Fear-related Behaviors Research Articles

Positive welfare effects of physical enrichments from the nature-, functions- and feeling- based approaches in farmed rainbow trout (Oncorhynchus mykiss)

The present study aimed to investigate whether environmental enrichment had significant effects on rainbow trout's welfare through nature-, functions- and feeling-based approaches. Fish group behavior was analyzed during the rearing phase, as well as growth performance and health status. We assessed individual's emotional reactivity through a novel-tank test by measuring fear-related behaviors and stress-related physiological responses. Fish boldness and neophobia were then evaluated towards a novel object. We showed that more complex environments decreased aggression levels and improved growth, without impacting fish immune status. Enriched fish were also found less fearful when isolated in a novel tank and bolder when facing a novel object. We concluded that complexifying the environment through the addition of physical structures which stimulate and encourage fish to explore promotes rainbow trout's welfare in farming conditions, according to the three different welfare approaches.

Implicit motives as the missing link between visionary leadership, approach and avoidance motivation, and vision pursuit

An unresolved question in visionary leadership research is, why must visions be high in imagery to cause affective reactions and be motivationally effective? Research in motivation psychology has shown that pictorial cues arouse implicit motives. Thus, pictorial cues from vision-induced imagery should arouse a follower’s implicit motives just like a real image. Hence, our fundamental proposition is that follower implicit motives and follower approach motivation serially mediate the relationship between leader vision and followers’ vision pursuit. We also examine the case of negative leader visions, with the central propositions that a negative leader vision arouses a follower’s implicit fear motives and that the follower’s implicit fear motives and follower avoidance motivation serially mediate the relationship between negative leader vision and the follower’s fear-related behaviors. Lastly, we assert that multiple implicit follower motives aroused by a multithematic leader vision exert additive as well as interaction effects on the follower’s vision pursuit. Plain Language Summary An unresolved question in leader vision research concerns why visions need to be high in imagery in order to elicit affective reactions in followers and be motivationally effective? Research in motivation psychology has shown that pictorial cues can arouse a person's implicit motives. It would thus be reasonable to expect that pictorial cues from leader vision-induced imagery arouse a follower's implicit motives just like a real image. Based on this reasoning, our key proposition is that follower implicit motives and follower approach motivation serially mediate the relationship between leader vision and followers' vision pursuit. We also integrate the special case of negative leader visions into our theorizing, with the central propositions that a negative leader vision arouses a follower's implicit fear motives, and that the follower's implicit fear motives and follower avoidance motivation serially mediate the relationship between negative leader vision and the follower's fear-related behaviors. Lastly, based on the distinction between mono- and multithematic visions, the latter of which with the potential to arouse more than one implicit motive simultaneously, we assert that multiple implicit follower motives aroused by a multithematic leader vision exert additive as well as interaction effects on the follower's vision pursuit.

Associations between Toxoplasma gondii infection and steroid hormone levels in spotted hyenas.

Toxoplasma gondii is a common parasite that infects warm-blooded animals and influences host physiology. T. gondii is known to target the host's central nervous system, affecting circulating levels of steroid hormones, fear-related behaviors, and health, although these effects appear to vary among host taxa. Here, we investigated the relationship between T. gondii infection and levels of plasma testosterone and cortisol within a wild population of spotted hyenas (Crocutacrocuta, n = 109). In our analyses, we accounted for age and sex via stratified regression analyses. We detected a negative association between circulating plasma testosterone and T. gondii infection among female cubs and subadults as well as adult male hyenas. We found no associations between T. gondii infection and cortisol in any age class or sex group of hyenas. Our work adds to a growing body of literature by characterizing the relationship between T. gondii infection and physiology in a novel host in its natural habitat. In a broader context, our findings indicate that responses to infection vary with characteristics of the host and point to a clear need for additional studies and priorities for future work that include diverse taxa and ecological settings.

