Testosterone administration decreases sensitivity to angry facial expressions in healthy males: A computational modeling approach

Previous research indicates that higher testosterone levels are related to increased aggressive and dominant behaviors, particularly in males. One possible mechanism for these hormone-behavior associations could involve threat perception. However, the causal influence of testosterone on men's recognition of threatening facial expressions remains unknown. Here, we tested the causal effect of exogenous testosterone on men's sensitivity to facial threat by combining a psychophysical task with computational modeling. We administered a single dose (150 mg) of testosterone or placebo gel to healthy young men (n = 120) in a double-blind, placebo-controlled, between-participant design. Participants were presented with morphed emotional faces mixing anger/fear and neutral expressions and made judgments about the emotional expression. Across typical regression analysis, signal detection analysis, and drift diffusion modeling, our results consistently showed that individuals who received testosterone (versus placebo) exhibited a lower perceived sensitivity to angry facial expressions. But we observed no significant effects of testosterone administration on fearful facial expressions. The findings indicate that testosterone attenuates sensitivity to facial threat, especially angry facial expressions, which could lead to a misestimation of others' dominance and an increase in one's own aggressive and dominant behaviors.

The neurobiology of social stress resulting from Racism: Implications for pain disparities among racialized minorities

Extant literature posits that humans experience two types of threat: physical threat and social threat. While describing pain as "physical" or "social" can be helpful for understanding pain origins (i.e., broken bone versus lost relationship), this dichotomy is largely artificial and not particularly helpful for understanding how the human brain experiences pain. One real world example of social exclusion and rejection that is threatening and likely to bring about significant stress is racism. Racism is a system of beliefs, practices, and policies that operates to disadvantage racialized minorities while providing advantage to those with historical power, particularly White people in the United States and most other Western nations. The objective of this Mini-Review is to present evidence in support of the argument that racism promotes physical pain in racialized minorities, which in turn promotes chronic pain disparities. First, we provide a theoretical framework describing how racism is a potent stressor that affects the health and well-being of racialized minorities. We will then address the neurobiological underpinnings linking racism to social threat, as well as that linking social threats and physical pain. Finally, we will discuss how the perception of social threat brought about by racism may undermine pain management efforts.

Unconscious social relation threats: Invisible boss face biases attention

Threatening stimuli as a kind of salient information often guide attentional orienting. Besides physically threatening stimuli, social threats can also strongly bias attention, even in the absence of conscious awareness. However, the available evidence mainly came from studies on an emotional face. It is unclear whether social relation threats, such as a boss face without emotional expressions, can also direct attentional orienting unconsciously. This study aimed to reveal the extent to which the attentional system has developed to process threatening stimuli by exploring whether invisible social relation threats unconsciously biased attention. We asked graduate and undergraduate students to perform a modified Posner's cue-target task, in which the probe was preceded by a pair of competitive face cues (an advisor's face and another faculty member's face), rendered invisible through continuous flash suppression. Experiment 1a's results showed that the advisor's face reflexively oriented graduate students' spatial attention, which was significantly correlated with subjective social threat evaluation. However, Experiment 1b showed that an invisible advisor's face did not induce the same effect in undergraduate students, as they reported significantly fewer threats from their advisors than graduates. To ensure the robustness of this new effect, we preregistered a replicate study and successfully replicated the above results in Experiments 2a and 2b. Our findings provide evidence for the existence of an attentional orienting bias toward invisible social relation threats. These results suggest that the attentional system evolved to promote the exploration of our visual environment for threatening social relation signals.

Freeze-like responses to pain in humans and its modulation by social context

Background

Maladaptive defensive responses such as excessive avoidance behavior have received increasing attention as a main mechanism for the development and maintenance of chronic pain complaints. However, another defensive response which is commonly studied in animals as a proxy for fear is freezing behavior. No research to date has investigated human freezing behavior in the context of pain. In addition, there is an increasing realization that social context can affect pain-relevant processes such as pain experience and pain behavior but less is known about the effects of social context on defensive responses to pain. Hence, this study investigated freezing behavior and facial pain expression in the context of pain, and their modulation by social context.

