear factor'.

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This article examines the experience of low-income women on welfare in Australia and the process of seeking child support from a violent ex-partner, contrasting this with research from the United States and the United Kingdom. Women in Australia who fear ongoing or renewed abuse as a result of seeking child support are eligible for an exemption. However, the exemption policy does not necessarily provide the intended protection of women and children from ongoing abuse and poverty. The exemption policy route also produces an unintended outcome whereby the perpetrators of violence are financially rewarded as they do not have to pay child support. These outcomes are shaped by a complex interaction of personal, cultural and structural forces that make the process of seeking child support for women who have experienced violence extremely problematic. The article demonstrates how in Australia, as in the US and UK policy contexts, the needs of women and their children are compromised by the details of policy specification and the way policies are implemented within the different systems.

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Laws intended to increase protection from sex offenders are often prompted by sensational crimes that provoke public outrage. As public policy, questions have been raised about the legality and effectiveness of these legislative initiatives as enacted in North America, Australasia and the UK since the early 1990s. Mental health professionals involved in the implementation of these laws are faced with ethical concerns that distinguish this area of forensic practice from other clinical roles. This article presents a brief description of the impetus for specific laws allowing for involuntary civil commitment, extended supervision and community notification of sex offenders in different jurisdictions. A model of human rights is then used to consider the ways in which these laws threaten the rights of offenders, and provides a framework for identifying ethical concerns inherent in professional practice in this area.

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Governments use fear to promote political objectives. Through the exaggeration of external threats, fear as conceptualised in the writings of Hobbes, Barry Buzan, David Campbell and others, became a major factor in shaping Australia's post-war foreign and defence policies which were also intended to serve the government's domestic political agenda.

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Context:  Conditioned taste aversion (CTA) is induced by an association of a food item with a negative experience, such as illness, which causes animals to avoid subsequent consumption of that particular food item. Inducing CTA may help reduce depredation rates of threatened fauna where predator population control is undesirable, impractical or unsuccessful.

Aims
:  We investigated whether CTA could be induced among foxes (Vulpes vulpes) to model eggs which mimicked those of the threatened hooded plover (Thinornis rubricollis).

Methods:  
Model eggs treated with a potential CTA-inducing chemical (sodium carbonate) and control eggs free of the agent were exposed to fox depredation for 28 days to simulate a hooded plover incubation period. To investigate whether CTA would persist in wild foxes, we implemented a part-time agent treatment (an initial 14 day exposure period of model eggs with the CTA agent followed by a second 14 day period when model eggs were free of the agent).

Key results:
  Similar intervals to the first depredation event were found for all model eggs regardless of treatment. After the first depredation event by foxes, the rate and likelihood of fox depredation was significantly lower in treated eggs than in control eggs. The likelihood or rate of depredation across the three treatments did not differ between the first and second periods.

Conclusions:
Our results suggest that during an exposure period of at least 28 days, CTA can be induced in wild foxes to eggs on beaches. Our results also suggest that 14 days may be insufficient time for wild foxes to develop a lasting CTA to familiar food items such as eggs.

Implications:
  Treatment of eggs with a CTA-inducing chemical may present a viable alternative to traditional predator control techniques for hooded plovers, as well as other ground-nesting birds, provided that an extended exposure to the CTAinducing agent occurs.

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Background. Physical education (PE) aims to enhance self-esteem, develop sporting interests and to encourage a physically active life-style. However, little is known about how a fear of negative evaluation (FNE), the socially evaluative aspect of social anxiety, affects children's attitudes to PE.

Aim. The aim of the study was to investigate the relationships between perceived athletic competence and FNE within PE lessons, specifically looking at differences between boys and girls and primary and secondary schools.

Sample. The participants were 192 children in three primary schools (N=85, mean age=9.5±1.1 years) and two secondary schools (N=107, mean age=14.5±0.8 years) from rural areas of North Wales and the Midlands region of England.

Methods.
The participants completed the Brief-FNE Scale and the Self-Perception Profile for Children immediately post-lesson on one occasion.

Results. Girls had higher FNE but lower perceptions of athletic competence than did boys. Older girls had higher FNE and lower perceived competence than the remaining three groups. Additionally, a significant and reverse but weak correlation was observed between girls' perceived athletic competence and FNE.

Conclusions.
The findings suggest that girls with a high FNE report lower perceptions of their athletic competence. Individuals who are high in FNE behave in ways to avoid the prospect of being evaluated negatively. However, they may seek feedback from significant others as a signal that unfavourable evaluations have been avoided. Therefore, positive, encouraging feedback used in child-centred learning strategies may foster feelings of competence in boys and girls and could reduce the girls' social anxiety.