Sexually Dimorphic Expression of Fear-conditioned Analgesia in Rats and Associated Alterations in the Endocannabinoid System in the Periaqueductal Grey

The endocannabinoid system within the periaqueductal grey (PAG) has been implicated in fear-conditioned analgesia (FCA), the profound suppression of pain upon re-exposure to a context previously paired with an aversive stimulus. Since the endocannabinoid and nociceptive systems exhibit sexual dimorphism, the aim of the present study was to assess possible sex differences in the expression of FCA, fear in the presence of nociceptive tone, and associated sex-dependent alterations in the endocannabinoid system within the PAG. Male and female Sprague-Dawley rats received footshock (10 × 1s; 0.4 mA; every 60 s) or no-footshock in a conditioning arena and 23.5 h later received intraplantar injection of formalin (2.5%) under brief isoflourane anaesthetic into the right hind paw. Nociceptive and fear-related behaviours were assessed 30 min later. Levels of endocannabinoids, N-acylethanolamines and neurotransmitters in the PAG were assessed by LC–MS/MS and expression of endocannabinoid system-related proteins by Western immunoblotting. Male, but not female, rats exhibited robust FCA and greater expression of fear-related behaviours than females. Fear-conditioned formalin-treated males, but not females, had higher levels of N-oleoylethanolamine (OEA) and γ-aminobutyric acid (GABA) in the PAG, compared with non-fear-conditioned controls. There was no effect of fear conditioning on the levels of FAAH or CB1 receptor expression (CB1R) in the PAG of male or female formalin-treated rats. Non-fear-conditioned females had higher levels of CB1R and PPARγ expression than non-fear-conditioned male counterparts. In summary, our results provide evidence of sexual dimorphism in the expression of FCA and fear-related behaviours, and associated alterations in components of the endocannabinoid system and GABA within the PAG.

Lack of affective priming indicates attitude-behaviour discrepancy for COVID-19 affiliated words

The ongoing novel coronavirus (COVID-19) pandemic has resulted in the enforcement of national public health safety measures including precautionary behaviours such as border closures, movement restrictions, total or partial lockdowns, social distancing, and face mask mandates in order to reduce the spread of this disease. The current study uses affective priming, an indirect behavioural measure of implicit attitude, to evaluate COVID-19 attitudes. Explicitly, participants rated their overall risk perception associated with contracting COVID-19 significantly lower compared to their perception of necessary precautions and overall adherence to public health measures. During baseline trials, participants explicitly rated COVID-19 affiliated words as unpleasant, similar to traditional unpleasant word stimuli. Despite rating the COVID-19 affiliated words as unpleasant, affective priming was not observed for congruent prime-target COVID-19 affiliated word pairs when compared to congruent prime-target pleasant and unpleasant words. Overall, these results provide quantitative evidence that COVID-19 affiliated words do not invoke the same implicit attitude response as traditional pleasant and unpleasant word stimuli, despite conscious explicit rating of the COVID-19 words as unpleasant. This reduction in unpleasant attitude towards COVID-19 related words may contribute towards decreased fear-related behaviours and increased incidences of risky-behaviour facilitating the movement of the virus.

Manipulating Memory Associations Minimizes Avoidance Behavior.

Memories of the past can guide humans to avoid harm. The logical consequence of this is if memories are changed, avoidance behavior should be affected. More than 80 years of false memory research has shown that people’s memory can be re-constructed or distorted by receiving suggestive false feedback. The current study examined whether manipulating people’s memories of learned associations would impact fear related behavior. A modified sensory preconditioning paradigm of fear learning was used. Critically, in a memory test after fear learning, participants received verbal false feedback to change their memory associations. After receiving the false feedback, participants’ beliefs and memories ratings for learned associations decreased significantly compared to the no feedback condition. Furthermore, in the false feedback condition, participants no longer showed avoidance to fear conditioned stimuli and relevant subjective fear ratings dropped significantly. Our results suggest that manipulating memory associations might minimize avoidance behavior in fear conditioning. These data also highlight the role of memory in higher order conditioning.

