In Vivo Hippocampal Acetylcholine Release During Exposure to Acute Stress

Hippocampal extracellular acetylcholine (ACh) and choline levels were evaluated using in vivo microdialysis in male Fischer 344 rats before, during, and following an 80-min exposure to two different stress conditions. Measurements were taken in rats restrained and immersed in a water bath containing either 37 degreesC (normothermic-restraint) or 20 degreesC (cold-restraint) water. Results were compared to normothermic-freely-moving rats. Cold-restrained rats displayed decreased ACh levels during cold exposure relative to both normothermic-restrained and normothermic-freely-moving rats. By the end of the cold exposure period and following removal from cold, ACh levels had returned to near-baseline values. Normothermic-restrained rats had levels similar to those of normothermic-freely-moving rats, except for a marked increase in ACh following removal from restraint. Cold-restrained rats displayed a gradual elevation in choline levels during cold stress, followed by a gradual decline after stress termination, whereas both normothermic-restrained and normothermic-freely-moving rats displayed gradual decreases during the microdialysis session. These findings demonstrate that central cholinergic neurotransmission can be altered by the application of, and removal from, acute stressors. In addition, the results suggest a possible relationship between the magnitudes of both the stressor and its cholinergic consequences.     

Cyber-dehumanization: Violent video game play diminishes our humanity

Across two studies we show that engaging in violent video game play diminishes perceptions of our own human qualities. In addition, when other players are the targets of this violence it reduces our perceptions of their humanity also. In Study 1, we demonstrate that playing Mortal Kombat against another player reduces the perceived humanity of the self as well as the humanity of one's opponent (compared to playing a non-violent game). In Study 2 we replicate this effect on perceived humanity of the self when playing a violent game with a co-player. However, we find no dehumanization of co-players who are not the targets of violence. We demonstrate these effects cannot be reduced to mood, self-esteem, gender, or other characteristics of the game such as excitement and enjoyment. The findings provide a broader perspective from which to view previous work on the adverse effects of violent video games.     

Mindfulness Based Interventions for Youth

Application of mindfulness based interventions for youth is growing exponentially within clinical and educational settings. Proponents emphasize benefits in reduction of a wide range of psychopathology including internalizing and externalizing disorders, as well as enhancement of functioning and skills in attentional focus and concentration, emotion regulation, social and academic performance, adaptive coping, frustration tolerance, self-control, and self-esteem. Findings to date are encouraging, though research design reflects the nascent nature of the field and continues to be insufficient to confirm treatment efficacy or mechanisms of change. This article is aimed at providing the clinical practitioner with a review of the current state of the field with regard to application of mindfulness for youth, placing it in context of the broader history of the CBT movement. Specifically mindfulness based stress reduction, mindfulness based cognitive behavioral therapy, acceptance and commitment therapy, and dialectical behavior therapy treatments for youth are critically reviewed, and mindfulness as a technique and as a unifying mechanism of action in “third-wave” youth psychotherapies discussed. Developmental considerations are highlighted, and the application of mindfulness as a universal preventative health measure versus tertiary treatment intervention examined, with consideration for future directions.     

Understanding allies’ participation in social change: A multiple perspectives approach

The introduction to the EJSP special issue brings together recent literature on allyship. We present and discuss different definitions of allyship and highlight a multiple perspectives approach to understanding the predictors and consequences of allyship. This approach suggests that engagement in allyship can be driven by egalitarian and non-egalitarian motivations and that the behaviours identified as allyship can have different meanings, causes and consequences depending on whether researchers take into account the allies’ perspective or the disadvantaged groups’ perspective. We use this approach as an organizing principle to identify themes that emerge in the papers included in this special issue. We start with four papers that consider the perspective of the advantaged group, followed by two papers that consider the perspective of the disadvantaged group. Finally, we introduce two theoretical papers that examine the relations between disadvantaged groups and allies, and we set out directions for future research.     

Don't mind meat? The denial of mind to animals used for human consumption

Many people like eating meat, but most are reluctant to harm things that have minds. The current three studies show that this dissonance motivates people to deny minds to animals. Study 1 demonstrates that animals considered appropriate for human consumption are ascribed diminished mental capacities. Study 2 shows that meat eaters are motivated to deny minds to food animals when they are reminded of the link between meat and animal suffering. Finally, Study 3 provides direct support for our dissonance hypothesis, showing that expectations regarding the immediate consumption of meat increase mind denial. Moreover, this mind denial in turn reduces negative affect associated with dissonance. The findings highlight the role of dissonance reduction in facilitating the practice of meat eating and protecting cultural commitments.     

