Fearful Expressions Research Articles

Extinction training suppresses activity of fear memory ensembles across the hippocampus and alters transcriptomes of fear-encoding cells.

Contextual fear conditioning has been shown to activate a set of "fear ensemble" cells in the hippocampal dentate gyrus (DG) whose reactivation is necessary and sufficient for expression of contextual fear. We previously demonstrated that extinction learning suppresses reactivation of these fear ensemble cells and activates a competing set of DG cells-the "extinction ensemble." Here, we tested whether extinction was sufficient to suppress reactivation in other regions and used single nucleus RNA sequencing (snRNA-seq) of cells in the dorsal dentate gyrus to examine how extinction affects the transcriptomic activity of fear ensemble and fear recall-activated cells. Our results confirm the suppressive effects of extinction in the dorsal and ventral dentate gyrus and demonstrate that this same effect extends to fear ensemble cells located in the dorsal CA1. Interestingly, the extinction-induced suppression of fear ensemble activity was not detected in ventral CA1. Our snRNA-seq analysis demonstrates that extinction training markedly changes transcription patterns in fear ensemble cells and that cells activated during recall of fear and recall of extinction have distinct transcriptomic profiles. Together, our results indicate that extinction training suppresses a broad portion of the fear ensemble in the hippocampus, and this suppression is accompanied by changes in the transcriptomes of fear ensemble cells and the emergence of a transcriptionally unique extinction ensemble.

Category-dependent contribution of dog facial and bodily cues in human perception of dog emotions

The increasing popularity of human-dog interaction in our society calls for fuller understanding of humans’ ability to appraise dogs’ affective states, yet most research only focuses on recognizing dog facial expressions of primary/basic emotions. While the face is the dominant human emotional expression channel, bodily cues are also informative indicators of dog emotional states. In this online study, with dynamic and naturalistic videos depicting a common range of dog primary (anger, disgust, fear, happiness, sadness, surprise) and secondary emotions (appeasement, frustration, pain, positive anticipation, separation-distress), we compared human performance from 447 participants in categorizing dog facial expressions (with a visible dog face only) and bodily expressions (with a visible dog face and body). The analysis revealed when averaging across all tested emotions, bodily expression tended to attract higher categorization accuracy than facial expression. However, the two expression channels demonstrated category-dependent modification of dog emotion categorization accuracy (e.g., higher accuracy in recognizing facial expressions of anger and surprise, but bodily expressions of happiness and fear) and bias (e.g., mistaking fear facial expression as happiness, but fear bodily expression as sadness). Furthermore, the impact of owner experience on recognizing dog emotions was also modulated by the expression channel and emotion category (e.g., prolonged experience with dogs tended to improve performance in recognizing the fear facial expression, and the appeasement bodily expression). Taken together, these results suggest that different channels of emotional expression by dogs may transmit category-specific diagnostic emotional cues, which aid human appraisal of their affective states.

Time-dependent neural arbitration between cue associative and episodic fear memories.

After traumatic events, simple cue-threat associative memories strengthen while episodic memories become incoherent. However, how the brain prioritises cue associations over episodic coding of traumatic events remains unclear. Here, we developed an original episodic threat conditioning paradigm in which participants concurrently form two memory representations: cue associations and episodic cue sequence. We discovered that these two distinct memories compete for physiological fear expression, reorganising overnight from an overgeneralised cue-based to a precise sequence-based expression. With multivariate fMRI, we track inter-area communication of the memory representations to reveal that a rebalancing between hippocampal- and prefrontal control of the fear regulatory circuit governs this memory maturation. Critically, this overnight re-organisation is altered with heightened trait anxiety. Together, we show the brain prioritises generalisable associative memories under recent traumatic stress but resorts to selective episodic memories 24 h later. Time-dependent memory competition mayprovide a unifying account for memory dysfunctions in post-traumatic stress disorders.

Orexin mechanisms in the prelimbic cortex modulate the expression of contextual conditioned fear.

