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Studies from the last two decades have pointed to multiple mechanisms of fear. For responding to predators, there is a group of highly interconnected hypothalamic nuclei formed by the anterior hypothalamic nucleus, the ventromedial hypothalamic nucleus and the dorsal premammillary nucleus — the predator-responsive hypothalamic circuit. This circuit expresses Fos in response to predator presence or its odor. Lesion of any component of this system blocks or reduces the expression of fear and consequently defensive behavior when faced with a predator or its cue. However, most of the knowledge about that circuit has been obtained using the rat as a model of prey and the cat as a source of predator cues. In the present study, we exposed mice to strong cat or snake odors, two known mice predators, and then we used the rat exposure test (RET) to study their behavior when confronted with the same predator's odor. Our data point to a differential response of mice exposed to these odors. When Swiss mice were exposed to the cat odor, they show defensive behavior and the predator-responsive hypothalamic circuit expressed Fos. The opposite was seen when they faced snake's odor. The acute odor exposure was not sufficient to activate the mouse predator-responsive hypothalamic circuit and the mice acted like they were not in a stressful situation, showing almost no sign of fear or defensive posture. This leads us to the conclusion that not all the predator cues are sufficient to activate the predator-responsive hypothalamic circuit of mice and that their response depends on the danger that these predators represent in the natural history of the prey. [ABSTRACT FROM AUTHOR]

Barela (Psychological Reports, 110: 173-186, ) presented a novel preparation for the experimental study of classical fear conditioning in goldfish, and successfully employed it in the demonstration of several basic conditioning principles. The present research addressed some basic methodological questions using a modified version of this preparation. Results indicated that the modification made to the visual CS increased its efficacy, and that conditioning to this stimulus was directly related to the number of CS-US trials given, US intensity, and intertrial interval. In addition, conditioning was detected with interstimulus intervals both shorter and longer than those used previously, as well as with an auditory CS. Methodological implications for the future employment of this preparation are discussed. [ABSTRACT FROM AUTHOR]

• Withdrawal from morphine is a learned response. • Morphine withdrawal-related cues elicit fear behaviors. • PrL and BLA modulate learned fear responses. • Reducing GABA in PrL increases morphine withdrawal aversion via BLA. • Morphine withdrawal impairs BLA control over fear output areas. Morphine withdrawal can trigger disruptions in neuronal pathways involved in the modulation and expression of anxiety and fear-related behaviors, particularly those involved in associative learning. When it comes to contextual fear, specific subdivisions of the medial prefrontal cortex (mPFC) regulate the expression of defensive behaviors through projections to specific amygdala (AM) nuclei, such as the prelimbic cortex (PrL). The basolateral nucleus (BLA) of the AM has been shown to be involved in the modulation and expression of associative memories of fear, including those associated with opiate withdrawal-related aversive events. The purpose of this study is to determine the role of GABA mechanisms in the PrL and BLA in startle potentiation and freezing behavior caused by morphine-precipitated withdrawal. Our findings show that morphine withdrawal promotes the emergence of contextual conditioned fear in animals when they are exposed to the same environment where the withdrawal sessions were performed. This suggests that the neural circuits underlying the organism's response to conditioned stressors and the circuits modulating the negative affective states induced by drug withdrawal may overlap. The pharmacological manipulation of GABAergic neurotransmission in the PrL and BLA can reverse contextual fear in morphine-withdrawn rats, an effect that appears to be mediated, at least in part, by GABA A receptors. [ABSTRACT FROM AUTHOR]

Many cats show signs of fear and stress during veterinary examinations and procedures, with environmental stimuli such as noise contributing to these responses. The objective of this study was to investigate the effect of background noise commonly heard in veterinary clinics (people talking, kennel doors shutting, dogs barking) on behavioural and physiological responses in companion cats. In Experiment 1, owned cats underwent a mock physical examination in a veterinary clinic with (n = 16) or without (n = 16) a pre-recorded noise track. A second experiment was conducted to assess cat responses to noise outside of handling and a clinic environment. In Experiment 2, shelter cats were either exposed (n = 15) or not exposed (n = 15) to the same noise track while allowed free movement in a small enclosure. Physiological and behavioural responses previously validated as negative responses in cats (e.g., indicative of fear, stress and aversion) were recorded, and outcome variables were compared between treatments. For both experiments, cats exposed to the noise track showed higher heart and respiratory rates. Noise was not associated with behavioural changes during the physical examination; however, cats who were freely moving showed more behavioural signs of fear and/or stress during noise exposure compared to the no noise conditions. These results show that high levels of background noise elicit physiological stress responses in cats, while ceiling effects of the examination and exposure to the clinic environment likely prevented treatment-related behavioral differences from being detected during the physical examination. It is recommended that those working with cats in environments with high levels of background noise limit cat exposure to these noises to reduce cat fear and stress. • Cat responses to noise were assessed during 1) an examination and 2) freely moving. • Heart and respiratory rate were higher with the noise track in both experiments. • Additional negative behaviours were found in cats exposed during free movement. • During examination, responses were highest during weighing and temperature taking. [ABSTRACT FROM AUTHOR]

Personality and anxiety disorders across species are affected by genetic and environmental factors. Shyness-boldness personality continuum exists across species, including the domestic dog, with a large within- and across-breed variation. Domestic dogs are also diagnosed for several anxiety-related behavioral conditions, such as generalized anxiety disorders, phobias, and separation anxiety. Genetic and environmental factors contributing to personality and anxiety are largely unknown. We collected questionnaire data from a Finnish family dog population (N = 3264) in order to study the associating environmental factors for canine fearfulness, noise sensitivity, and separation anxiety. Early life experiences and exercise were found to associate with anxiety prevalence. We found that fearful dogs had less socialization experiences (p = 0.002) and lower quality of maternal care (p < 0.0001) during puppyhood. Surprisingly, the largest environmental factor associating with noise sensitivity (p < 0.0001) and separation anxiety (p = 0.007) was the amount of daily exercise; dogs with noise sensitivity and separation anxiety had less daily exercise. Our findings suggest that dogs share many of the same environmental factors that contribute to anxiety in other species as well, such as humans and rodents. Our study highlights the importance of early life experiences, especially the quality of maternal care and daily exercise for the welfare and management of the dogs, and reveals important confounding factors to be considered in the genetic characterization of canine anxiety. [ABSTRACT FROM AUTHOR]

The article focuses on behavior of cats. Because the ears are highly sensitive, a cat that is frightened tends to hold them back, possibly to protect them from anticipated harm. Cats draw conclusions related to the relative safety of an experience on the basis of experiences. They do not express their emotions and rarely tell what they require.