Changing Versus Protecting the Status Quo: Why Men and Women Engage in Different Types of Action on Behalf of Women

We investigate women’s and men’s willingness to engage in action on behalf of women, and we identify two distinct categories of behavior: action that aims to challenge gender inequality (feminist action) and action that aims to protect women from violence (protective action). Three online studies were conducted. For each study, a U.S. community sample was recruited. In Study 1 (n?=?602), women reported greater intentions to engage in feminist action than men did. Men, however, were just as willing as women to participate in protective action. In Study 2 (n?=?726), we replicated these gender differences and found that protective action was positively predicted by benevolent sexism among men. In Study 3 (N?=?582), we investigated why women reported greater intentions to engage in feminist action compared to men. We found that women were more aware of gender inequality, which was associated with identification as a feminist, and through this, intentions to engage in feminist action. Awareness of gender inequality also predicted intentions to engage in protective action among women. Men, however, were less aware of gender inequality, which was associated with the belief that feminist action leads to women having more rights than men do and subsequently greater willingness to participate in protective action. Our results can assist social policymakers and activists to develop appropriate campaigns for gender equality if their goal is to challenge, rather than protect women from, the status quo.     

Towards an understanding of performative allyship: Definition,antecedents and consequences

Adding rainbow filters in support of LGBTQ+ movements or changing profile pictures to black squares to show support for the BlackLivesMatter movement have become common contemporary expressions of solidarity. However, these actions are often criticized as being ‘performative’ and falling short of genuine social change. Despite its popularity, little is known about what performative allyship is and what its pitfalls or potential benefits may be. We review the existing psychological literature on intergroup relations and allyship to provide a definition and framework for studying performative allyship and its consequences for social change. We propose that the term performative allyship refers to easy and costless actions that often do not challenge the status quo and are motivated primarily by the desire to accrue personal benefits. The literature suggests that engaging in performative allyship may have a negative impact on the physical and mental well-being of disadvantaged groups, but also on allies. We discuss negative and some positive consequences of engagement in performative allyship on disadvantaged groups, allies and society at large and provide directions for future research.     

Selective enhancement of fear learning and resistance to extinction in a mouse model of acute early life trauma

Early life stress (ELS) experiences can cause changes in cognitive and affective functioning. This study examined the persistent effects of a single traumatic event in infancy on several adult behavioral outcomes in male and female C57BL/6J mice. Mice received 15 footshocks in infancy and were tested for stress-enhanced fear learning, extinction learning, discrimination and reversal learning, and novel object recognition. Infant trauma potentiated fear learning in adulthood and produced resistance to extinction but did not influence other behaviors, suggesting restricted effects of infant trauma on behaviors reliant on cortico-amygdala circuitry.