Despite the existing anatomical and physiological evidence pointing to the involvement of orexinergic projections from the lateral hypothalamus (LH) in regulating fear-related responses, little is known regarding the contribution of the orexin system in the prelimbic cortex (PL) on contextual fear. We investigated the role of orexin-A (OrxA) and orexin type 1 receptors (Orx1R) in the PL during the expression of contextual conditioned fear in mice. Neural tract tracing of the LH-PL pathway and Orx1R immunoreactivity in the PL of C57BL/6 male mice were performed. In a pharmacological approach, the animals were treated with either the Orx1R selective antagonist SB 334,867 (3, 30, and 300 nM/0.1 µL) or OrxA (28, 70, and 140 pmol/0.1 µL) in the PL before the test session of contextual fear conditioning. Neural tract tracing deposits in the LH showed some perikarya, mainly axons and terminal buttons in the PL, suggesting LH-PL reciprocate pathways. Furthermore, we showed a profuse network comprised of Orx1R-labeled thin varicose fibers widely distributed in the same field of LH-PL pathways projection. The selective blockade of Orx1R with SB 334,867 at 30 and 300 nM in the PL caused a decrease in freezing response, whereas the treatment with OrxA at 140 pmol promoted an increase in freezing response. In summary, these data confirmed an anatomical link between LH and PL, established the presence of Orx1R in the PL, and a modulatory role of the orexin system in such structure, possibly mainly via Orx1R, during contextual fear conditioning.

Perceptual sensitivity to labeling stereotyped emotion expressions: Associations with age and subclinical psychopathology symptoms from childhood through early adulthood.

This study investigates (a) age-related differences in how the intensity of stereotyped facial expressions influence the emotion label children, adolescents, and adults assign to that face and (b) how this perceptual sensitivity relates to subclinical symptoms of psychopathology. In 2015-2016, 184 participants aged 4-25 years viewed posed stereotypes of angry, fearful, sad, and happy expressions morphed with neutral expressions at 10%-90% intensity. Thin plate regression smoothing splines were used to chart nonlinear associations between age and the perceptual threshold participants needed to assign the emotion label expected based on cultural consensus. Results suggest that sensitivity to labeling stereotypical happy faces as "happy" peaked by age 4. Sensitivity to perceiving stereotypical angry faces as "angry" increased from ages 4 to 7 and then plateaued. In contrast, sensitivity to perceiving stereotypical fearful and sad faces demonstrated protracted development, not reaching a plateau until ages 15 and 16, respectively. Reduction in selecting the "I don't know" response was the primary driver of these age-related changes. Stereotyped fear expressions required the highest intensity to be labeled as such and showed the most marked change in perceptual threshold across development. Interestingly, lower intensity morphs of stereotypical fear faces were frequently labeled "sad." Furthermore, perceiving lower intensity fear morphs was associated with fewer internalizing and externalizing symptoms in participants aged 7-19. This study describes the development of perceptual sensitivity to labeling stereotypical expressions of emotion according to cultural consensus and shows that how people perceive and categorize ambiguous facial expressions is associated with vulnerability to psychopathology. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Sex differences in fear expression and persistence in an animal model of Post-Traumatic Stress Disorder

Post-Traumatic Stress Disorder (PTSD) is a complex psychiatric condition arising from traumatic experiences, marked by abnormal fear memories. Despite women are twice as likely as men to develop PTSD, the biological mechanisms underlying this disparity remain inadequately explored, particularly in preclinical studies involving female subjects.Previous research shows that female rats exhibit active fear responses, while males display passive behaviors. Additionally, sex differences in ultrasonic vocalizations (USVs) during fear conditioning have been observed, indicating varying emotional responses.Here, we validated a traumatic stress model consisting of footshock exposure paired with social isolation − originally developed in male rats − on females for the first time, focusing on sex differences in fear memory expression, retention and extinction. Our findings reveal that only during trauma exposure, males predominantly exhibited passive responses, whereas females demonstrated more active responses, despite both sexes emitting similar numbers of alarm USVs. Females also showed lower levels of freezing and USV emissions throughout extinction sessions and displayed a higher extinction rate compared to males. Notably, only males displayed a conditioned fear response when triggered by a single mild stressor.These findings highlight sex differences in trauma responses and fear memory processes. The study emphasizes the importance of incorporating 22-kHz USV evaluations along with other behavioral metrics for a comprehensive understanding of fear memory. This research contributes to the existing literature on traumatic stress models as well as underscores the necessity of including female subjects in preclinical studies to better inform treatment and prevention strategies tailored to both sexes.

