Acute Psychological Stress Disrupts Attentional Bias to Threat-Related Stimuli

Perceived impacts of stressful events on train driver performance

Acute stress exposure can significantly impact a train driver's capacity to maintain safe train operations. However, research examining how train drivers perceive the impacts of acute stressors is limited. This study investigated train driver perceptions regarding performance impacts of stressful events and potential strategies for reducing negative impacts. 71 Australian train drivers were presented with three stressful event scenarios via an online survey and asked to rate the impacts on driving performance. Results showed that participants perceived that stress would enhance performance, but that impacts differed depending on the event type. The findings suggest that train drivers may not be subjectively aware of negative impacts of acute stress, which has important practical implications for risk management following an incident. Qualitative results revealed the most frequently reported stress impact related to cognition. Practical implications and future research directions to prevent and manage stressful event exposure are discussed.

The effects of yohimbine and hydrocortisone on selective attention to fearful faces: An fMRI study

INTRODUCTION

Selective attention to salient emotional information can enable an advantage in the face of danger. The present study aims to investigate the influence of the stress neuromodulators, norepinephrine and cortisol, on selective attention processes to fearful faces and its neuronal activation.

METHODS AND MATERIALS

We used a randomized, double-blind, placebo-controlled design. 167 healthy men between 18 and 35 years (mean [SD] age: 25.23 [4.24] years) participated in the study. Participants received either: (A) yohimbine (n= 41), (B) hydrocortisone (n = 41), (C) yohimbine and hydrocortisone (n = 42) or (D) placebo only (n= 43) and participated in a dot-probe task with fearful and neutral faces in an fMRI scanner.

RESULTS

We found an attentional bias toward fearful faces across all groups and related neuronal activation in the left cuneus. We did not find any differences between experimental treatment groups in selective attention and its neuronal activation.

DISCUSSION

Our results provide evidence that fearful faces lead to an attentional bias with related neuronal activation in the left cuneus. We did not replicate formerly reported activation in the amygdala, intraparietal sulcus, dorsal anterior cingulate cortex, and thalamus. Suitability of the dot-probe task for fMRI studies and insignificant treatment effects are discussed.

Understanding the effects of stress on the P300 response during naturalistic simulation of heights exposure

Stress is a prevalent bodily response universally experienced and significantly affects a person's mental and cognitive state. The P300 response is a commonly observed brain behaviour that provides insight into a person's cognitive state. Previous works have documented the effects of stress on the P300 behaviour; however, only a few have explored the performance in a mobile and naturalistic experimental setup. Our study examined the effects of stress on the human brain's P300 behaviour through a height exposure experiment that incorporates complex visual, vestibular, and proprioceptive stimuli. A more complex sensory environment could produce translatable findings toward real-world behaviour and benefit emerging technologies such as brain-computer interfaces. Seventeen participants experienced our experiment that elicited the stress response through physical and virtual height exposure. We found two unique groups within our participants that exhibited contrasting behavioural performance and P300 target reaction response when exposed to stressors (from walking at heights). One group performed worse when exposed to heights and exhibited a significant decrease in parietal P300 peak amplitude and increased beta and gamma power. On the other hand, the group less affected by stress exhibited a change in their N170 peak amplitude and alpha/mu rhythm desynchronisation. The findings of our study suggest that a more individualised approach to assessing a person's behaviour performance under stress can aid in understanding P300 performance when experiencing stress.

Exploring the possible relationship between skin microbiome and brain cognitive functions: a pilot EEG study

Human microbiota mainly resides on the skin and in the gut. Human gut microbiota can produce a variety of short chain fatty acids (SCFAs) that affect many physiological functions and most importantly modulate brain functions through the bidirectional gut-brain axis. Similarly, skin microorganisms also have identical metabolites of SCFAs reported to be involved in maintaining skin homeostasis. However, it remains unclear whether these SCFAs produced by skin bacteria can affect brain cognitive functions. In this study, we hypothesize that the brain's functional activities are associated with the skin bacterial population and examine the influence of local skin-bacterial growth on event-related potentials (ERPs) during an oddball task using EEG. Additionally, five machine learning (ML) methods were employed to discern the relationship between skin microbiota and cognitive functions. Twenty healthy subjects underwent three rounds of tests under different conditions-alcohol, glycerol, and water. Statistical tests confirmed a significant increase in bacterial population under water and glycerol conditions when compared to the alcohol condition. The metabolites of bacteria can turn phenol red from red-orange to yellow, confirming an increase in acidity. P3 amplitudes were significantly enhanced in response to only oddball stimulus at four channels (Fz, FCz, and Cz) and were observed after the removal of bacteria when compared with that under the water and glycerol manipulations. By using machine learning methods, we demonstrated that EEG features could be separated with a good accuracy (> 88%) after experimental manipulations. Our results suggest a relationship between skin microbiota and brain functions. We hope our findings motivate further study into the underlying mechanism. Ultimately, an understanding of the relationship between skin microbiota and brain functions can contribute to the treatment and intervention of diseases that link with this pathway.

Stress, working memory, and academic performance: a neuroscience perspective

The relationship between stress and working memory (WM) is crucial in determining students' academic performance, but the interaction between these factors is not yet fully understood. WM is a key cognitive function that is important for learning academic skills, such as reading, comprehension, problem-solving, and math. Stress may negatively affect cognition, including WM, via various mechanisms; these include the deleterious effect of glucocorticoids and catecholamines on the structure and function of brain regions that are key for WM, such as the prefrontal cortex and hippocampus. This review explores the mechanisms underlying how stress impacts WM and how it can decrease academic performance. It highlights the importance of implementing effective stress-management strategies to protect WM function and improve academic performance.