Exposure to traumatic events early in childhood is associated with the development of psychiatric disorders (Copeland et al. 2018) and deficits in cognitive and affective functioning (Pechtel and Pizzagalli 2011) in adulthood. In humans, early life stress (ELS) is defined as experiencing traumatic events in childhood (Pechtel and Pizzagalli 2011). Rodent models of ELS suggest that acute versus chronic stress may differentially alter systems that regulate the stress response, producing different behavioral outcomes in adulthood (Pryce et al. 2002; Musazzi et al. 2017).Stress-enhanced fear learning (SEFL), a powerful preclinical model of PTSD- and addiction-like behaviors, captures the enduring, maladaptive effects of a single traumatic event on behavior (Rau et al. 2009; Meyer et al. 2013; Radke et al. 2019). In these studies, exposure to 15 footshocks enhances contextual fear conditioning later in life. For infant SEFL, enhanced contextual fear conditioning occurs months after the initial stressful experience and in the absence of memory for the context in which ELS was experienced (Poulos et al. 2014; Quinn et al. 2014). SEFL protocols have been used to model adult or infant trauma in rats (e.g., Rau et al. 2009; Poulos et al. 2014; Quinn et al. 2014) and have been extended to adult mice (Sillivan et al. 2017; Hassien et al. 2020; Pennington et al. 2020). However, to our knowledge, no studies have established the use of acute, infant footshock as a model of ELS in mice.We sought to characterize the effects of acute, infant trauma exposure across several types of learning in adult mice. We tested mice exposed to 15 footshocks on postnatal day (PND) 17 for contextual fear learning, extinction of fear, discrimination and reversal learning, and novel object recognition. Our results suggest that exposure to acute infant trauma enhances fear learning and resistance to extinction in adulthood, but does not alter other types of learning.Male and female C57BL/6J mice were generated from breeding pairs from The Jackson Laboratory. Mice were group-housed (two to four mice/cage) post-weaning and were provided food and water ad libitum, unless otherwise specified. Mice were on a 12:12 light/ dark cycle. Other than trauma exposure, all behavioral tests were conducted during adulthood (PND 60+). Animals were cared for in accordance with the guidelines set by the National Institutes of Health and all procedures were approved by the Institutional Animal Care and Use Committee at Miami University.We first established that exposure to infant footshock produces enhanced contextual fear conditioning in adulthood. Mice were placed in a MED-Associates conditioning chamber (context A) on PND 17 (Fig. 1A; after Quinn et al. 2014). Context A was brightly lit, contained a uniform grid floor, was scented with vanilla (50%), and was cleaned with odorless 5% sodium hydroxide. Mice received either 0 or 15 footshocks (1 mA, 1 sec) during a 60-min session beginning 180 sec following placement in the chamber. Progressive scan video cameras containing visible light filters monitored mice throughout the session. Video Freeze software (Med Associates, Inc.) analyzed the video and data were expressed as percent of time spent freezing during the session. Fear conditioning experiments were powered to detect sex differences with an n of eight per sex. Because differences were not observed when sex was included as a factor in analyses, all reported results represent data from both sexes. Due to computer malfunction, fear conditioning sessions from 14 mice were hand scored according to standard time-sampling procedures (Chowdhury et al. 2005) and data from three mice had to be excluded on extinction session 2.Open in a separate windowFigure 1.Acute infant trauma produces stress-enhanced fear learning in adulthood. (A) Experimental timeline and visual representation of context A and context B. Infant trauma consisted of 15 footshocks or no footshocks on PND 17 in context A. Adult fear conditioning consisted of one footshock (black bars) or no footshock (blue bars) on PND 60 in context B. Extinction was assessed in context B. Memory of the infant trauma was assessed in context A. Stress enhanced fear learning (SEFL) was observed in mice who were exposed to early life stress (15 shocks) and fear conditioning (one shock) for extinction test 1 (B) and extinction test 2 (C). (*) P < 0.05, (**) P < 0.01 versus no/one shock group (Holm–Sidak test). (D) Mice showed little freezing, indicating an absence of fear memory for the infant trauma in context A. Data are means ± SEM.Contextual fear conditioning occurred on PND 60 in a novel context (context B). Context B was dark with a staggered grid floor and cleaned and scented with acetic acid (5%). Baseline freezing during the first 180 sec in this novel context was assessed and used to measure generalization between the stress exposure context (context A) and the novel fear