Emotional scenes as context in emotional expression recognition: The role of emotion or valence match.

Emotion recognition is influenced by contextual information such as social category cues or background scenes. However, past studies yielded mixed findings regarding whether broad valence or specific emotion matches drive context effects and how multiple sources of contextual information may influence emotion recognition. To address these questions, participants were asked to categorize expressions on male and female faces posing happiness and anger and happiness and fear on pleasant and fearful backgrounds (Experiment 1, conducted in 2019), fearful and disgusted expressions on fear and disgust eliciting backgrounds (Experiment 2, conducted in 2022), and fearful and sad expressions on fear and sadness eliciting backgrounds (Experiment 3, conducted in 2022). In Experiment 1 (where stimuli varied in valence), a broad valence match effect was observed. Faster recognition of happiness than fear and anger was more pronounced in pleasant compared to fearful scenes. In Experiments 2 and 3 (where stimuli were negative in valence), specific emotion match effects were observed. Faster recognition occurred when expression and background were emotionally congruent. In Experiments 1 and 3, poser sex independently moderated emotional expression recognition speed. These results suggest that the effect of emotional scenes on facial emotion recognition is mediated by a match in valence when broad valence is task-relevant. Specific emotion matches drive context effects when participants categorize expressions of a single valence. Looking at the influence of background contexts and poser sex together suggests that these two sources of contextual information have an independent rather than an interactive influence on emotional expression recognition speed. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Psychological impact of physical distancing due to covid 19 pandemic on school and higher education students

MoHFW India, WHO, NHS, and CDC suggested imposing lockdown and closing educational institutions with the spread of covid 19 pandemic to reduce the risk of transmitting the disease. Students faced negative mental health symptoms due to unexpected transition from physical to virtual learning, increased screen time, physical distancing, altered habits, rumors through news, print media, social media, and other means. This study focuses on the psychological impact of covid 19 on school and higher education students due to psychosocial factors like physical distancing. 2140 students, mixed gender, in age from 17 years to 25 years (M = 22.73, SD = 6.12) are selected as sample population for the study. Mixed-method approach is used for data collection that include face to face interactions in clinics, Health Questionnaires & Self-Reports, online counseling to assess the stress & depression, Generalized Anxiety Disorder-7, rating scales for Behavior analysis, Warwick-Edinburgh Mental Well-being Scale to assess perceived stress, depression, anxiety, and mental health & well-being, respectively. Analysis of data shows that 42.7% of school and higher education students have either depression or anxiety. 71.7% of students reported poor health and well-being. 36.7% of students reported fear of getting infected by virus, many students were reported with cognitive dissonance in myths and truths about Covid-19. 37.9% of students spend their time on media & social media, including watching TV or reading Covid-19 related news and information on various platforms. About 56.2% students reported with increased use of social media. There was a minor difference between depression and anxiety, as reported by females and male students, however expression of separation fear was slightly higher in male students than female students. Physical distancing and lack of social interaction caused stress, anxiety (GAD) and depression symptoms in students due to imbalances in hormones & neurotransmitters.

Prophylactic (R,S)-ketamine and (2S,6S)-HNK decrease fear expression by differentially modulating fear neural ensembles