Large mammalian carnivores create areas perceived as having high and low risk by their ungulate prey. Human activities can indirectly shape this landscape of fear by altering behavior and spatial distribution of carnivores. We studied how red deer perceive the landscape of fear in an old-growth forest system (Białowieża Primeval Forest, Poland) both at large and fine spatial scale. Camera traps were placed at locations with and without tree logs (fine-scale risk factor) and at different distances from the core of a wolf territory and human settlements (large-scale riskfactor). Red deer avoided coming close to large tree logs and increased their vigilance levels when they were present in close vicinity. The strength of these effects depended on the distance to the wolf core area; deer perceived tree logs as more risky when wolves were more often present. Hence, tree logs inside wolf core areas create fine-scale patches of fear with reduced deer browsing pressure, thereby enhancing chances for successful tree recruitment. Human presence shapes this landscape of fear as wolf core areas are located far from human settlements. This "human shadow" on predator-prey interactions is therefore an important component that should be taken into account in human-dominated landscapes. [ABSTRACT FROM AUTHOR]

Selective sensitization has been proposed as an alternative explanation for enhanced responding to animal fear-relevant stimuli-snakes and spiders-during extinction of Pavlovian fear conditioning. The current study sought to replicate the phenomenon using a shock workup procedure as the sensitizing manipulation and to extend it to interpersonal and intergroup fear-relevant stimuli-angry faces and other-race faces. Assessment of selective sensitization was followed by a one-trial fear learning procedure. Selective sensitization, larger electrodermal responses to fear-relevant than to control stimuli after sensitization, or a larger increase in electrodermal responding to fear-relevant than to control stimuli after sensitization was observed across stimulus domains. However, the one-trial fear learning procedure failed to provide evidence for enhanced fear conditioning to fear-relevant stimuli. One-trial fear learning was either absent or present for fear-relevant and nonfear-relevant stimuli. The current study confirms that electrodermal responses to fear-relevant stimuli across stimulus domains are subject to selective sensitization. [ABSTRACT FROM AUTHOR]

A web-based survey was conducted to estimate prevalence of noise sensitivity in 17 dog breeds in Norway ( n = 5257). Major focus was on noise from fireworks, loud noises (bang/gunshots), thunderstorms and heavy traffic. The study also investigated risk factors as well as correlation with some other fear responses. On average approximately 23% of the dogs were reported to be fearful of noises. Fear in situations with fireworks had the highest frequency; situations with loud noises/gunshots, thunderstorms and heavy traffic following in decreasing order. Across the 17 breeds there was significant ( p < 0.01) differences in the frequencies of fearful dogs. Norwegian Buhund, Irish Soft Coated Wheaten Terrier and Lagotto Romagnolo were breeds that had the highest frequency of noise sensitivity while Boxer, Chinese Crested and Great Dane had lower frequencies of fear created by noise. There was a significant trend of increasing fear with older age. Response to fireworks, loud noises/gunshots and thunderstorms frequently co-occurred. Female dogs had higher odds of noise sensitivity compared to male dogs (OR = 1.3 p < 0.001), and neutered dogs had higher odds of being fearful of noises than intact dogs (OR = 1.73 p < 0.001). The dogs most fearful of noises also had higher odds of showing separation related behavior, being fearful in novel situations and required longer time to calm down after a stressful event compared to dogs less fearful of noises. [ABSTRACT FROM AUTHOR]

The objective of the study was to assess the effects of a dog-appeasing pheromone (DAP) collar in reducing sound-induced fear and anxiety in a laboratory model of thunderstorm simulation. Twenty-four beagle dogs naïve to the current test were divided into two treatment groups (DAP and placebo) balanced on their fear score in response to a thunderstorm recording. Each group was then exposed to two additional thunderstorm simulation tests on consecutive days. Dogs were video-assessed by a trained observer on a 6-point scale for active, passive and global fear and anxiety (combined). Both global and active fear and anxiety scores were significantly improved during and following thunder compared with placebo on both test days. DAP significantly decreased global fear and anxiety across 'during' and 'post' thunder times when compared with baseline. There was no significant improvement in the placebo group from baseline on the test days. In addition, the DAP group showed significantly greater use of the hide box at any time with increased exposure compared with the placebo group. The DAP collar reduced the scores of fear and anxiety, and increased hide use in response to a thunder recording, possibly by counteracting noise-related increased reactivity. [ABSTRACT FROM AUTHOR]

The poultry industry is currently undergoing a shift to alternative lighting sources as incandescent lights become less available. While LED and CFL bulbs both have associated increased energy savings, they may affect the bird's growth and well-being differently as they output different light spectrums. To determine how different LED bulbs and a CFL bulb affected broiler performance, behavior, stress, and overall wellbeing, we conducted an experiment using Cobb broiler chickens (N = 360). A NextGen LED bulb (NextGen), a Once Innovations LED bulb (Once), and a dimmable CFL (CFL) were used, all of which had different spectral outputs. Growth and feed conversion, several stress measures, fear tests, organ characteristics, and animal welfare assessment parameters were collected to determine how each light type affected animal well-being. LED treatments had shorter (P < 0.05) latency to right during tonic immobility testing when compared to the CFL treatment; however, no other differences (P > 0.05) were seen in the other fear tests. The Once treatment resulted in lower composite physical asymmetry, heterophil/lymphocyte ratio, and basal plasma corticosterone concentrations compared to the other treatments (P < 0.05). Differences were observed in some organ measures; notably in the eye dimensions of the Once treatment. The Once treatment also had lower (P < 0.05) plumage, hock, and footpad scores when compared to CFL treatment, while the Nextgen treatment had lower (P < 0.05) plumage and hock scores than the CFL treatment but no difference between the two was seen in foot pad scores. Weight at the end of the growout was not affected by bulb type, however, both LED treatments had increased feed conversion (P < 0.05). These results indicate that LEDs can result in better well-being and feed conversion when compared to CFLs. It is also notable that the LEDs did not have the same effects and this is likely due to the spectrum of light each creates. LEDs were shown to improve production and well-being of broiler chickens compared to CFLs. [ABSTRACT FROM AUTHOR]

Commercial turkey production has increased greatly in recent decades. Along with increased production, problems with turkey meat quality have also increased. Research with other species has demonstrated that differences in meat quality exist among pigs and cattle differing in characteristics such as fearfulness. However, associations between fear responses and postmortem (PM) muscle characteristics related to the meat quality of turkeys have not been examined. This study evaluated the test-retest repeatability of responses of male commercial (COMM) and randombred (RB) turkeys in an open field (OF) test, which is used to assess fear and activity levels of poultry. Another objective of this study was to evaluate the relationship between behavioral OF responses and PM breast muscle characteristics (pH and R-value) that are related to meat quality. Thirdly, this study evaluated differences in pH and R-value between the turkey lines. Male COMM and RB turkeys were each housed in groups in 4 pens. Turkeys were individually tested in an OF (2.74 × 2.74 m, divided into 81 squares) at 1, 4, and 11 wk (COMM N = 27; RB N = 33). Turkeys were then grouped into clusters based on a cluster analysis of OF behavior. Turkeys were processed and meat quality characteristics were evaluated at 15-17 wk for COMM and 20-21 wk for RB turkeys. Results were analyzed using a mixed model (SAS 9.4). Breast muscle pH and R-value did not differ between genetic lines, and there were no differences in pH and R-value among clusters within genetic lines. These findings suggest that OF responses measured during rearing are not related to PM breast muscle pH and R-value, which ultimately affect meat quality. Further research is needed to assess whether other types of fear responses are associated with meat quality and whether differences in R-value between genetic lines are associated with differences in other meat quality characteristics. [ABSTRACT FROM AUTHOR]