conditioning context (context B). Mice received either 0 or 1 footshocks (1 mA, 1 sec) 180 sec into a 3.5-min session. Thus, there were four groups (infant trauma/adult fear conditioning): no/no shock, n = 14; 15/no shock, n = 15; no/one shock, n = 15; and 15/one shock, n = 18. To test extinction of fear memory, mice were reintroduced to context B for two 8-min sessions, separated by 24 h. Finally, mice were reintroduced to context A for an 8-min retention test of the original context.Mice exposed to 15 footshocks in infancy and conditioned with one footshock as adults exhibited robust SEFL. There were no differences in baseline freezing during the adult fear conditioning session (infant trauma: F_(1,47) = 2.67, P = 0.109, no/no shocks = 0.26 ± 0.15; no/one shock = 2.17 ± 0.64; 15/no shocks = 2.14 ± 0.76; 15/one shock = 7.17 ± 3.25; all data mean ± SEM). For extinction sessions (Fig. 1B,C), a mixed-effects analysis identified main effects of trauma (F_(1,58) = 5.68, P = 0.020), fear conditioning (F_(1,58) = 12.40, P < 0.001), and session (F_(1,55) = 5.25, P = 0.026). There was a significant interaction between fear conditioning and session (F_(1,55) = 7.10, P = 0.010). Two-way ANOVA was next used to examine each test session. For session 1 (Fig. 1B), there were main effects of trauma (F_(1,58) = 5.72, P = 0.020) and fear conditioning (F_(1,58) = 21.10, P < 0.001). The interaction of trauma and fear conditioning did not reach the threshold for significance (F_(1,58) = 2.87, P = 0.096). Follow-up Holm Sidak''s tests revealed that adult fear conditioning produced greater freezing in mice exposed to infant footshock vs. trauma-naïve mice (P = 0.008). For the second extinction test (Fig. 1C), the main effects of trauma (F_(1,55) = 3.72, P = 0.059) and fear conditioning (F_(1,55) = 3.92, P = 0.053) approached the threshold for significance. Follow-up Holm Sidak''s tests revealed that trauma-exposed mice froze more than trauma-naïve mice following adult fear conditioning only (P = 0.042). When tested for memory of the context used for trauma-exposure on PND 17 (context A), mice demonstrated minimal freezing and two-way ANOVA found no significant main effects or interactions (Fs < 1.39) (Fig. 1D). Percent freezing in infancy and in extinction test 1 in adulthood were correlated (r = −0.481, P = 0.043) for the 15/one group alone. Activity bursts in infancy did not correlate with freezing behavior in adulthood. These results indicate that mice exposed to infant trauma who experienced fear conditioning in adulthood exhibited SEFL on the first and second extinction sessions but the memory of the trauma experience was not retained into adulthood.Since PTSD is associated with deficits in fear extinction (Zuj et al. 2016), we next examined extinction learning using 30-min sessions (Fig. 2A). Mice were exposed to acute infant trauma (0 or 15 footshocks) on PND 17. On PND 60, mice were reintroduced to context A for an 8-min test of memory for the original ELS context prior to fear conditioning (no/one shock = 2.41 ± 0.58; 15/one shock = 3.50 ± 0.42; no/three shocks = 1.86 ± 0.43). On PND 61 fear conditioning occurred in context B. Since we observed that trauma-naïve mice displayed very little fear conditioning following one footshock (Fig. 1B,C), mice in this experiment received either one or three footshocks during adult fear conditioning. There were three groups (infant trauma/adult fear conditioning): no/one shock, n = 17; 15/one shock, n = 17; no/three shocks, n = 18. Retention of fear memory was tested for five subsequent days (PND 62–66) in context B during 30-min sessions.Open in a separate windowFigure 2.Extinction of fear learning is impaired following acute infant trauma. (A) Experimental timeline. Infant trauma consisted of 15 footshocks or no footshocks on PND 17 in context A. Adult fear conditioning consisted of one (yellow symbols) or three (blue symbols) footshocks in trauma-naïve mice and one footshock (black symbols) in trauma-exposed mice in context B. Memory of the infant trauma was assessed in context A. Mice received five extinction sessions in context B. (B) On extinction day 1, trauma-exposed mice initially froze at the same level as trauma-naïve mice conditioned with three footshocks but fear persisted longer, demonstrating within-session resistance to extinction. (*) P < 0.05, (**) P < 0.01 15/one shock group versus no/one shock group; (^#) P < 0.05 15/one shock group versus no/three shocks group; (^†) P < 0.05, (^‡) P < 0.01 no/one shock group versus no/three shock group (Holm–Sidak test). (C) Freezing was averaged across the first 8 min of each extinction session. Trauma-exposed mice demonstrated resistance to extinction across sessions. On session 1, both trauma-exposed (15/one shock group) and mice conditioned with three footshocks (no/three shock group) had elevated freezing compared to mice conditioned with one footshock. On session 2, freezing in trauma-exposed