We previously reported that a single injection of (R,S)-ketamine or its metabolite (2S,6S)-hydroxynorketamine (HNK) prior to stress attenuates learned fear. However, whether these drugs attenuate learned fear through divergent or convergent effects on neural activity remains to be determined. 129S6/SvEv male mice were injected with saline, (R,S)-ketamine, or (2S,6S)-HNK one week before a 3-shock contextual fear conditioning (CFC) paradigm. Five days later, mice were re-exposed to the aversive context, and euthanized one hour later to quantify active cells. Brains were processed for c-fos immunoreactivity, and neural networks were built with a novel, wide-scale imaging pipeline. We found that (R,S)-ketamine and (2S,6S)-HNK attenuate learned fear. Fear-related neural activity was altered in: dorsal CA3 following (2S,6S)-HNK; ventral CA3 and CA1, infralimbic (IL) and prelimbic (PL) regions, insular cortex (IC), retrosplenial cortex (RSP), piriform cortex (PIR), nucleus reuniens (RE), and periaqueductal grey (PAG) following both (R,S)-ketamine and (2S,6S)-HNK; and in the paraventricular nucleus of thalamus (PVT) following (R,S)-ketamine. Dorsal CA3 and ventral hippocampus activation correlated with freezing in the (R,S)-ketamine group, and RSP activation correlated with freezing in both (R,S)-ketamine and (2S,6S)-HNK groups. (R,S)-ketamine increased connectivity between cortical and subcortical regions while (2S,6S)-HNK increased connectivity within these regions. This work identifies novel nodes in fear networks, involving the RE, PIR, IC, PAG and RSP, that can be targeted with neuromodulatory strategies or pharmaceutical compounds to treat fear-induced disorders. This approach could be used to optimize target engagement and dosing strategies of existing medications.

Impaired facial emotion recognition in individuals with bipolar disorder

BackgroundIndividuals with bipolar disorder (BD) often struggle with emotional regulation and social interactions, partly due to difficulties in accurately recognizing facial emotions. MethodsFrom September 2021 to February 2023, 69 BD individuals-comprising 23 with bipolar manic/hypomanic episode (BME), 23 with bipolar depressive episode (BDE), 23 with bipolar euthymic (EUT)-and 23 healthy controls (HCs) were enrolled. Diagnosis adhered to DSM-IV criteria using M.I.N.I 5.0, alongside assessments via Hamilton Depression Scale 17 and Young Manic Rating Scale. Recognition tasks involving 84 facial expression images across six categories. The Wilcoxon rank-sum test compares two groups, while the Kruskal-Wallis test compares multiple groups with subsequent adjusted pairwise comparisons. ResultsThe overall correct recognition rate of facial expressions in the BD group (79 %) was significantly lower than that of the HC group (83 %) (P=0.004). Primary differences were noted in neutral (93 % vs. 100 %, P=0.012) and fear (79 % vs. 86 %, P=0.023) expressions. Within the BD group, correct recognition rates were 71 % for BME, 80 % for BDE, and 80 % for EUT, all lower than in the HC group. Significant differences in correct recognition rates of neutral, fear, and joy expressions were observed among the four groups (P<0.05), with the BME group exhibiting the lowest rate. Misidentification of facial expressions was more frequent in the BD group compared to the HC group, particularly among negative expressions. ConclusionPatients with BD demonstrate lower correct recognition and higher misidentification rates of facial expressions, with those experiencing manic episodes showing impaired recognition of neutral, joy, and fear expressions.

Analysis of Multimodality, Critical Discourse, and Translation Strategy "Buto Had a Toothache"

The purpose of this article is to analyze the multimodality aspects involved in the translation of story books for children and the translation strategy that is used from Indonesian into English. In addition to the multimodality aspect reviewed, this article also analyzes the translated text using critical discourse analysis to determine the acceptability of the target text. This research uses a descriptive qualitative method. Based on the analysis of the translation of this illustrated story, it was found that from a multimodality point of view, expressions of anger, sadness, irritation, and fear are depicted by the difference in the eyes and the shape of the lips in this story. Thus, the reader gets a clear meaning from the illustrations depicted apart from the narrative conveyed in the story. Judging from the results of the translation strategy, 16% of the story is translated using compression, 25% using literal, and 59% of the story is translated using expansion so that the meaning and essence of the story are still conveyed properly.