The "landscape of fear" model has been proposed as a unifying concept in ecology, describing, in part, how animals behave and move about in their environment. The basic model predicts that as an animal's landscape changes from low to high risk of predation, prey species will alter their behavior to risk avoidance. However, studies investigating and evaluating the landscape of fear model across large spatial scales (tens to hundreds of thousands of square kilometers) in dynamic, open, aquatic systems involving apex predators and highly mobile prey are lacking. To address this knowledge gap, we investigated predator- prey relationships between tiger sharks (Galeocerdo cuvier) and loggerhead turtles (Caretta caretta) in the North Atlantic Ocean. This included the use of satellite tracking to examine shark and turtle distributions as well as their surfacing behaviors under varying levels of home range overlap. Our findings revealed patterns that deviated from our a priori predictions based on the landscape of fear model. Specifically, turtles did not alter their surfacing behaviors to risk avoidance when overlap in shark-turtle core home range was high. However, in areas of high overlap with turtles, sharks exhibited modified surfacing behaviors that may enhance predation opportunity. We suggest that turtles may be an important factor in determining shark distribution, whereas for turtles, other life history trade-offs may play a larger role in defining their habitat use. We propose that these findings are a result of both biotic and physically driven factors that independently or synergistically affect predator-prey interactions in this system. These results have implications for evolutionary biology, community ecology, and wildlife conservation. Further, given the difficulty in studying highly migratory marine species, our approach and conclusions may be applied to the study of other predator- prey systems. [ABSTRACT FROM AUTHOR]

To be able to reproduce, animals need to survive and interact with an ever changing environment. Therefore, they create a cognitive representation of that environment, from which they derive expectancies regarding current and future events. These expected events are compared continuously with information gathered through exploration, to guide behaviour and update the existing representation. When a moderate discrepancy between perceived and expected events is detected, exploration is employed to update the internal representation so as to alter the expectancy and make it match the perceived event. When the discrepancy is relatively large, exploration is inhibited, and animals will try to alter the perceived event utilizing aggression or fear. The largest discrepancies are associated with a tendency to flee. When an exploratory, fear, or aggressive behaviour pattern proofs to be the optimal solution for a particular discrepancy, the response will become conditioned to events that previously preceded the occurrence of that discrepancy. When primary needs are relatively low, animals will actively look for or create moderately violated expectancies in order to learn about objects, behaviour patterns, and the environment. In those situations, exploratory tendencies will summate with ongoing behaviour and, when all primary needs are satiated, may even be performed exclusively. This results in behavioural variability, play, and active information-seeking. This article is part of a Special Issue entitled: In Honor of Jerry Hogan. [ABSTRACT FROM AUTHOR]

Evolution has endowed all humans with a continuum of innate, hard-wired, automatically activated defense behaviors, termed the defense cascade. Arousal is the first step in activating the defense cascade; flight or fight is an active defense response for dealing with threat; freezing is a flight-or-fight response put on hold; tonic immobility and collapsed immobility are responses of last resort to inescapable threat, when active defense responses have failed; and quiescent immobility is a state of quiescence that promotes rest and healing. Each of these defense reactions has a distinctive neural pattern mediated by a common neural pathway: activation and inhibition of particular functional components in the amygdala, hypothalamus, periaqueductal gray, and sympathetic and vagal nuclei. Unlike animals, which generally are able to restore their standard mode of functioning once the danger is past, humans often are not, and they may find themselves locked into the same, recurring pattern of response tied in with the original danger or trauma. Understanding the signature patterns of these innate responses--the particular components that combine to yield the given pattern of defense--is important for developing treatment interventions. Effective interventions aim to activate or deactivate one or more components of the signature neural pattern, thereby producing a shift in the neural pattern and, with it, in mind-body state. The process of shifting the neural pattern is the necessary first step in unlocking the patient's trauma response, in breaking the cycle of suffering, and in helping the patient to adapt to, and overcome, past trauma. [ABSTRACT FROM AUTHOR]

The individual typological features of conditioned reflex fear were studied in groups of active and passive rabbits selected on the basis of analysis of their behavior in the open field and dark-light boxes by developing a classical conditioned reflex using a combination of a light (4 sec) and electrocutaneous stimulation of the hindpaws (10 Hz, 0.5 sec). Changes in respiratory and heart rates in the animals in response to stimulus combinations during training were analyzed. Conditioned defensive responses to light (freezing) were associated with reductions in respiratory and heart rates occurring in response to the light, i.e., before electrocutaneous stimulation. Active rabbits contrasted with passive rabbits in showing greater motor reactions, higher heart rates, delayed onset of conditioned reflex respiratory slowing to a later stage of training, and the absence of persistent bradycardia. Thus, judging from the these few autonomic measures, active animals experienced lower levels of fear than passive animals. The active and passive behavioral strategies persisted after training. [ABSTRACT FROM AUTHOR]

The article discusses the role of paravalbumin-positive (PV+) excitatory projection neurons in the superior colliculus (SC) of mice in detecting looming objects and triggering fear responses,. According to the authors, these neurons projected to several different brain areas including the parabigeminal nucleus (PBGN), which is an intermediate area leading to the amygdala. Other topics include conditioned aversion and depression-related behaviors.

The purposes of this study were to examine the duration of induced tonic immobility (a reliable fear indicator considered a passive anti-predator behavioural trait) and two stress indicators (heterophil to lymphocyte ratio, and fluctuating asymmetry of leg length, middle-toe length, and wing length) in females and males of the red-legged partridge, and to analyze the differences between pure and hybrid populations. A total of 132 birds (66 pure and 66 hybrid partridges; 48 females and 84 males) at 52 weeks of age were used. There was a significant difference between pure and hybrid birds in tonic immobility duration ( P < 0.005) and heterophil to lymphocyte ratio ( P < 0.02), the duration being longer and the ratio being higher in the pure group of birds. There was a significant difference between pure and hybrid birds in the relative fluctuating asymmetry of middle toe length ( P < 0.002) and the combined fluctuating asymmetry value of the three traits ( P < 0.03). There were no significant differences between sexes in any indicator of fear or stress. Thus, pure red-legged partridges were more fearful, stressed, and asymmetrical than hybrid partridges, having increased tonic immobility duration, heterophil to lymphocyte ratio, and relative fluctuating asymmetry. Results indicate that levels of fear and stress, e.g. tonic immobility duration, heterophil to lymphocyte ratio, and fluctuating asymmetry, are higher in the pure partridge, and that fear and stress indicators have been modified in hybrid partridges leading to more passive animals. [ABSTRACT FROM AUTHOR]

Following reports of emotional psychopathology in children and adults exposed to organophosphates, the effects of postnatal chlorpyrifos (CPF) on fear-conditioning and depression-like behaviors were tested in adult mice. Concomitant changes in expression of mRNA for synaptic and soluble splice variants of acetylcholinesterase (AChE) were examined in mouse pups and adults of the Balb/C and C57Bl/6 (B6) strains, which differ in their behavioral and hormonal stress response. Mice were injected subcutaneously with 1 mg/kg CPF on postnatal days 4-10 and tested as adults for conditioned fear, sucrose preference, and forced swim. Acetylcholinesterase activity was assessed in the brains of pups on the first and last day of treatment. Expression of soluble and synaptic AChE mRNA was assessed in brains of treated pups and fear-conditioned adults using real-time PCR. Adult Balb/C mice exposed postnatally to CPF showed exacerbated fear-conditioning and impaired active avoidance. Adult B6 mice exposed postnatally to CPF showed a more specific fear response to tones and less freezing in the inter-tone intervals, in contrast to the vehicle-pretreated mice. Chlorpyrifos also attenuated sweet preference and enhanced climbing in the forced swim test. Chlorpyrifos-treated mice had increased expression of both synaptic and readthrough AChE transcripts in the hippocampus of Balb/C mice and decreased expression in the amygdala following fear-conditioning. In conclusion, postnatal CPF had long-term effects on fear and depression, as well as on expression of AChE mRNA. These changes may be related to alteration in the interaction between hippocampus and amygdala in regulating negative emotions. [ABSTRACT FROM AUTHOR]