The effect of animal shelter sound on cat behaviour and welfare

AbstractThis study assessed how sound affected fear- and maintenance-related behaviour in singly housed cats (Felis silvestris catus) in an animal shelter. Two daily 30-min observation sessions (morning and evening) were made for 98 cats from admittance for ten days or until the cat was removed. Cat behaviour and presence of sound (classified by the source) were recorded by instantaneous and one-zero sampling with 15-s intervals. Each 30-min observation session was classified as ‘quiet’ or ‘noisy’ if the one-zero score for presence of sound was above or below the median of sessions at that time of day. To ensure that cats had at least two complete days of comparable observations, statistical analysis was restricted to the 70 cats (30 females, 40 males) present for two or more weekdays. Cats varied widely in the amount of fear and maintenance behaviour they performed. Males showed less fear and maintenance behaviour than females. Morning sessions consistently had much more sound than evenings, and cats showed more fear behaviour and less maintenance behaviour in the mornings. Cats showed more fear behaviour in noisy morning sessions than quiet ones, with no comparable difference in maintenance behaviour. Where sessions included a pronounced transition in sound, fear-related behaviour was more common after a transition from quiet to noisy and less common after a transition from noisy to quiet The results show that shelter cats vary greatly in their responses and suggest that sound in shelter environments can substantially affect their behaviour. Lowering sound levels in shelters may help improve cat welfare.

Comparative study on stress-induced hyperthermia, level of fear and behaviour of two genetically selected strains of domestic chicks to playback calls

Feed and alarm calls induce arousal in chicks, the former for feeding and the latter for danger. However, the response of birds genetically selected for meat or egg production to these calls have not been investigated. Thirty-six chicks each of the ISA Brown pullet and FUNAAB Alpha broiler (2 weeks old) were randomly allocated into three groups per strain and subjected to three playbacks: no call (NCP), feed call (FCP) and alarm call (ACP) continuously for 1 h. The test was carried out for 3 days/week for two weeks. The behaviours monitored were foraging, feeding, pecking (grouped as oral-related behaviour, ORB), freezing and clustering (grouped as fear-related behaviour, FRB). The eye (ET) and under wing (WT) temperatures were measured before and after each call and the change (ΔET and ΔWT) calculated. Tonic immobility (TI) test was performed after each call and the number of attempts to induce TI (NOATI) and the duration of TI (DTI) was recorded. Data on these two behavioural categories were subjected to General Linear Model analyses separately for each call having strain and day as fixed factors. The ΔET, ΔWT, NOATI and DTI were analyzed using Mann-Whitney U test. On both days, ΔET and ΔWT was similar after exposure to 1 h of FCP, ACP and NCP. FCP caused more (P < 0.001) ΔWT in pullet than broiler. Fear responses during FCP was not affected (P > 0.05) by day and strain. Strain × day interaction influenced (P < 0.05) only ORB, higher in the pullet on the 2nd day of FCP. Both strains showed similar ORB and FRB during FCP with ORB greater (P < 0.05) on the 2nd day. The ACP caused more (P < 0.05) ΔWT in broiler than pullet. Fear response to ACP was similar on both days. Although, DTI was similar for both strains, NOATI was greater (P < 0.001) in broiler than pullet. Interestingly, during NCP; ORB and FRB were similar on both days and for both strains. Although, fear response was similar on both days, DTI was greater (P < 0.05) in pullet than broiler. Finally, there was no significant (P > 0.05) strain × day or strain effects on ORB and FRB, with ORB greater (P < 0.05) on the 2nd day. In conclusion, pullet and broiler chicks showed greater arousal (higher ΔWT) to FCP and ACP, respectively. The pullets showed more fear responses during NCP and ACP than the broilers. The ORB and FRB were similar in both strains during each of the three calls.