Two sides of the same coin? What neural processing of emotion and rewards can tell us about complex post-traumatic stress disorder and borderline personality disorder

BackgroundBorderline personality disorder (BPD) and complex posttraumatic stress disorder (cPTSD) share clinical similarities, complicating diagnosis and treatment. Research on the neurobiology of BPD and monotraumatic PTSD has shown that a prefrontal-limbic imbalance in emotional and reward processing is a hallmark of both disorders, but studies examining this network in cPTSD are lacking. Therefore, this study aimed to directly compare neural processing of emotion and reward during decision making in cPTSD and BPD. MethodsUsing functional magnetic resonance imaging, we measured neural activity in female patients (27 patients with cPTSD, 21 patients with BPD and 37 healthy controls) during a Desire-Reason Dilemma task featuring distracting fearful facial expressions. ResultsWe found no differences in neural activation when comparing cPTSD and BPD. However, when grouping patients based on symptom severity instead on diagnosis, we found that increased symptoms of cPTSD were associated with increased activation of dorsolateral prefrontal cortex during reward rejection, whereas increased symptoms of BPD were associated with decreased activation in prefrontal and limbic regions during reward rejection with distracting negative emotional stimuli. ConclusionThis is the first study to investigate and compare emotional processing and reward-based decision making in cPTSD and BPD. Although we found no neural differences between disorders, we identified symptom-related neural patterns. Specifically, we found that elevated cPTSD symptoms were related to greater sensitivity to reward stimuli, whereas heightened BPD symptoms were related to increased susceptibility to emotional stimuli during goal-directed decision making. These findings enhance our understanding of neural pathomechanisms in trauma-related disorders.

Sex differences in contextual fear expression are associated with altered medial prefrontal cortex activity.

Understanding the neural basis of fear expression in rodents has implications for understanding pathological fear responses that characterize posttraumatic stress disorder. Even though posttraumatic stress disorder is more common in females, little is known about the neural circuit interactions supporting fear expression in female rodents. In this study, we were interested in determining whether neural activity associated with the expression of contextual fear differed between males and females within the projections from the medial prefrontal cortex to the ventrolateral periaqueductal gray, and in the medial prefrontal cortex in neurons that do not project to the periaqueductal gray. We infused a viral retrograde tracer into the ventrolateral periaqueductal gray in male and female rats and trained them in a contextual fear conditioning task. The following day rats were re-exposed to the conditioning context and were sacrificed shortly thereafter. Neural activity was measured using EGR1 immunofluorescence. The behavioral results showed that males exhibited higher levels of freezing during the context test than females. Male rats that underwent training and testing showed an increase in the proportion of viral infected cells that express EGR1 in the PL compared to rats that had only received context exposure. Trained female rats were not different than controls, however a direct comparison between sexes was not different. In cells not labeled by the tracer, males showed higher levels of fear-induced EGR1 expression in the prelimbic cortex than females. Conversely, females showed higher levels of EGR1 expression in the infralimbic cortex following testing as compared to males. These results suggest that sex differences in the expression of contextual fear may involve differences in the relative activity levels of the prelimbic and infralimbic cortex.

Improved Histogram of Oriented Gradient (HOG) Feature Extraction for Facial Expressions Classification

Facial expression classification system is one of the implementations of machine learning (ML) that takes facial expression datasets, undergoes training, and then utilizes the trained results to recognize facial expressions in new facial images. The recognized facial expressions include anger, contempt, disgust, fear, happy, sadness, and surprise expressions. The method employed for facial feature extraction utilizes histogram-oriented gradient (HOG). This study proposes an enhancement method for HOG feature extraction by reducing the feature dimension into multiple sub-features based on gradient orientation intervals, referred to as HOG channel (HOG-C). Classifier testing techniques are divided into two methods for comparison—support vector machines (SVM) with HOG features and SVM with HOG-C features. The testing results demonstrate that SVM with HOG achieves an accuracy of 99.9% with an average training time of 18.03 minutes, while SVM with HOG-C attains a 100% accuracy with an average training time of 18.09 minutes. The testing outcomes reveal that the implementation of SVM with HOG-C successfully enhances accuracy for facial expression classification.

GluN2B on Adult-Born Granule Cells Modulates (R,S)-Ketamine's Rapid-Acting Effects in Mice.