It is generally assumed that there is a relationship between feather pecking, fear, feather condition and laying performance criteria in laying hens. This hypothesis was tested in a F2-cross of high (HFP) and low (LFP) feather pecking birds of White Leghorn origin. A total of 967 birds were first observed for the number of bouts of severe feather pecks delivered (FPD) and received (FPR) when kept in groups of random composition. The whole population was split for FPD in HFP and LFP using the threshold of ≥ 2 (HFP) and < 2 (LFP). The birds clearly differed in FPD but there was no significant difference for FPR between HFP and LFP. The subgroups were subjected to a pencil test at 29 weeks of age. At 26 weeks and 39 weeks of age body weight was measured and feather condition scored in different body parts (neck, breast, wings, vent and tail) using a scale from 0--4 (0 = worse, 4 = best). In addition the birds were tested for their feather eating behaviour and their laying performance criteria (hen-day egg production %, egg weight, feed consumption per day and FCR) at 29 weeks of age. In contrast to our expectation HFP birds showed a significant better plumage condition at 39 weeks of age than LFP birds. There were differences in feather scores at both ages for wings and tail. There were no differences between subgroups in the body weight at neither age. There were also no differences in the pencil test. But HFP birds showed a significant higher number of eaten feathers than LFP birds. This is in line with many other studies. But the difference was not as large as reported in previous studies. In contrast to our expectation there were no significant differences between the subgroups in performance, feed intake and FCR although LFP birds showed a significant poorer feather condition than HFP birds at 39 weeks of age. There were, however, negative correlations between feather score, performance, feed consumption and FCR within subgroups.Obviously there is no consistent relationships between feather pecking, fear, feather condition and performance criteria. [ABSTRACT FROM AUTHOR]

Incompatibility between the behaviour of companion cats and dogs and the behavioural expectations of their owners/caregivers remains the most common reason for the euthanasia, abandonment or re-homing of companion animals. In the absence of behavioural guidance from the veterinary team regarding their companion animal's emotional and behavioural development, owners are unlikely to assist pets to develop coping strategies that are compatible with owner expectations. As a result, the majority of young animals find themselves relying on innate, adaptive survival skills to deal with their exposure to anxiety, fear and frustration. This article discusses the resulting frequent or chronic stress experienced by companion animals, both in the home and in the veterinary practice, and the associated implications for animal health and welfare. The handling and restraint of such animals creates considerable difficulties for practice staff, and when pet-human relationships break down to such an extent that pets are relinquished, practices lose substantial income. A second article will examine the practicalities of handling the stressed patient. [ABSTRACT FROM AUTHOR]

Stress-enhanced fear learning (SEFL) refers to the long-lasting nonassociative sensitization produced by intense stress (e.g., repeated and unpredictable footshock) that results in increased fear learning to a mild conditioning regimen (e.g., one shock). SEFL experiments suggest that one component of posttraumatic behavior is inappropriately strong fear conditioning occurring to relatively mild stressors. Past reports of SEFL have used the same intensity (1 mA) of footshock to cause both the sensitization and conditioning of new fear. SEFL would be a particularly problematic component of posttrauma behavior if intense stress results in substantial fear conditioning under conditions that would not normally support conditioning. Therefore, we determined if SEFL occurred when the conditioning shock was substantially milder than the SEFL-inducing shock. The results indicate that exposure to a sensitizing regimen of shock can convert a mild footshock that normally does not support measurable levels of fear conditioning into one that causes substantial learned fear. Moreover, as the intensity of single footshock increases, so does the capacity of the prior stressor to contribute to the sensitization of fear responses. Consistent with prior studies, males acquired and retained a greater level of fear conditioning than female rats, however the level of sensitization did not differ between sexes. [ABSTRACT FROM AUTHOR]

Although post-traumatic stress disorder (PTSD) and addiction are very different disorders, both are characterized by hyperreactivity to trauma- or drug-related cues, respectively. We investigated whether an appetitive conditioning task, Pavlovian conditioned approach, which predicts vulnerability to reinstatement of cocaine-seeking, also predicts fear incubation, which may be a marker for vulnerability to PTSD. We classified rats based on whether they learned to approach and interact with a food predictive cue (sign-trackers), or, whether upon cue presentation they went to the location of impending food delivery (goal-trackers). Rats were then exposed to extensive Pavlovian tone-shock pairings, which causes the fear response to increase or “incubate” over time. We found that the fear incubation effect was only present in sign-trackers. The behavior of goal-trackers was more consistent with a normal fear response–it was most robust immediately after training and decayed slowly over time. Sign-trackers also had lower levels of brain-derived neurotrophic factor (BDNF) protein in the prefrontal cortex than goal-trackers. These results indicate that, while many factors likely contribute to the disproportionate co-occurrence of PTSD and substance abuse, one such factor may be a core psychological trait that biases some individuals to attribute excessive motivational significance to predictive cues, regardless of the emotional valence of those cues. High levels of BDNF in the prefrontal cortex may be protective against developing excessive emotional and motivational responses to salient cues. [ABSTRACT FROM AUTHOR]

Herbivores frequently have to make trade-offs between two basic needs: the need to acquire forage and the need to avoid predation. One manifestation of this trade-off is the 'landscape of fear' phenomenon - wherein herbivores avoid areas of high perceived predation risk even if forage is abundant or of high quality in those areas. Although this phenomenon is well established among invertebrates, its applicability to terrestrial large herbivores remains debated, in part because experimental evidence is scarce., This study was designed to (i) experimentally test the effects of tree density - a key landscape feature associated with predation risk for African ungulates - on herbivore habitat use and (ii) establish whether habitat use patterns could be explained by trade-offs between foraging opportunities and predation risk avoidance., In a Kenyan savanna system, replicate plots dominated by the tree Acacia drepanolobium were cleared, thinned or left intact. Ungulate responses were measured over four years, which included years of moderate rainfall as well as a severe drought., Under average rainfall conditions, most herbivores (primarily plains zebra, Grant's gazelle and hartebeest) favoured sites with fewer trees and higher visibility - regardless of grass production - while elephants (too large to be vulnerable to predation) favoured sites with many trees. During the drought, however, herbivores favoured sites that had high grass biomass, but not high visibility. Thus, during the drought, herbivores sought areas where food was more abundant, despite probable higher risk of predation., These results illustrate that the 'landscape of fear', and the associated interactions between top-down and bottom-up effects, is not static, but rather shifts markedly under different conditions. Climate thus has the potential to alter the strength and spatial dynamics of behaviourally mediated cascades in large herbivore systems. [ABSTRACT FROM AUTHOR]

The article discusses the fear-related behavior of orangutans and gorillas against snakes. Topics discussed include study of fear-related behavior of orangutans and gorillas at the London Zoo in London, England, observations of wild Bornean Orangutans like Pongo pygmaeus wurmbii's reaction to snakes, cobras and pitvipers, and need for studying population of wild snakes in a zoo to prevent this behavior in orangutans and gorillas.