Role of the Neuropeptide S System in Emotionality, Stress Responsiveness and Addiction-Like Behaviours in Rodents: Relevance to Stress-Related Disorders.

The neuropeptide S (NPS) and its receptor (NPSR1) have been extensively studied over the last two decades for their roles in locomotion, arousal/wakefulness and anxiety-related and fear-related behaviours in rodents. However, the possible implications of the NPS/NPSR1 system, especially those of the single nucleotide polymorphism (SNP) rs324981, in stress-related disorders and substance abuse in humans remain unclear. This is possibly due to the fact that preclinical and clinical research studies have remained separated, and a comprehensive description of the role of the NPS/NPSR1 system in stress-relevant and reward-relevant endpoints in humans and rodents is lacking. In this review, we describe the role of the NPS/NPSR1 system in emotionality, stress responsiveness and addiction-like behaviour in rodents. We also summarize the alterations in the NPS/NPSR1 system in individuals with stress-related disorders, as well as the impact of the SNP rs324981 on emotion, stress responses and neural activation in healthy individuals. Moreover, we discuss the therapeutic potential and possible caveats of targeting the NPS/NPSR1 system for the treatment of stress-related disorders. The primary goal of this review is to highlight the importance of studying some rodent behavioural readouts modulated by the NPS/NPSR1 system and relevant to stress-related disorders.

β-Arrestin-dependent ERK signaling reduces anxiety-like and conditioned fear-related behaviors in mice.

G protein-coupled receptors (GPCRs) are implicated in the regulation of fear and anxiety. GPCR signaling involves canonical G protein pathways but can also engage downstream kinases and effectors through scaffolding interactions mediated by β-arrestin. Here, we investigated whether β-arrestin signaling regulates anxiety-like and fear-related behavior in mice in response to activation of the GPCR δ-opioid receptor (δOR or DOR). Administration of β-arrestin-biased δOR agonists to male C57BL/6 mice revealed β-arrestin 2-dependent activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) in the dorsal hippocampus and amygdala and β-arrestin 1-dependent activation of ERK1/2 in the nucleus accumbens. In mice, β-arrestin-biased agonist treatment was associated with reduced anxiety-like and fear-related behaviors, with some overlapping and isoform-specific input. In contrast, applying a G protein-biased δOR agonist decreased ERK1/2 activity in all three regions as well as the dorsal striatum and was associated with increased fear-related behavior without effects on baseline anxiety. Our results indicate a complex picture of δOR neuromodulation in which β-arrestin 1- and 2-dependent ERK signaling in specific brain subregions suppresses behaviors associated with anxiety and fear and opposes the effects of G protein-biased signaling. Overall, our findings highlight the importance of noncanonical β-arrestin-dependent GPCR signaling in the regulation of these interrelated emotions.

Fear Extinction and Predictive Trait-Like Inter-Individual Differences in Rats Lacking the Serotonin Transporter.

Anxiety disorders are associated with a failure to sufficiently extinguish fear memories. The serotonergic system (5-hydroxytryptamine, 5-HT) with the 5-HT transporter (5-HTT, SERT) is strongly implicated in the regulation of anxiety and fear. In the present study, we examined the effects of SERT deficiency on fear extinction in a differential fear conditioning paradigm in male and female rats. Fear-related behavior displayed during acquisition, extinction, and recovery, was measured through quantification of immobility and alarm 22-kHz ultrasonic vocalizations (USV). Trait-like inter-individual differences in novelty-seeking, anxiety-related behavior, habituation learning, cognitive performance, and pain sensitivity were examined for their predictive value in forecasting fear extinction. Our results show that SERT deficiency strongly affected the emission of 22-kHz USV during differential fear conditioning. During acquisition, extinction, and recovery, SERT deficiency consistently led to a reduction in 22-kHz USV emission. While SERT deficiency did not affect immobility during acquisition, genotype differences started to emerge during extinction, and during recovery rats lacking SERT showed higher levels of immobility than wildtype littermate controls. Recovery was reflected in increased levels of immobility but not 22-kHz USV emission. Prominent sex differences were evident. Among several measures for trait-like inter-individual differences, anxiety-related behavior had the best predictive quality.