mice remained elevated and was greater than in the other two groups. (**) P < 0.01 15/one shock group versus no/one shock group. (^##) P < 0.01 15/one shock group versus no/three shocks group. (^†) P < 0.05 no/one shock group versus no/three shocks group (Holm–Sidak test). Data are means ± SEM.On the first extinction session, there were significant main effects of time (F_(29,1421) = 2.23, P < 0.001) and group (F_(2,49) = 3.54, P = 0.037) and a significant interaction (F_(58,1421) = 1.93, P < 0.001). Holm–Sidak follow-up comparisons revealed that trauma-exposed mice (15/one shock) and mice conditioned with three footshocks during adulthood (no/three shocks) froze more than the no/one shock group during the first 3 min (P < 0.05 for minute 1 and P < 0.01 for minutes 2 and 3) of the first extinction session (Fig. 2B). Trauma-exposed mice continued to freeze more than the no/one shock group during minutes 4–7 (P < 0.01) and minute 11 (P < 0.05). Freezing in the no/3 shocks group was similar to trauma-exposed mice for the first 4 min but diminished sooner, evidenced by a significant difference between these groups during minutes 5, 6, and 9 (P < 0.05). These results suggest that conditioning with three footshocks produces similar levels of fear in trauma-naïve mice as conditioning with one footshock in trauma-exposed mice, but that within-session extinction is delayed in the trauma-exposed group.To examine extinction across the five sessions, we averaged freezing during the first 8 min of each session. We found significant main effects of session (F_(4,196) = 22.92, P < 0.001) and group (F_(2,49) = 6.38, P = 0.003) and a significant interaction (F_(8,196) = 2.75, P = 0.007). Holm–Sidak follow-up comparisons revealed that mice exposed to infant trauma (15/one shock) and mice in the no/three shock group froze more than those in the no/one shock group on extinction session 1 (P < 0.01 and P < 0.05, respectively) (Fig. 2C). On session 2, freezing was greater in trauma-exposed mice versus both other groups (P < 0.01). Percent freezing in infancy did not correlate with freezing behavior in adulthood. Activity bursts in infancy correlated with freezing behavior in adulthood on extinction test 1 (r = −0.558, P = 0.020). These results further suggest that infant trauma produces resistance to extinction.To determine whether the behavioral alterations observed in mice exposed to infant trauma extend to other types of learning, we tested the effects of infant footshock on operant discrimination and reversal learning for food reward and novel object recognition. For discrimination and reversal learning, we used a subset of mice from the first experiment (no shock = 20, 15 shocks = 17) restricted to 85% of free-feeding weight. Mice underwent one habituation day with ten 14-mg grain pellets (Bio Serv) in their home cages. The following day, mice began 15-min training sessions in a standard mouse operant chamber (Med Associates). There were two nose-poke holes and a reward receptacle on one wall of the chamber and a house light and speaker on the opposite wall. The chamber was housed in a sound and light-attenuating box and connected to a computer for data collection (Med-PC V software suite). For all sessions, the house light was off and lights in the nose-poke holes were on. Following a correct response, a 2-sec, 65-dB tone sounded and there was a timeout period of 20 sec following reward delivery during which the lights above the nose-poke holes were off and no rewards could be earned.During the first session, 30 pellets were automatically delivered into the reward receptacle. Next, mice were trained to respond for the food reward on a fixed ratio 1 (FR1) schedule by responding at either nose-poke hole until meeting criterion of 30 responses in 15-min. For discrimination, mice were trained to respond at the active nose-poke hole (100% probability of reward), which was randomly assigned to the left or right side. The contingencies of the active and inactive nose-pokes holes were reversed once criterion was met (≥30 rewards with 85% reinforced responses over two consecutive sessions).Neither sex nor adult fear conditioning affected any measure of discrimination and reversal learning, so all results are reported collapsed across these two factors. Two trauma-exposed females did not acquire the discrimination in 25 sessions and were not advanced to reversal. Data were analyzed using mixed-effects analyses with phase (i.e., acquisition and reversal) as the within-subjects factor. There were no differences between groups in the total number of sessions required to complete discrimination (no shock = 5.70 ± 0.69; 15 shock = 6.82 ± 1.50) or reversal (no shock = 9.40 ± 0.98; 15 shock = 7.73 ± 1.21). Mice made more total reinforced (main effect of phase: F_(1,33) = 11.62, P = 0.002) and total nonreinforced (main effect of phase: F_(1,33) = 42.54, P < 0.001) responses during reversal but there were no