Several types of questionnaires are in use to measure fear-related behaviour in family dogs. Our aim was to develop a general questionnaire based on relevant previous studies in order to facilitate the standardization of measurements of fear-related behaviour in dogs (social fear, non-social fear, separation problems, anxiety/destructiveness and neuroticism). We investigated which aspects of fear do emerge as distinct factors when measuring fear in dogs with our consensus questionnaire. We developed the questionnaire by piercing together seven discrete fear-related factors from six previous studies representing different aspects of fear. Our final questionnaire consisted of 56 items and was filled out by 833 Hungarian pet dog owners. Principal component analysis was applied to explore the factorial structure of the questionnaire scores. The original seven factors used in developing the questionnaire did not emerged as discrete factors. Instead, we found four factors (33 questionnaire items) labeled as neuroticism (CRA = 0.87), dog-directed fear (CRA = 0.84), human-directed fear (CRA = 0.90) and separation-related behavior (CRA = 0.83). The effects of demographic and dog keeping characteristics on these factors were also tested by generalized linear models (GLMs). For example, toy dogs had a higher risk to show neuroticism and dog-directed fear. Female owners were more frequently reporting human-directed fear in their dogs. Female dogs showed higher level of dog-directed fear. Older dogs score was higher on neuroticism and neuroticism correlated with the time of acquisition. The standardization of specific trait measures provides an advantage to the researchers in constructing further, more specific tools and offers a greater comparability of research across dog and human populations. [ABSTRACT FROM AUTHOR]

Current treatments for trauma-related disorders remain ineffective for many patients. 1,2 Fear extinction deficiency is a prominent feature of these diseases, 3 and many behavioral treatments rely on extinction training. 4,5 However, in many patients, therapy is followed by a relapse of symptoms, and the underpinnings of such interindividual variations in vulnerability to relapse remain unknown. 6–8 Here, we modeled interindividual differences in post-therapy fear relapse with an ethologically relevant trauma recovery paradigm. After fear conditioning, male rats underwent fear extinction while foraging in a large enriched arena, permitting the expression of a wide spectrum of behaviors. An automated multidimensional behavioral assessment revealed that post-conditioning fear response profiles clustered into two groups: some animals expressed fear by freezing more, whereas others darted more, as if fleeing from danger. Remarkably, the tendency of an animal to dart or to freeze after CS presentation during the first extinction session was, respectively, associated with stronger or weaker fear renewal. Moreover, genome-wide transcriptional profiling revealed that these groups differentially regulated specific sets of genes, some of which were previously implicated in anxiety and trauma-related disorders. Our results suggest that post-trauma behavioral phenotypes and the associated gene expression landscapes can serve as markers of fear relapse susceptibility and thus may be instrumental for future development of more effective treatments for psychiatric patients. • Multidimensional behavioral scoring in an ethologically rich fear extinction paradigm • Two distinct post-conditioning fear response profiles converging over extinction training • Post-trauma freezing or darting predicts level of vulnerability to fear renewal • Respective phenotypes characterized by different gene expression profiles in vmPFC Demars et al. model interindividual differences in fear relapse with an ethologically relevant trauma recovery paradigm. They show that post-trauma behavioral phenotypes cluster into two groups: the tendencies to dart or to freeze at early extinction are associated with stronger or weaker fear renewal and with distinct transcriptomic profiles. [ABSTRACT FROM AUTHOR]

The article describes the case of a 4-year-old male Jack Russell Terrier referred for evaluation because of aggressive behavior directed toward unfamiliar people. Topics covered include the forms of aggressive behavior observed in the dog, a discussion of physical examination findings and laboratory results, fearful body postures showed by the dog which confirmed the diagnosis of fear-related aggression, and outcome following positive reinforcement training sessions.

Rationale: The aberrant regulation of serotonin (5-HT) and dopamine (DA) in the brain has been implicated in neuropsychiatric disorders associated with marked impairments in empathy, such as schizophrenia and autism. Many psychiatric drugs bind to both types of receptors, and the anterior cingulate cortex (ACC) is known to be centrally involved with empathy. However, the relationship between the 5-HT/DA system in the ACC and empathic behavior is not yet well known. Objectives: We investigated the role of 5-HT/DA in empathy-like behavior and in the regulation of ACC neural activity. Methods: An observational fear learning task was conducted following microinjections of 5-HT, DA, 5-HT and DA, methysergide (5-HT receptor antagonist), SCH-23390 (DA D receptor antagonist), or haloperidol (DA D receptor antagonist) into the mouse ACC. The ACC neural activity influenced by 5-HT and DA was electrophysiologically characterized in vitro and in vivo. Results: The microinjection of haloperidol, but not methysergide or SCH-23390, decreased the fear response of observing mice. The administration of 5-HT and 5-HT and DA together, but not DA alone, reduced the freezing response of observing mice. 5-HT enhanced delta-band activity and reduced alpha- and gamma-band activities in the ACC, whereas DA reduced only alpha-band activity. Based on entropy, reduced complexity of ACC neural activity was observed with 5-HT treatment. Conclusions: The current results demonstrated that DA D receptors in the ACC are required for observational fear learning, whereas increased 5-HT levels disrupt observational fear and alter the regularity of ACC neural oscillations. [ABSTRACT FROM AUTHOR]

For foraging herbivores, both food quality and predation risk vary across the landscape. Animals should avoid low-quality food patches in favour of high-quality ones, and seek safe patches while avoiding risky ones. Herbivores often face the foraging dilemma, however, of choosing between high-quality food in risky places or low-quality food in safe places. Here, we explore how and why the interaction between food quality and predation risk affects foraging decisions of mammalian herbivores, focusing on browsers confronting plant toxins in a landscape of fear. We draw together themes of plant-herbivore and predator-prey interactions, and the roles of animal ecophysiology, behaviour and personality. The response of herbivores to the dual costs of food and fear depends on the interplay of physiology and behaviour. We discuss detoxification physiology in dealing with plant toxins, and stress physiology associated with perceived predation risk. We argue that behaviour is the interface enabling herbivores to stay or quit food patches in response to their physiological tolerance to these risks. We hypothesise that generalist and specialist herbivores perceive the relative costs of plant defence and predation risk differently and intra-specifically, individuals with different personalities and physiologies should do so too, creating individualised landscapes of food and fear. We explore the ecological significance and emergent impacts of these individual-based foraging outcomes on populations and communities, and offer predictions that can be clearly tested. In doing so, we provide an integrated platform advancing herbivore foraging theory with food quality and predation risk at its core. [ABSTRACT FROM AUTHOR]