Paradoxical changes in mood-related behaviors on continuous social isolation after weaning

Continuous social isolation (SI) from an early developmental stage may have different effects in youth and adulthood. Moreover, SI is reported to impair neuronal plasticity. In this study, we used post-weaning rats to compare the impact of continuous SI on depressive-like, anxiety-related, and fear-related behaviors and neuronal plasticity in puberty and adulthood. Furthermore, we assessed the effect of lithium on behavioral changes and neuronal plasticity. Continuous SI after weaning induced depressive-like behaviors in puberty; however, in adulthood, depressive-like and anxiety-related behaviors did not increase, but—paradoxically—decreased in comparison with the controls. The decreased expression of neuronal plasticity-related proteins in the hippocampus in puberty was more prominent in the prefrontal cortex and hippocampus in adulthood. In contrast, SI after weaning tended to decrease fear-related behaviors in puberty, a decrease which was more prominent in adulthood with increased neuronal plasticity-related protein expression in the amygdala. Lithium administration over the last 14 days of the SI-induced period removed the behavioral and expression changes of neuronal plasticity-related proteins observed in puberty and adulthood. Our findings suggest that the extension of the duration of SI from an early developmental stage does not simply worsen depressive-like behaviors; rather, it induces a behavior linked to neuronal plasticity damage. Lithium may improve behavioral changes in puberty and adulthood by reversing damage to neuronal plasticity. The mechanisms underlying the depressive-like and anxiety-related behaviors may differ from those underlying fear-related behaviors.

Medial or lateral orbitofrontal cortex activation during fear extinction differentially regulates fear renewal

Some anxiety-related disorders, such as panic disorder, specific phobia, post-traumatic stress disorder (PTSD), and obsessive-compulsive disorder (OCD), develop because of the poor regulation and inappropriate expression of fear-related behavior at the wrong place and wrong time. In clinical settings, exposure therapy, which consists of repeated presentation of trauma-related stimuli without real threats in the therapeutic context, is commonly used to treat these disorders. However, 30–50 % of patients suffer from the recurrence of anxiety symptoms after they leave the therapeutic context. This behavioral phenomenon is called renewal. In this study, ABA Pavlovian fear renewal paradigm was used to assess the role of the aberrant orbitofrontal cortex (OFC) activation, a symptom of OCD patients, on fear regulation in laboratory settings. The rats were fear conditioned in one context (context A), extinguished to the tones in another context (context B), and then tested in either context A or B. During extinction, rats were subjected to lateral or medial OFC activation. We found that rats that underwent extinction with either lateral or medial OFC activation were unable to use the context to determine whether it was a safe or dangerous context during renewal test. Interestingly, the rats with lateral OFC activation during extinction showed generally high fear, whereas the rats with medial OFC activation during extinction showed generally low fear. In conclusion, our results suggested that aberrant activation of specifically the lateral OFC may have a negative impact during exposure therapy treatments and results in their poor regulation of fear-related behavior.

Exploratory drive, fear, and anxiety are dissociable and independent components in foraging mice

Anxiety-like behavior of rodents is frequently accompanied by reduced exploration. Here, we identify dissociable components of anxiety, fear, and exploratory drive of sated and foraging mice. With the help of behavioral assays, including the open field task, elevated plus maze, dark–light transition task, and beetle mania task, we demonstrate a general increase in exploration by food restriction. Food-restricted mice bred for high anxiety behavior (HAB) showed ameliorated anxiety- but not fear-related behavior. By means of principal component analysis, we identified three independent components, which resemble the behavioral dimensions proposed by Gray’s Reinforcement Sensitivity Theory (approach behavior, avoidance behavior, and decision making). Taken together, we demonstrate anxiolytic consequences of food restriction in a mouse model of anxiety disorders that can be dissociated from a general increase in foraging behavior.