Methods

Healthy, pain-free participants (N = 39) stood on a stabilometric force platform in a threatening or safe social context, which was manipulated using angry or happy facial stimuli. In some trials, an auditory cue (conditioned stimulus; CS) predicted the occurrence of painful electrocutaneous stimulus (unconditioned stimulus; pain-US). We assessed body sway (an index of freezing), heart rate, facial pain expression, self-reported pain intensity, unpleasantness, and pain-US expectancy during the CS and the context alone (no CS).

Results

The results were mixed. Neither the anticipation of pain, nor social context affected body sway. Heart rate and painful facial expression were reduced in the threatening social context at high anxiety levels. A threatening social context also elicited higher pain-US expectancy ratings. In sum, a threatening social context increases the expectation of pain, but reduces the facial expression of pain and lowers heart rate in highly anxious individuals.

Longitudinal associations between amygdala reactivity and cannabis use in a large sample of adolescents

RATIONALE

The amygdala is a key brain structure to study in relation to cannabis use as reflected by its high-density of cannabinoid receptors and functional reactivity to processes relevant to drug use. Previously, we identified a correlation between cannabis use in early adolescence and amygdala hyper-reactivity to angry faces (Spechler et al. 2015).

OBJECTIVES

Here, we leveraged the longitudinal aspect of the same dataset (the IMAGEN study) to determine (1) if amygdala hyper-reactivity predicts future cannabis use and (2) if amygdala reactivity is affected by prolonged cannabis exposure during adolescence.

METHODS

First, linear regressions predicted the level of cannabis use by age 19 using amygdala reactivity to angry faces measured at age 14 prior to cannabis exposure in a sample of 1119 participants. Next, we evaluated the time course of amygdala functional development from age 14 to 19 for angry face processing and how it might be associated with protracted cannabis use throughout this developmental window. We compared the sample from Spechler et al. 2015, the majority of whom escalated their use over the 5-year interval, to a matched sample of non-users.

RESULTS

Right amygdala reactivity to angry faces significantly predicted cannabis use 5 years later in a dose-response fashion. Cannabis-naïve adolescents demonstrated the lowest levels of amygdala reactivity. No such predictive relationship was identified for alcohol or cigarette use. Next, follow-up analyses indicated a significant group-by-time interaction for the right amygdala.

CONCLUSIONS

(1) Right amygdala hyper-reactivity is predictive of future cannabis use, and (2) protracted cannabis exposure during adolescence may alter the rate of neurotypical functional development.

Social trauma and its association with posttraumatic stress disorder and social anxiety disorder

The key characteristic of a traumatic event as defined by the Diagnostic and Mental Manual of Mental Disorders (DSM) seems to be a threat to life. However, evidence suggests that other types of threats may play a role in the development of PTSD and other disorders such as social anxiety disorder (SAD). One such threat is social trauma, which involves humiliation and rejection in social situations. In this study, we explored whether there were differences in the frequency, type and severity of social trauma endured by individuals with a primary diagnosis of SAD (n = 60) compared to a clinical control group of individuals with a primary diagnosis of obsessive compulsive disorder (OCD, n = 19) and a control group of individuals with no psychiatric disorders (n = 60). The results showed that most participants in this study had experienced social trauma. There were no clear differences in the types of experiences between the groups. However, one third of participants in the SAD group (but none in the other groups) met criteria for PTSD or suffered from clinically significant PTSD symptoms in response to their most significant social trauma. This group of SAD patients described more severe social trauma than other participants. This line of research could have implications for theoretical models of both PTSD and SAD, and for the treatment of individuals with SAD suffering from PTSD after social trauma.

Neurophysiological evidence for distinct biases in emotional face processing associated with internalizing and externalizing symptoms in children

Attentional bias to threat has been implicated in both internalizing and externalizing disorders. This study utilizes event-related potentials to examine early stages of perceptual attention to threatening (angry or fearful) versus neutral faces among a sample of 200 children ages 6-8 years from a low-income, urban community. Although both internalizing and externalizing symptoms were associated with processing biases, the nature of the bias differed between these two symptom domains. Internalizing symptoms were associated with heightened early attentional selection (P1) and later perceptual processing (P2) of fearful faces. In contrast, externalizing symptoms were associated with reduced early attentional selection (P1) of fearful faces and enhanced perceptual processing (P2) of neutral faces, possibly indicative of a hostile interpretation bias for ambiguous social cues. These results provide insight into the distinct cognitive-affective processes that may contribute to the etiology and maintenance of internalizing and externalizing psychopathology.