The acute glucocorticoid stress response is presumed to facilitate escape from life-threatening situations such as predation and thus it is assumed to be linked to fitness. However, the fitness effects of glucocorticoid reactivity remain controversial, as these effects may be context-dependent. Individuals differing in their emphasis on current versus future reproduction may differ in their risk-taking under threat of predation; this variation in risk-taking may be mediated by variations in stress reactivity. We set out to test whether predation risk (island- and year-specific proportion of depredated nests) modified the relationships between stress responsiveness and current reproductive investment (clutch weight) and between stress responsiveness and reproductive success (viable proportion of the clutch) in the long-lived female eider S omateria mollissima. This study system shows large spatial and annual fluctuations in predation risk, indexed by the annual island-specific proportion of depredated nests. The capture stress-related corticosterone output was attenuated with increasing clutch weight under low predation pressure but elevated under severe predation pressure, and females in well-concealed nests had lower stress responsiveness. The viable proportion of the clutch decreased with increasing corticosterone reactivity under low to moderate predation pressure, but slightly increased under severe predation pressure. The acute stress response may thus mediate adaptive plasticity; dampened stress reactivity may ensure successful reproduction under low predation threat or in nest sites reducing detection by visual predators, whereas preparing for potential attacks may be favoured under elevated predation risk. [ABSTRACT FROM AUTHOR]

A series of experiments used rats to examine renewal and reinstatement of extinguished second-order conditioned fear (freezing) responses. The initial experiment demonstrated that freezing responses to a stimulus (S2) were contingent on its pairings with a second stimulus (SI) and on the prior pairings of SI and an aversive unconditioned stimulus (US). Subsequent experiments showed that these freezing responses extinguished across S2 alone presentations, but were renewed when: S2-S1 pairings and S2 alone presentations occurred in the same context and testing of S2 occurred elsewhere; S2--SI pairings and testing were in the same context and S2 alone presentations were elsewhere; and when S2-S1 pairings, S2 alone presentations and testing occurred in different contexts. Freezing responses to an extinguished S 1 were reinstated by US alone presentations. However, these responses were not reinstated to an extinguished S2 by US or SI alone presentations, and, conversely, freezing to a nonextinguished S2 was unaffected by extinction of SI. The results were interpreted to mean that S2-S1 pairings produced an association between S2 and the fear responses elicited by SI and that extinction of this association is controlled by context. The failure to reinstate fear responses to S2 is discussed in terms of theories developed to explain reinstatement of SI. [ABSTRACT FROM AUTHOR]

The present study compared behaviour, fear and stress levels of 456 crossbred rabbits reared in bicellular wire-net cages (2 rabbits/cage) with top and wire floor or open-top collective pens (20 to 54 rabbits/pen) with wooden slatted floor. The effect of pen size (small vs. large) and stocking density (12 vs. 16 rabbits/m²) in collective pens was also evaluated. The rabbits kept in collective pens rested more than those in bicellular cages (82.1% vs. 77.6% of observed time; P<0.01), spent less time feeding (7.8% vs. 10.9%), allo-grooming (0.65% vs. 1.58%) and more time moving (0.81% vs. 0.35%) (P<0.01). The percentage of rabbits sensitive in the tonic immobility test was lower in rabbits kept collectively compared to those in bicellular cages (76.6% vs. 93.8%; P=0.03). In the open field test, the rabbits kept in collective pens moved less (40.4 s vs. 57.2 s; P<0.001) and explored the arena for a shorter time (345 s vs. 371 s; P<0.001) than rabbits housed in bicellular cages; instead, these rabbits stood still for a longer period of time (82.1 s vs. 38.7 s; P<0.001). The rabbits kept in collective pens displayed a higher hair corticosterone level (15.7 ng/g vs. 6.7 ng/g for rabbits from the cages; P<0.001). Within collective housing systems, stocking density had no effect whereas increasing pen size numerically reduced the time rabbits spent eating (8.30% vs. 6.55%), self-grooming (6.39% vs. 5.47%) and time spent resting (81.1% vs. 84.1%). In conclusion, rabbits housed in collective pens displayed a more complete behavioural pattern, despite resting more; they were more bold toward humans, but more fearful in a new environment than rabbits from cages. In the tested conditions, pen size and stocking density within collective systems exerted only a weak effect on behaviour, fear and stress levels of meat rabbits. [ABSTRACT FROM AUTHOR]

Factors determining individuality are still poorly understood. Rodents are excellent model organisms to study individuality, due to a rich behavioral repertoire and the availability of well-characterized isogenic populations. However, most current behavioral assays for rodents have short test duration in novel test environments and require human interference, which introduce coercion, thereby limiting the assessment of naturally occurring individuality. Thus, we developed an automated behavior system to longitudinally monitor conditioned fear for assessing PTSD-like behavior in individual mice. The system consists of a safe home compartment connected to a risk-prone test compartment (TC). Entry and exploration of the TC is solely based on deliberate choice determined by individual fear responsiveness and fear extinction. In this novel ethological assay, C57BL/6J mice show homogeneous responses after shock exposure (innate fear), but striking variation in long-lasting fear responses based on avoidance and risk assessment (learned fear), including automated stretch-attend posture quantification. TC entry (retention) latencies after foot shock differed >24 h and the re-explored TC area differed >50% among inbred mice. Next, we compared two closely related C57BL/6 substrains. Despite substantial individual differences, previously observed higher fear of C57BL/6N vs. C57BL/6J mice was reconfirmed, whereas fear extinction was fast and did not differ. The observed variation in fear expression in isogenic mice suggests individual differences in coping style with PTSD-like avoidance. Investigating the assumed epigenetic mechanisms, with reduced interpretational ambiguity and enhanced translational value in this assay, may help improve understanding of personality type-dependent susceptibility and resilience to neuropsychiatric disorders such as PTSD. [ABSTRACT FROM AUTHOR]

Developmental exposure to low dose of methylmercury (MeHg) has a long-lasting effect on memory and attention deficits in humans, as well as cognitive performance, depression-like behavior and the hippocampal levels of the brain-derived neurotrophic factor (Bdnf)in mice. The Bdnf receptor TrkB is a key player of Bdnf signaling. Using transgenic animals, here we analyzed the effect of the full-length TrkB overexpression (TK+) on behavior impairments induced by perinatal MeHg. TK overexpression in the MeHg-exposed mice enhanced generalized anxiety and cue memory in the fear conditioning (FC) test. Early exposure to MeHg induced deficits in reversal spatial memory in the Morris water maze (MWM) test and depression-like behavior in the forced swim test (FST) in only wild-type (WT) mice but did not affect these parameters in TK+ mice. These changes were associated with TK+ effect on the increase in Bdnf 2, 3, 4 and 6 transcription in the hippocampus as well as with interaction of TK+ and MeHg factors for Bdnf 1, 9a and truncated TrkB.T1 transcripts in the prefrontal cortex. However, the MeHginduced anxiety-like behavior in the elevated plus maze (EPM) and open field (OF) tests was ameliorated by TK+ background only in the OF test. Moreover, TK overexpression in the MeHg mice did not prevent significant stress-induced weight loss during the period of adaptation to individual housing in metabolic cages. These TK genotype-independent changes were primarily accompanied by the MeHg-induced hippocampal deficits in the activity-dependent Bdnf 1, 4 and 9a variants, TrkB.T1, and transcripts for important antioxidant enzymes glyoxalases Glo1 and Glo2 and glutathione reductase Gsr. Our data suggest a role of full-length TrkB in buffering against memory deficits and depression-like behavior in the MeHg mice but propose the involvement of additional pathways, such as the antioxidant system or TrkB.T1 signaling, in stress- or anxiety-related responses induced by developmental MeHg exposure. [ABSTRACT FROM AUTHOR]