Apical intercalated cell cluster: A distinct sensory regulator in the amygdala.

GABAergic neurons regulate different aspects of information processing in the amygdala. Among these are clusters of intercalated cells (ITCs), which have been implicated in fear-related behaviors. Although a few of the ITC clusters have been studied, the functional role of apical ITCs (apITCs) is unknown. Here, we combine monosynaptic rabies tracing with optogenetics and demonstrate that apITCs receive synaptic input from medial geniculate nucleus (MGm), posterior intralaminar nucleus (PIN), and medial dorsal nucleus of the thalamus and from a diverse range of cortical areas including temporal association, entorhinal, insular, piriform, and somatosensory cortex. Upon fear learning, PIN/MGm inputs are strengthened, indicative of their involvement in fear behaviors. 3-D reconstruction of apITCs reveals local arborization and innervation of the dorsal striatum and lateral amygdala. We further show that apITCs provide sensory feedforward inhibition to LA principal cells, a putative mechanism for controlling plasticity during fear learning.

Central amygdala angiotensin type 1 receptor (AT 1 R) expressing neurons influence fear extinction

Background The renin-angiotensin system (RAS) has been implicated in stress-related disorders (ie., PTSD), however the mechanisms responsible for this connection and the therapeutic potential for targeting the RAS in PTSD remains unknown. Using angiotensin receptor transgenic mice combined with neuroanatomical, behavioral and electrophysiological approaches we examined the role of central amygdala expressing angiotensin II type 1 receptors (AT1R) in fear-related behavior. Methods Dual immunohistochemistry and whole-cell patch-clamp recording were used to characterize AT1R-eGFP+ cells in the amygdala of the AT1R-eGFP reporter mouse. Retrograde labeling was employed to detect the connectivity between the AT1R-eGFP cells and other brain regions. Pavlovian fear conditioning and cre-expressing lentivirus (LV) injection were used to demonstrate the effects of AT1R deletion on fear memory in AT1R-floxed mice. Results AT1R-eGFP+ neurons in the amygdala were predominantly expressed in the lateral division of the central amygdala (CeL), with little AT1R-eGFP expression in the basolateral amygdala, basomedial amygdala, medial amygdala or medial division of the central amygdala. Characterization of AT1R-eGFP+ neurons in the CeL demonstrated that the AT1R mainly expressed in GABAergic neurons (99%). Activation of the receptor with angiotensin II can facilitate GABAergic inhibition in the CeL. AT1R was deleted via inject cre-expressing lentivirus into the central amygdala (CeA) of AT1R-Floxed mice. CeA AT1R knockdown did not affect fear acquisition, but enhanced the extinction of fear as shown by reduced percent freezing during extinction training (57.04% ± 3.9 LV-GFP v.s. 42.6% ± 4.1 LV-Cre group, p<0.05, n=12 and retention tests (53.5% ± 5.3 LV-GFP v.s. 34.4% ± 5.3 LV-Cre group, p<0.05, n=13). Furthermore, retrograde labeling revealed that some of the AT1R-eGFP+ neurons project to the ventral tegmental area (VTA), an important brain structure to initiate the fear extinction. Conclusion These findings provide evidence for a novel CeL cell type and suggest CeL AT1R-expressing neurons play a role in fear extinction. Future studies are needed to further characterize underlying neurocircuits that likely interact with amygdala expressing AT1R neurons.

Evaluation of a Brain Angiotensinergic Circuit in Fear-Related Behavior

The renin-angiotensin system (RAS) has been implicated in post-traumatic stress disorder (PTSD). Here we examined components of the brain RAS, in particular the origin of brain angiotensinogen (AGT), angiotensin II type 1 receptor (AT1R) and their functional role in fear-related behavior.