Understanding Brain Mechanisms of Reactive Aggression

PURPOSE OF REVIEW

To review the current literature on biobehavioral mechanisms involved in reactive aggression in a transdiagnostic approach.

RECENT FINDINGS

Aggressive reactions are closely related to activations in the brain's threat circuitry. They occur in response to social threat that is experienced as inescapable, which, in turn, facilitates angry approach rather than fearful avoidance. Provocation-induced aggression is strongly associated with anger and deficits in cognitive control including emotion regulation and inhibitory control. Furthermore, the brain's reward system plays a particular role in anger-related, tit-for-tat-like retaliatory aggression in response to frustration. More research is needed to further disentangle specific brain responses to social threat, provocation, and frustration. A better understanding of the psychological and neurobiological mechanisms involved in reactive aggression may pave the way for specific mechanism-based treatments, involving biological or psychotherapeutic approaches or a combination of the two.

Stress, sex hormones, inflammation, and major depressive disorder: Extending Social Signal Transduction Theory of Depression to account for sex differences in mood disorders

Social Signal Transduction Theory of Depression is a biologically plausible, multi-level theory that describes neural, physiologic, molecular, and genomic mechanisms that link experiences of social-environmental adversity with internal biological processes that drive depression pathogenesis, maintenance, and recurrence. Central to this theory is the hypothesis that interpersonal stressors involving social threat (e.g., social conflict, evaluation, rejection, isolation, and exclusion) upregulate inflammatory processes that can induce several depressive symptoms, including sad mood, anhedonia, fatigue, psychomotor retardation, and social-behavioral withdrawal. The original article describing this formulation (Psychol Bull 140:774-815, 2014) addressed critical questions involving depression onset and recurrence, as well as why depression is strongly predicted by early life stress and comorbid with anxiety disorders and certain physical disease conditions, such as asthma, rheumatoid arthritis, chronic pain, and cardiovascular disease. Here, we extend the theory to help explain sex differences in depression prevalence, which is a defining feature of this disorder. Central to this extension is research demonstrating that ovarian hormone fluctuations modulate women's susceptibility to stress, brain structure and function, and inflammatory activity and reactivity. These effects are evident at multiple levels and are highly context-dependent, varying as a function of several factors including sex, age, reproductive state, endogenous versus exogenous hormones, and hormone administration mode and dose. Together, these effects help explain why women are at greater risk for developing inflammation-related depressed mood and other neuropsychiatric, neurodevelopmental, and neurodegenerative disorders during the reproductive years, especially for those already at heightened risk for depression or in the midst of a hormonal transition period.

Hide Your Pain: Social Threat Increases Pain Reports and Aggression, but Reduces Facial Pain Expression and Empathy

Earlier research studying the effects of social threat on the experience and expression of pain led to mixed results. In this study, female participants (N = 32) came to the lab with 2 confederates. Both confederates administered a total of 10 painful electrocutaneous stimuli to the participant. The framing of the administration was manipulated in a within-subjects design: In the low social threat condition the participant was told that the confederate could choose between 10 and 20 pain stimuli, thus they believed that this confederate chose to administer the minimum allowed number of pain stimuli. In the high social threat condition the confederate had a choice between 1 and 10 stimuli, thus they believed that this confederate chose to administer the maximum allowed number of stimuli. Participants reported on the intensity, unpleasantness, and threat value of the painful stimuli, and their facial expression was recorded. Moreover, aggression and empathy toward the confederates were assessed. As hypothesized, participants reported increased pain intensity, unpleasantness, and threat in the high social threat condition compared to the low social threat condition, but showed less facial pain expression. Finally, participants exhibited increased aggression and reduced empathy toward the confederate in the high social threat condition. PERSPECTIVE: Social threat reduces painful facial expression, but simultaneously increases pain reports, leading to a double burden of the person in pain. Additionally, social threat affected social relationships by increasing aggression and reducing empathy for the other.