Standard antidepressant treatments often take weeks to reach efficacy and are ineffective for many patients. (R,S)-ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, has been shown to be a rapid-acting antidepressant and to decrease depressive symptoms within hours of administration. While previous studies have shown the importance of the GluN2B subunit of the NMDA receptor on interneurons in the medial prefrontal cortex, no study to our knowledge has investigated the influence of GluN2B-expressing adult-born granule cells. Here, we examined whether (R,S)-ketamine's efficacy depends on adult-born hippocampal neurons using a genetic strategy to selectively ablate the GluN2B subunit of the NMDA receptor from Nestin+ cells in male and female mice, tested across an array of standard behavioral assays. We report that in male mice, GluN2B expression on 6-week-old adult-born neurons is necessary for (R,S)-ketamine's effects on behavioral despair in the forced swim test and on hyponeophagia in the novelty suppressed feeding paradigm, as well on fear behavior following contextual fear conditioning. In female mice, GluN2B expression is necessary for effects on hyponeophagia in novelty suppressed feeding. These effects were not replicated when ablating GluN2B from 2-week-old adult-born neurons. We also find that ablating neurogenesis increases fear expression in contextual fear conditioning, which is buffered by (R,S)-ketamine administration. In line with previous studies, these results suggest that 6-week-old adult-born hippocampal neurons expressing GluN2B partially modulate (R,S)-ketamine's rapid-acting effects. Future work targeting these 6-week-old adult-born neurons may prove beneficial for increasing the efficacy of (R,S)-ketamine.

Perception of emotional facial expressions in aggression and psychopathy.

Altered affective state recognition is assumed to be a root cause of aggressive behavior, a hallmark of psychopathologies such as psychopathy and antisocial personality disorder. However, the two most influential models make markedly different predictions regarding the underlying mechanism. According to the integrated emotion system theory (IES), aggression reflects impaired processing of social distress cues such as fearful faces. In contrast, the hostile attribution bias (HAB) model explains aggression with a bias to interpret ambiguous expressions as angry. In a set of four experiments, we measured processing of fearful and angry facial expressions (compared to neutral and other expressions) in a sample of 65 male imprisoned violent offenders rated using the Hare Psychopathy Checklist-Revised (PCL-R, Hare, R. D. (1991). The psychopathy checklist-revised. Toronto, ON: Multi-Health Systems) and in 60 age-matched control participants. There was no evidence for a fear deficit in violent offenders or for an association of psychopathy or aggression with impaired processing of fearful faces. Similarly, there was no evidence for a perceptual bias for angry faces linked to psychopathy or aggression. However, using highly ambiguous stimuli and requiring explicit labeling of emotions, violent offenders showed a categorization bias for anger and this anger bias correlated with self-reported trait aggression (but not with psychopathy). These results add to a growing literature casting doubt on the notion that fear processing is impaired in aggressive individuals and in psychopathy and provide support for the idea that aggression is related to a hostile attribution bias that emerges from later cognitive, post-perceptual processing stages.

Pupillary Responses to Dynamic Negative Versus Positive Facial Expressions of Emotion in Children and Parents: Links to Depression and Anxiety.

Witnessing emotional expressions in others triggers physiological arousal in humans. The current study focused on pupil responses to emotional expressions in a community sample as a physiologicalindex of arousal and attention. We explored the associations between parents' and offspring's responses to dynamic facial expressions of emotion, as well as the links between pupil responses and anxiety/depression. Children (N=90, MAge=10.13, range=7.21-12.94, 47 girls) participated in this lab study with one of their parents (47 mothers). Pupil responses were assessed in a computer task with dynamic happy, angry, fearful, and sad expressions, while participants verbally labeled the emotion displayed on the screen as quickly as possible. Parents and children reported anxiety and depression symptoms in questionnaires. Both parents and children showed stronger pupillary responses to negative versus positive expressions, and children's responses were overall stronger than those of parents. We also found links between the pupil responses of parents and children to negative, especially to angry faces. Child pupil responses were related to their own and their parents' anxiety levels and to their parents' (but not their own) depression. We conclude that child pupils are sensitive to individual differences in parents' pupils and emotional dispositions in community samples.

Acute sleep disruption reduces fear memories in male and female mice.