effects of infant trauma on behavior (Fig. 3A,B). These results indicate that acute infant trauma does not influence acquisition of operant discrimination learning or behavioral flexibility in adulthood.Open in a separate windowFigure 3.Acute infant trauma does not affect discrimination and reversal learning or novel object recognition. (A,B) Following infant trauma on PND 17 (no footshock, blue, or 15 footshocks, black), adult mice were trained to respond for a food pellet in an operant, spatial discrimination and reversal learning task. Following acquisition of the discrimination (left or right nose-poke hole reinforced 100% of the time) the contingencies of the responses were reversed. Mice made more total reinforced (A) and unreinforced (B) responses during reversal versus acquisition across sessions ([**] P < 0.01, main effect of training phase) but there were no effects of infant trauma exposure. (C) A separate cohort of mice exposed to infant trauma (no or 15 footshocks on PND 17) was tested for novel object recognition by assessing exploration of a novel object 1 and 24 h after exposure to the familiar object. Mice explored the novel object more ([**] P < 0.01, main effect of object, main effect of testing session, and interaction of object × testing session) but there were no effects of infant trauma exposure. Data are means ± SEM.In a new cohort of mice (no shock = 16, 15 shocks = 16), novel object recognition following infant footshock was tested. In adulthood, mice were handled for 1–3 min for two consecutive days. The following day, mice were placed in 20 × 18 × 25-cm apparatus with white floors and patterned walls (Panlab) for a 10-min habituation session to the chamber. Twenty-four hours later, mice were returned to the apparatus now containing two sample objects for 10-min initial exposure to the objects (two identical small plastic caps, 0.8 cm tall with a 2.1-cm diameter) placed in the back right and left corners of the apparatus. One hour later, mice were returned to the apparatus for a 3-min session (1-h test) where one of the sample objects was replaced with a novel object (a 2.5 × 1.2 × 1.5-cm Lego tower). The object replaced was alternated for each mouse. Mice were returned to the same box 24 h later for another 3-min session (24-h test) with the opposite cap replaced with a second novel object (a 3 × 1.5-cm black binder clip). ANY-maze software recorded each session. Time spent interacting with each object was measured by two independent raters and averaged (after Bevins and Besheer 2006).A three-way ANOVA revealed a significant main effect of object (familiar vs. novel; F_(1,60) = 59.84, P < 0.001). There was also a main effect of testing session (1-h vs. 24-h test; F_(1,60) = 7.89, P = 0.007) and an interaction of object × testing session (F_(1,60) = 11.48, P = 0.001) (Fig. 3C,D). Interrater reliability was confirmed using Pearson''s correlation (r = 0.942). These results indicate that acute infant trauma does not influence hippocampal-dependent object recognition memory.Our results demonstrate that an acute traumatic experience during infancy affects some learned behaviors during adulthood. As previously reported in rats (Quinn et al. 2014; Poulos et al. 2014), 15 footshocks on PND 17 increased adult contextual fear conditioning in mice. We also demonstrated for the first time that the infant SEFL protocol produces resistance to extinction (within-session and between-session) and that behavior in a discrimination and reversal learning task and a novel object recognition task are unaffected. These findings establish the use of infant footshock to study SEFL in mice and further support the use of this paradigm as a model of PTSD-like behavior.The effects observed here differ from those commonly observed following chronic ELS manipulations such as limited nesting and bedding (Ivy et al. 2008; Molet et al. 2016) or maternal separation (Nishi et al. 2014). Chronic ELS impairs acquisition of fear conditioning in adult rodents (Kosten et al. 2006; Stevenson et al. 2009; Lesuis et al. 2019) and performance on hippocampal-dependent memory tasks (Rice et al. 2008; Naninck et al. 2015), for example. These behavioral differences suggest that acute and chronic infant stressors alter neural circuits in unique ways that are worthy of further study.Since the tasks used here rely on distinct neural circuits, the current results provide novel insight into how acute infant trauma impacts brain function. The effects of acute ELS were restricted to fear acquisition and extinction, suggesting alterations in cortico-amygdala circuits (Tovote et al. 2015). However, preservation of novel object recognition as well as discrimination and reversal learning suggest that hippocampal and striatal circuits likely remain intact (Cohen and Stackman 2015; Izquierdo et al. 2017). These findings can guide future studies concerning the neural mechanisms of acute ELS effects on behavior.