Psychophysiological and Behavioral Responses to a Novel Intruder Threat Task for Children on the Autism Spectrum

We measured skin conductance response (SCR) to escalating levels of a direct social threat from a novel, ecologically-relevant experimental paradigm, the Intruder Threat Task. We simultaneously evaluated the contribution of social symptom severity and behavioral movement. Children with AS group showed less psychophysiological reactivity to social threat than controls across all three phases of the experiment. In the AS group, greater social impairment was significantly associated with reduced SCR. However, movement activity predicted SCR while diagnosis did not. Research and treatment need to account for the complex interplay of emotional reactivity and social behavior in AS. Psychophysiology studies of AS should consider the impact of possible confounds such as movement.

A systematic review of attentional biases in disorders involving binge eating

OBJECTIVE

Attentional bias (AB) may be one mechanism contributing to the development and/or maintenance of disordered eating. AB has traditionally been measured using reaction time in response to a stimulus. Novel methods for AB measurement include eye tracking to measure visual fixation on a stimulus, and electroencephalography to measure brain activation in response to a stimulus. This systematic review summarizes, critiques, and integrates data on AB gathered using the above-mentioned methods in those with binge eating behaviors, including binge eating, loss of control eating, and bulimia nervosa.

METHOD

Literature searches on PubMed and PsycInfo were conducted using combinations of terms related to binge eating and biobehavioral AB paradigms. Studies using AB paradigms with three categories of stimuli were included: food, weight/shape, and threat. For studies reporting means and standard deviations of group bias scores, Hedges' g effect sizes for group differences in AB were calculated.

RESULTS

Fifty articles met inclusion criteria and were reviewed. Individuals who binge eat in the absence of compensatory behaviors show an increased AB to food cues, but few studies have examined such individuals' AB toward weight/shape and threatening stimuli. Individuals with bulimia nervosa consistently show an increased AB to shape/weight cues and socially threatening stimuli, but findings for AB to food cues are mixed.

DISCUSSION

While there are important research gaps, preliminary evidence suggests that the combination of AB to disorder-specific cues (i.e., food and weight/shape) and AB toward threat may be a potent contributor to binge eating. This conclusion underscores previous findings on the interaction between negative affect and AB to disorder-specific cues. Recommendations for future research are provided.

Exogenous testosterone decreases men's personal distance in a social threat context

BACKGROUND

Testosterone can motivate human approach and avoidance behavior. Specifically, the conscious recognition of and implicit reaction to angry facial expressions is influenced by testosterone. The study tested whether exogenous testosterone modulates the personal distance (PD) humans prefer in a social threat context.

METHODS

82 healthy male participants underwent either transdermal testosterone (testosterone group) or placebo application (placebo group). Each participant performed a computerized stop-distance task before (T1) and 3.5h after (T2) treatment, during which they indicated how closely they would approach a human, animal or virtual character with varying emotional expression.

RESULTS

Men's PD towards humans and animals varied as a function of their emotional expression. In the testosterone group, a pre-post comparison indicated that the administration of 50mg testosterone was associated with a small but significant reduction of men's PD towards aggressive individuals. Men in the placebo group did not change the initially chosen PD after placebo application independent of the condition. However comparing the testosterone and placebo group after testosterone administration did not reveal significant differences. While the behavioral effect was small and only observed as within-group effect it was repeatedly and selectively shown for men's PD choices towards an angry woman, angry man and angry dog in the testosterone group. In line with the literature, our findings in young men support the influential role of exogenous testosterone on male's approach behavior during social confrontations.