Highlights: [•] We examined the effects of human contact on fear responses to people in shelter-housed dogs. [•] The three treatments were: control, human contact or human contact+toys. [•] Fear response was assessed by salivary cortisol and a human avoidance test. [•] Increased human contact reduced the fear response of the dogs in some circumstances. [•] Further research is required to fully determine the effects of human contact. [Copyright &y& Elsevier]

Maladaptive fear, such as fear that is persistent or easily generalized to a nonthreatening stimuli, is associated with anxiety-related disorders in humans. In the laboratory, maladaptive fear can be modeled in rodents using Pavlovian fear conditioning. Recently, an inbred mouse strain known as 129S1/SvImJ, or 129S1 have been reported as exhibiting impairments in fear extinction and enhanced fear generalization. With a long-term goal of identifying segregating genetic markers of maladaptive fear, we used Pavlovian fear conditioning to characterize a closely related substrain designated as 129S6/SvEvTac, or 129S6. Here we report that, like 129S1 animals, 129S6 mice exhibit appropriate levels of fear upon conditioning, but are unable to extinguish fear memories once they are consolidated. Importantly, the maladaptive fear phenotype in this inbred stain can be segregated by sub-strain when probed using conditioning protocols designed to assess generalized fear. We find that unlike the 129S1 substrain, mice from the 129S6 sub-strain do not generalize conditioned fear to previously novel contexts and can learn to discriminate between two similar contexts when trained using a discrimination protocol. These results suggest that at least two forms of maladaptive fear (deficits in fear extinction and fear generalization) can be can be functionally segregated, further suggesting that the underlying neurobiology is heritable. Given the observation that two closely related substrains can exhibit different constellations of maladaptive fear suggests that these findings could be exploited to facilitate the identification of candidate genes for anxiety-related disorders. [ABSTRACT FROM AUTHOR]

Highlights: [•] Many prospective army dogs fail the suitability test. [•] We compared owner judgements of early behaviour with test success. [•] Trainable dogs with low fear as young were more successful. [•] Dogs with hyperactivity problems as young rated better at test. [•] Owner ratings explained about 30% of variation in success. [ABSTRACT FROM AUTHOR]

Highlights: [•] Calves placed in an open arena perform locomotor play, which provides a time-efficient means of assessing playfulness. [•] Running and jumping by calves increases with age, and this is associated with increased exploration. [•] Effects of novelty on locomotor play are mediated by levels of exploratory behaviour, with calves showing more exploration doing more play. [•] Among younger calves, fear tends to reduce playfulness, but the effects are not strong. [ABSTRACT FROM AUTHOR]

Emotions such as fear in vertebrates are often strongly lateralised, that is, a single cerebral hemisphere tends to be dominant when processing emotive stimuli. Boldness is a measure of an individual's propensity to take risks and it has obvious connections with fear responses. Given the emotive nature of this well-studied personality trait, there is good reason to suspect that it is also likely to be expressed in a single hemisphere. Here, we examined the link between laterality and boldness in wild and captive-reared rainbowfish, Melanotaenia nigrans. We found that fish from the wild were bolder than those from captivity, which might be a reflection of the differences in the level of predation pressure experienced by the two populations. Secondly, we found that non-lateralised fish were bolder than strongly lateralised fish. In addition, differences in boldness scores between left- and right-biased fish were revealed. We suggest that variation in cerebral lateralisation contributes to the persistence of individual differences in boldness scores in animal populations. [ABSTRACT FROM AUTHOR]

The neurobiological mechanisms of emotional memory processing can be investigated using classical fear conditioning as a model system, and evidence from multiple lines of research suggests that sleep influences consolidation of emotional memory. In rodents, some of this evidence comes from a common finding that sleep deprivation from 0 to 6 h after fear conditioning training impairs processing of conditioned fear memory. Here, we show that during a 6-h session of sleep-wake (S-W) recording, immediately after a session of context-associated fear conditioning training, rats spent more time in wakefulness (W) and less time in slow-wave sleep (SWS) and rapid eye movement (REM) sleep. This context-associated fear conditioning training-induced reduction in SWS lasts for 2 h, and the REM sleep reduction lasts throughout the entire 6-h post-training S-W recording period. Interestingly, these reductions in SWS and REM sleep during this 6-h period did not impair memory consolidation for context-associated fear conditioning. The results of this study show, for the first time, that lesions within the dorsal part of the subcoeruleus nucleus (SubCD), which were unintentionally caused by the implantation of bipolar recording electrodes, impair consolidation of context-associated fear conditioning memory. Together, the results of these experiments suggest that emotional memory processing associated with fear conditioning can be completed successfully within less than a normal amount of sleep, but it requires a structurally and functionally intact SubCD, an area in the brain stem where phasic pontine wave (P-wave) generating cells are located. [ABSTRACT FROM AUTHOR]

Fear conditioning [inescapable shock training (ST)] and fearful context re-exposure (CR) alone can produce significant fear indicated by increased freezing and reductions in subsequent rapid eye movement (REM) sleep. Damage to or inactivation of the basolateral nucleus of the amygdala (BLA) prior to or after ST or prior to CR generally has been found to attenuate freezing in the shock training context. However, no one has examined the impact of BLA inactivation on fear-induced changes in sleep. Here, we used the GABA agonist, muscimol (MUS), to inactivate BLA prior to ST, the period when fear is learned, and assessed sleep after ST and sleep and freezing after two CR sessions. Wistar rats ( n = 14) were implanted with electrodes for recording sleep and with cannulae aimed bilaterally into BLA. After recovery, the animals were habituated to the injection procedure (handling) over 2 consecutive days and baseline sleep following handling was recorded. On experimental day 1, the rats were injected (0.5 μl) into BLA with either MUS (1.0 μM; n = 7) or vehicle (distilled water, n = 7) 30 min prior to ST (20 footshocks, 0.8 mA, 0.5-s duration, 60-s interstimulus interval). On experimental days 7 and 21, the animals experienced CR (CR1 and CR2, respectively) alone. Electroencephalogram and electromyogram were recorded for 8 h on each day, and the recording was scored for non-rapid eye movement sleep, REM sleep, and wakefulness. Freezing was examined during CR1 and CR2. MUS microinjections into BLA prior to ST blocked the post-training reduction in REM sleep seen in vehicle-treated rats. Furthermore, in MUS-treated rats, REM sleep after CR1 and CR2 was at baseline levels and freezing was significantly attenuated. Thus, BLA inactivation prior to ST blocks the effects of footshock stress on sleep and reduces fear memory, as indicated by the lack of freezing and changes in sleep after CR. These data indicate that BLA is an important regulator of stress-induced alterations in sleep and an important site for forming fear memories that can alter sleep. [ABSTRACT FROM AUTHOR]