Evaluation of a Brain Angiotensinergic Circuit in Fear-Related Behavior

The renin-angiotensin system (RAS) has been implicated in post-traumatic stress disorder (PTSD). Here we examined components of the brain RAS, in particular the origin of brain angiotensinogen (AGT), angiotensin II type 1 receptor (AT1R) and their functional role in fear-related behavior.

Socialization in Commercial Breeding Kennels: The Use of Novel Stimuli to Measure Social and Non-Social Fear in Dogs.

Simple SummaryOwner-based reports of dogs presumed to come from commercial breeding kennels (CBKs) suggest high levels of fear in this population. Fear in kenneled dogs is a serious behavioral welfare concern as it may lead to both acute and chronic stress. Novel social and non-social stimuli have been shown to elicit behaviors associated with fear in animals. New knowledge on the levels of fear in dogs from CBKs could be used to further refine protocols intended for assessment of welfare in CBKs and to improve breeders’ management practices. The aim of this study, therefore, was to evaluate how dogs from CBKs reacted to social (i.e., a person approaching) and non-social (i.e., a traffic cone and a dog statue) stimuli, and to perform a preliminary evaluation of how these responses might be used as indicators of dogs’ overall socialization levels in kennels. Results revealed that dogs had primarily mildly fearful responses to the stimuli presented. These findings are encouraging as extreme fearful reactions were rarely recorded. Nevertheless, there is a clear margin for commercial breeders to improve the socialization protocols in their kennels to better incorporate both social and non-social stimuli.Understanding the behavioral welfare of dogs in commercial breeding kennels (CBKs) is important for improving breeders’ management practices as well as dog welfare. In the current study, breeding dogs from CBKs were exposed to novel stimuli to evaluate their behavioral responses, with emphasis on indicators of fear. Subjects were presented with a standard stranger-approach test, a traffic cone, and a realistic dog statue. Sixty dogs were exposed to the three stimuli and behavioral responses were scored using an ethogram developed for this study. Dogs spent significantly more time investigating the environment, staying further away from the stimulus, and they took longer to approach and investigate when presented with the cone than with the dog statue or stranger (p < 0.01). These findings suggest that the cone elicited more fear-related behaviors than the dog statue and stranger. Given these results, in addition to socializing their dogs to unfamiliar people and other dogs within their kennels, commercial breeders should be encouraged to increase the exposure of their dogs to more diverse novel stimuli to reduce non-social fear and support the welfare of dogs while they reside in the kennel and when they transition to new homes.

Role of Medial Prefrontal Cortical Neurons and Oxytocin Modulation in the Establishment of Social Buffering.

Fear-related behaviors are rigidly controlled by the medial prefrontal cortex (mPFC). The mPFC is activated by the prosocial hormone oxytocin, which plays an important role in social buffering. We used a slice patch current-clamp recording in single- and pair-exposed rats who were subjected to electric shocks, to determine the cellular mechanism of the action of oxytocin in the mPFC under social buffering conditions. Pair-exposed rats showed a significant reduction in both freezing and passive avoidance behaviors compared to single-exposed rats. It was observed that input resistance in pyramidal neurons decreased in both single- and pair-exposed rats than na?ve rats, but input resistance in interneurons increased in pair-exposed rats than single-exposed rats. We found that the number of action potential (AP) spikes in the mPFC pyramidal neurons decreased significantly in pair-exposed rats than in single-exposed rats. The pyramidal neurons in the mPFC were similarly regulated by oxytocin in singleand pair-exposed rats, while the number of AP spikes in interneurons by oxytocin decreased in single-exposed rats, but there was no significant change in pair-exposed rats. Therefore, our findings reveal that a decrease in mPFC pyramidal neuronal activity in pair-exposed rats through social interaction induces a reduction in fear-related behavior via obstruction of fear-memory formation; however, no such reduction was observed in single-exposed rats. Moreover, we suggest that the oxytocin-mediated decrease in neuronal activity in the mPFC could facilitate social buffering.