The influence of androstadienone during psychosocial stress is modulated by gender, trait anxiety and subjective stress: An fMRI study

Androstadienone (ANDR), a bodily secreted steroid compound, is a socially relevant chemosignal that modulates subjective and (neuro)physiological responses, predominantly in females. The impact of ANDR on stress responses in males and females has not been explored. Therefore, this fMRI study aimed to examine psychosocial stress reactions induced by mental arithmetic and social evaluation on behavioral and hormonal levels (46 participants: 15 naturally cycling females in their early follicular phase (EF), 15 females on hormonal contraceptives (HC) and 16 males); and on a neural level (40 participants: 13 EF-females, 13 HC-females and 14 males) in an ANDR and placebo treatment repeated-measures design. While no gender differences emerged in subjective ratings and performance during stress, neural activation patterns differed significantly. Besides, ANDR attenuated the post-stress increase of negative mood in all participants. Region of interest analyses showed that irrespective of treatment, males showed stronger activation of the dorsolateral prefrontal cortex (DLPFC) than females. At the whole brain level, gender differences emerged indicating stronger fronto-parietal activation in males compared to HC-females on both treatments. Males showed stronger visual and fusiform activation than EF-females under ANDR. Both female groups did not show stronger activation than males. Further, error ratio in the ANDR-stress condition was positively associated with their post-stress cortisol level and increase in subjective stress in males; and male DLPFC activity in the ANDR-stress condition was negatively associated with trait anxiety. Surprisingly, compared to HC-females, EF-female only showed stronger activation of arousal-related areas under placebo treatment. Taken together, these findings suggest that the male stress reaction under social evaluative threat was stronger than female stress reactions as a function of ANDR. More specifically, this effect on behavioral and neural stress reactions seems to depend on trait anxiety in males only. The study highlights the significance of a chemosignal in enhancing social threat that may facilitate adaptive stress responses.

Conserved evolutionary history for quick detection of threatening faces

Humans quickly recognize threats such as snakes and threatening faces, suggesting that human ancestors evolved specialized visual systems to detect biologically relevant threat stimuli. Although non-human primates also detect snakes quickly, it is unclear whether primates share the efficient visual systems to process the threatening faces of their conspecifics. Primates may not necessarily process conspecific threats by facial expressions, because threats from conspecifics in natural situations are often accompanied by other cues such as threatening actions (or attacks) and vocal calls. Here, we show a similar threat superiority effect in both humans and macaque Japanese monkeys. In visual search tasks, monkeys and humans both responded to pictures of a threatening face of an unfamiliar adult male monkey among neutral faces faster than to pictures of a neutral face among threatening faces. However, the monkeys' response times to detect deviant pictures of a non-face stimulus were not slower when it was shown among threat faces than when it was shown among neutral faces. These results provide the first evidence that monkeys have an attentional bias toward the threatening faces of conspecifics and suggest that threatening faces are evolutionarily relevant fear stimuli. The subcortical visual systems in primates likely process not only snakes, but also more general biological threat-relevant stimuli, including threatening conspecific faces.

Regulation of nucleus accumbens transcript levels in mice by early-life social stress and cocaine

Much interest has been piqued regarding the quality of one's environment at early ages in modulating the susceptibility to drug addiction in adulthood. However, the molecular mechanisms that are engaged during early trauma and mediate the risk for drug addiction are poorly understood. In rodents, exposure to early-life stress alters the rewarding effects of cocaine, amphetamine, and morphine in adulthood. Recently, we demonstrated that the exposure of juvenile mice to social threat (Social Stress, S-S) promoted cocaine-seeking behavior and relapse of cocaine-seeking after periods of withdrawal, compared with unhandled controls (UN) and with juvenile mice that experienced only daily isolation in a novel environment (no social stress, NS-S). Interestingly, while the exposure to NS-S slightly increased cocaine-seeking behavior compared with UN, the same was not sufficient to promote cocaine reinstatement. In this study, we examined the long-term transcriptional changes that are induced by S-S compared to NS-S and linked the increased susceptibility of S-S mice to cocaine reinstatement. To this end, we performed genome-wide RNA sequencing analysis in the nucleus accumbens (NAC), which revealed that 89 transcripts were differentially expressed between S-S and NS-S mice. By Gene Ontology classification, these hits were enriched in genes that mediate cell proliferation, neuronal differentiation, and neuron/forebrain development. Eleven of these genes have been reported to be involved in substance use disorders, and the remaining genes are novel candidates in this area. We characterized 4 candidates with regard to their significant neurobiological relevance (ZIC1, ZIC2, FABP7, and PRDM12) and measured their expression in the NAC by immunohistochemistry. These findings provide insights into novel molecular mechanisms in NAC that might be associated with the risk of relapse in cocaine-dependent individuals.