Both human and animal research indicate that rapid eye movement sleep (REM) plays an important role in the processing of emotional information. REM is altered after fear conditioning in rats, but this alteration can be mitigated by exposure to a naïve conspecific. In addition, both the housing condition (isolated vs paired) and the experiences of rats' cagemates can influence the response to aversive events. Based on this prior work, the present study sought to determine the effects of social housing on the previously demonstrated impairment in the extinction of conditioned fear responses produced by REM deprivation. Rats were assigned to one of three housing conditions: housed with a naïve rat, housed with another fear-conditioned rat, or housed alone. The results demonstrated that rats housed with either a naïve or a fear-conditioned conspecific exhibited an impairment in the acquisition of extinction as a consequence of REM deprivation, as observed in previous studies. However, rats in the isolated condition demonstrated a trend toward an impairment only after continued extinction training. These results indicate that the effects of social housing on REM deprivation-induced impairments in learning and memory are subtle, but may explain some conflicting findings in the literature. [ABSTRACT FROM AUTHOR]

Abstract: Fear conditioning in animals has been used extensively to model clinical anxiety disorders. While individual animals exhibit marked differences in their propensity to undergo fear conditioning, the physiologically relevant mediators have not yet been fully characterized. Here, we demonstrate that C57BL/6 inbred mouse strain subjected to a regimen of chronic social defeat stress (CSDS) can be separated into susceptible and resistant subpopulations that display different levels of fear responses in an auditory fear conditioning paradigm. Susceptible mice had significantly more c-Fos protein expression in neurons of the basolateral amygdala (BLA) following CSDS and showed exaggerated conditioned fear responses, while there were no significant differences between groups in innate anxiety- and depressive-like behaviors. Through the use of conditional brain-derived neurotrophic factor (BDNF) knockout strategies, we find that elevated BLA BDNF level following fear conditioning training is a key mediator contributing to determine the levels of conditioned fear responses. Our results also show that relative to susceptible mice, resistant mice had a much faster recovery from conditioned stimuli-induced cardiovascular and corticosterone responses. Systemic administration of norepinephrine reuptake inhibitor atomoxetine increased c-Fos protein expression in BLA neurons following fear conditioning training and promoted the expression of conditioned fear in resistant mice. Conversely, administration of β-adrenergic receptor antagonist propranolol reduced fear conditioning training-induced c-Fos protein expression in BLA neurons and reduced conditioned fear responses in susceptible mice. These findings reveal a novel role for the BDNF signaling within the BLA in mediating individual differences in autonomic, neuroendocrine and behavioral reactivity to fear conditioning. [Copyright &y& Elsevier]

Abstract: The purposes of this study were to determine whether rearing with a broody hen influenced duration of tonic immobility, heterophil to lymphocyte ratio, and relative fluctuating asymmetry of chicks and to analyze the differences between broody and non-broody hens in fear and stress indicators. A total of 120 chicks (60 reared with a broody hen and 60 reared without a broody hen), and 48 hens (24 broody and 24 non-broody) were analyzed at 6 and 52 weeks of age, respectively. Broody hens were observed in 12 different Spanish breeds (Blue Andaluza, Black-barred Andaluza, Black Red Andaluza, Black Castellana, White-faced Spanish, Buff Prat, White Prat, Birchen Leonesa, Quail Castellana, Quail Silver Castellana, Red-barred Vasca, and Red Villafranquina), and all the chicks were from an F1 cross between the Black-barred Andaluza and the Black Castellana breeds. Tonic immobility duration was significantly longer (P <0.0001) in chicks reared without a broody hen than in those reared with a broody hen, suggesting that the presence of a broody hen reduces fear in chicks. There were no significant differences in the heterophil to lymphocyte ratio and the relative fluctuating asymmetry of leg length, leg width, and toe length, although the fluctuating asymmetry of wing length and the combined fluctuating asymmetry value of the 4 traits tended to be significant. These results suggest no effect on stress in chicks in the presence of a broody hen. Tonic immobility duration and heterophil to lymphocyte ratio were similar in broody and non-broody hens, indicating no association of broodiness with the fear and stress levels in hens. In conclusion, the presence of a broody hen during rearing has significant effects on fearfulness of chicks; rearing chicks with a mother being a method to reduce this major behavioral problem. However, broodiness was not associated with fear and stress indicators in hens. [Copyright &y& Elsevier]

Rationale: Contextual fear is evoked by re-exposing an animal to an environment that has been previously paired with an aversive or unpleasant stimulus. It can be assessed by freezing and cardiovascular changes such as increase in mean arterial pressure and heart rate. A marked increase in neuronal activity is associated with contextual fear conditioning, especially in limbic structures involved with defense reactions, such as the ventral portion of medial prefrontal cortex. Objective: Given the fact that transient receptor potential vanilloid type 1 (TRPV1) receptors could be involved in the expression of defensive behavior, the present work tested the hypothesis that TRPV1 manipulation in the ventromedial prefrontal cortex (vMPFC) modulates the expression of contextual conditioned fear. Methods: Male Wistar rats received bilateral microinjections into the vMPFC of the TRPV1 receptor antagonists capsazepine (1, 10, and 60 nmol/200 nL) or 6-iodonordihydrocapsaicin (3 nmol/200 nL), and the TRPV1 agonist capsaicin (1 nmol/200 nL) preceded by vehicle or 6-iodonordihydrocapsaicin before re-exposure to the experimental chamber for 10 min, 48 h after conditioning in two different protocols distinct by their aversiveness. Results: Both antagonists reduced the freezing and cardiovascular responses in the high aversive protocol. Capsaicin caused an increase in fear-associated responses that could be blocked by 6-iodonordihydrocapsaicin. Conclusions: Our results indicate that TRPV1 receptors located in the vMPFC have a tonic involvement in the modulation of the expression of contextual fear conditioning. [ABSTRACT FROM AUTHOR]

The quality of human contact that hens are exposed to will determine the degree of fear of humans that they experience. This has consequences for the welfare of commercial laying hens, as hens that are afraid of humans will be regularly exposed to a fear-provoking stressor. Hens can be habituated to human presence using positive or neutral human-animal interactions, although the specific human behaviours that are considered positive or neutral by the hens are still being determined. This experiment investigated whether the proximity or duration of visual contact with a human affected fear of humans in commercial caged laying hens (n = 216). Commercial laying hens were exposed to daily visual human contact at one of three proximities (0, 0.75 or 1.50 m) and one of three durations (2, 30 or 90 s) in a 3 by 3 factorial design for a period of 28 days. Avoidance behaviour was assessed on Days -5, 15 and 30, and the plasma corticosterone response to handling was assessed on Days -5 and Day 30. Visual contact with a stationary human at close proximity (0 m) significantly (P = 0.03) reduced the avoidance response of commercial laying hens to an approaching human, although there was no clear effect of proximity on corticosterone response to handling. The duration of human contact had no effect on avoidance behaviour or corticosterone response. Stockpeople may consider working more closely to the cages in a non-threatening manner to reduce fear of humans in their flock. The human-animal relationship has consequences for the welfare of laying hens by determining how stressful they find human contact. The present study manipulated the human-animal relationship in commercial caged laying hens, and determined that close proximity, but not duration, of visual human contact was effective in reducing the behavioural response of hens to human approach. Stockpeople may consider working more closely to the cages to reduce fear of humans in their flock. [ABSTRACT FROM AUTHOR]