Sleep problems are a prominent feature of mental health conditions including post-traumatic stress disorder (PTSD). Despite its potential importance, the role of sleep in the development of and/or recovery from trauma-related illnesses is not understood. Interestingly, there are reports that sleep disruption immediately after a traumatic experience can reduce fear memories, an effect that could be utilized therapeutically in humans. While the mechanisms of this effect are not completely understood, one possible explanation for these findings is that immediate sleep disruption interferes with consolidation of fear memories, rendering them weaker and more sensitive to intervention. Here, we allowed fear-conditioned mice to sleep immediately after fear conditioning during a time frame (18 h) that includes and extends beyond periods typically associated with memory consolidation before subjecting them to 6-h of sleep disruption. Mice exposed to this delayed regimen showed dramatic reductions in fear during tests conducted immediately after sleep disruption, as well as 24 h later. This sleep disruption regimen also increased levels of mRNA encoding brain-derived neurotrophic factor (BDNF), a molecule implicated in neuroplasticity, in the basolateral amygdala (BLA), a brain area implicated in fear and its extinction. These findings raise the possibility that the effects of our delayed sleep disruption regimen are not due to disruption of memory consolidation, but instead are caused by BDNF-mediated neuroadaptations within the BLA that actively suppress expression of fear. Treatments that safely reduce expression of fear memories would have considerable therapeutic potential in the treatment of conditions triggered by trauma.

Cocaine diminishes consolidation of cued fear memory in female rats through interactions with ventral hippocampal D2 receptors

In addition to cocaine's addictive properties, cocaine use may lead to heightened risk-taking behavior. The disruptive effects of cocaine on aversive memory formation may underlie this behavior. The present study investigated the effects of cocaine on fear memory using a cued fear conditioning paradigm in female Sprague Dawley rats, and further determined the role of D2 receptors in modulating the effect of cocaine on cued fear expression. Animals received six evenly spaced shocks preceded by a tone. The following day, rats were returned to the fear chamber where tones, but no shocks, were delivered. In Experiment 1, separate or concurrent administrations of cocaine (15 mg/kg; i.p.) and the D2 receptor antagonist eticlopride (0.1 mg/kg; i.p.) were given immediately after conditioning trials. It was determined that cocaine administration during the consolidation period diminished the expression of cued fear during the subsequent test day. Concurrent eticlopride administration attenuated this effect, indicating the involvement of D2 receptors in the deleterious effects of cocaine on fear memory consolidation. In Experiment 2, eticlopride (0.05 μg) was infused directly into the ventral hippocampus (VH) after fear conditioning and before cocaine administration. Cocaine continued to disrupt consolidation of cued and contextual fear memory, and concurrent intra-VH eticlopride blocked this effect, thereby demonstrating that VH D2 receptors mediate cocaine-induced impairment of fear memory consolidation. Overall, the present study provides evidence that acute cocaine administration impairs aversive memory formation and establishes a potential circuit through which cocaine induces its detrimental effects on fear memory consolidation.

Predictability modulates the early neural coding of spatially unattended fearful faces

In this study, we assessed whether predictability affected the early processing of facial expressions. To achieve this, we measured lateralised early- and mid-latency event-related potentials associated with visual processing. Twenty-two participants were shown pairs of bilaterally presented fearful, happy, angry, or scrambled faces. Participants were required to identify angry faces on a spatially attended side whilst ignoring happy, fearful, and scrambled faces. Each block began with the word HAPPY or FEARFUL which informed participants the probability at which these faces would appear. Attention effects were found for the lateralised P1, suggesting that emotions do not modulate the P1 differentially, nor do predictions relating to emotions. Pairwise comparisons demonstrated that, when spatially unattended, unpredicted fearful faces produced larger lateralised N170 amplitudes compared to predicted fearful faces and unpredicted happy faces. Finally, attention towards faces increased lateralised EPN amplitudes, as did both fearful expressions and low predictability. Thus, we demonstrate that the N170 and EPN are sensitive to top-down predictions relating to facial expressions and that low predictability appears to specifically affect the early encoding of fearful faces when unattended, possibly to initiate attentional capture.