The prosocial effects of 3,4-methylenedioxymethamphetamine (MDMA): Controlled studies in humans and laboratory animals

Users of ±3,4-methylenedioxymethamphetamine (MDMA; 'ecstasy') report prosocial effects such as sociability and empathy. Supporting these apparently unique social effects, data from controlled laboratory studies indicate that MDMA alters social feelings, information processing, and behavior in humans, and social behavior in rodents. Here, we review this growing body of evidence. In rodents, MDMA increases passive prosocial behavior (adjacent lying) and social reward while decreasing aggression, effects that may involve serotonin 1A receptor mediated oxytocin release interacting with vasopressin receptor 1A. In humans, MDMA increases plasma oxytocin and produces feelings of social affiliation. It decreases identification of negative facial expressions (cognitive empathy) and blunts responses to social rejection, while enhancing responses to others' positive emotions (emotional empathy) and increasing social approach. Thus, consistent with drug folklore, laboratory administration of MDMA robustly alters social processing in humans and increases social approach in humans and animals. Effects are consistent with increased sociability, with mixed evidence about enhanced empathy. These neurobiologically-complex prosocial effects likely motivate recreational ecstasy use.

Laughter as a social rejection cue: gelotophobia and transient cardiac responses to other persons' laughter and insult

Other persons' laughter, normally perceived as a signal that persons are friendly and inviting others to approach, can also be perceived as a cue of social rejection. In this study, prerecorded laughter was placed in a realistic and personally relevant context, and participants' responses were related to gelotophobia, a trait predisposing to perceiving laughter as a cue of social rejection. Individuals with gelotophobia showed marked heart rate deceleration in response to the laughter stimulus, possibly indicating a "freezing-like" response. Moreover, cardiac responses to anger provocation by overtly insulting statements indicated heightened aggressive anger in response to cumulated social threat. The study adds to recent research showing specific cardiac responses to social rejection and to the literature on social rejection sensitivity by demonstrating the value of using well interpretable physiological measures in this research context.

Self-compassion training modulates alpha-amylase, heart rate variability, and subjective responses to social evaluative threat in women

A growing body of research has revealed that social evaluative stressors trigger biological and psychological responses that in chronic forms have been linked to aging and disease. Recent research suggests that self-compassion may protect the self from typical defensive responses to evaluation. We investigated whether brief training in self-compassion moderated biopsychological responses to the Trier Social Stress Test (TSST) in women. Compared to attention (placebo) and no-training control conditions, brief self-compassion training diminished sympathetic (salivary alpha-amylase), cardiac parasympathetic, and subjective anxiety responses, though not HPA-axis (salivary cortisol) responses to the TSST. Self-compassion training also led to greater self-compassion under threat relative to the control groups. In that social stress pervades modern life, self-compassion represents a promising approach to diminishing its potentially negative psychological and biological effects.

Gender differences in neural-behavioral response to self-observation during a novel fMRI social stress task

The neural correlates of response to psychosocial stress and gender differences therein are difficult to model experimentally as this type of stressor is difficult to induce in a brain imaging environment. The Trier Social Stress Test (TSST), a behavioral paradigm that reliably induces moderate levels of stress was thus modified for the MRI environment. To determine the neurobehavioral basis of gender differences in response to observing oneself under social evaluative stress, 26 subjects (14 females) performed the TSST while being videotaped. During fMRI scanning, subjects were shown alternating video clips of two

CONDITIONS

SELF or a same-sex OTHER performing the TSST. Subjects rated their stress level immediately after the video clips. GENDER differences in the [SELF-OTHER] contrast were analyzed. There was a GENDER×CONDITION interaction such that only women reported increased subjective stress during video feedback of their TSST session. A whole brain analysis (SELF vs. OTHER) showed activation in the bilateral insula, inferior, middle and superior frontal gyri. Greater recruitment was seen among males in some of these same areas in the context of significantly lower stress ratings. Activation of areas involved in inhibitory control and sensory awareness might contribute to the significantly lower stress ratings in males. Understanding these gender differences is relevant to disorders of stress and self-concept.