Toward objective characterizations of suicide risk: A narrative review of laboratory-based cognitive and behavioral tasks

Although suicide is a leading cause of preventable death worldwide, current prevention efforts have failed to substantively mitigate suicide risk. Suicide research has traditionally relied on subjective reports that may not accurately differentiate those at high versus minimal risk. This narrative review supports the inclusion of objective task-based measures in suicide research to complement existing subjective batteries. The article: 1) outlines risk factors proposed by contemporary theories of suicide and highlights recent empirical findings supporting these theories; 2) discusses ongoing challenges associated with current risk assessment tools and their ability to accurately evaluate risk factors; and 3) analyzes objective laboratory measures that can be implemented alongside traditional measures to enhance the precision of risk assessment. To illustrate the potential of these methods to improve our understanding of suicide risk, the article reviews how acute stress responses in a laboratory setting can be modeled, given that stress is a major precipitant for suicidal behavior. More precise risk assessment strategies can emerge if objective measures are implemented in conjunction with traditional subjective measures.

The power of (surreptitiously) mentioning your mentor's name: Subliminal priming of mentor's name modulates N170 responses to blurred faces

Using the event-related potentials (ERPs) technique and subliminal priming paradigm, the present study examined the influence of mentioning a mentor's name on graduate students. Fifty-eight graduate students were subliminally primed by mentor and stranger names before making pressure judgments of a series of unrelated blurred facial photos with neutral emotion. The face-sensitive N170 components were analyzed according to the pressure judgment × name prime conditions. The results showed that relative to stranger names, subliminal priming of mentor's name could modulate students' N170 reactions during facial processing. Specifically, the mentor-name priming attenuated N170 amplitudes for high-pressure judgment trials on the right hemisphere but heightened the overall N170 responses on the left hemisphere. Behavioral results also showed that the mentor-name priming slowed students' reaction time during pressure judgments; in addition, students' attitudes towards mentors were correlated with N170 amplitudes on high-pressure judgment conditions. These findings provided neuroscientific evidence demonstrating the psychological significance of mentors to graduate students. Theoretical and practical implications were also discussed.

(A lack of) effects of acute social stress on attentional bias to threat

Attentional biases toward or away from emotionally evocative stimuli have been well documented and are known to be clinically relevant, making it important to understand how various factors contribute to them. Some work has suggested that acute stress modulates attentional biases, but this work has produced inconsistent results. For example, many studies have found that stress enhances attentional bias, others that stress decreases attentional bias, and others still that there is no effect of stress at all. Methodological differences may explain these inconsistencies. For example, discrepancies exist between studies in participant sex (e.g., mixed sample vs. all men) and in the type of attentional bias paradigm. We addressed these gaps by examining the effects of an acute social stressor (vs. control) on attentional bias assessed via facial dot probe, focusing on potential sex differences in these effects (N = 141). We found that, overall, participants were significantly biased towards threat, but biases did not differ by stress condition or sex. These findings help to clarify the existing discrepancy in the literature, as we found that stress exerts little if any effect on attentional bias assessed via a facial dot probe.

Impact of acute psychosocial stress on attentional control in humans. A study of evoked potentials and pupillary response

Psychosocial stress has increased considerably in our modern lifestyle, affecting global mental health. Deficits in attentional control are cardinal features of stress disorders and pathological anxiety. Studies suggest that changes in the locus coeruleus-norepinephrine system could underlie the effects of stress on top-down attentional control. However, the impact of psychosocial stress on attentional processes and its underlying neural mechanisms are poorly understood. This study aims to investigate the effect of psychosocial stress on attentional processing and brain signatures. Evoked potentials and pupillary activity related to the oddball auditory paradigm were recorded before and after applying the Montreal Imaging Stress Task (MIST). Electrocardiogram (ECG), salivary cortisol, and subjective anxiety/stress levels were measured at different experimental periods. The control group experienced the same physical and cognitive effort but without the psychosocial stress component. The results showed that stressed subjects exhibited decreased P3a and P3b amplitude, pupil phasic response, and correct responses. On the other hand, they displayed an increase in Mismatch Negativity (MMN). N1 amplitude after MIST only decreased in the control group. We found that differences in P3b amplitude between the first and second oddball were significantly correlated with pupillary dilation and salivary cortisol levels. Our results suggest that under social-evaluative threat, basal activity of the coeruleus-norepinephrine system increases, enhancing alertness and decreasing voluntary attentional resources for the cognitive task. These findings contribute to understanding the neurobiological basis of attentional changes in pathologies associated with chronic psychosocial stress.

A meta-analysis of salivary cortisol responses in the Trier Social Stress Test to evaluate the effects of speech topics, sex, and sample size

Background

The Trier Social Stress Test (TSST) is one of the most widely used laboratory-based psychological stress paradigms. Previous studies have shown that males have a more robust cortisol response than females in the TSST. However, the effects of sample size, speech topic, and interaction between sex and speech topic on cortisol responses in TSST remain elusive. Our goal was to evaluate these influencing factors in the TSST using salivary cortisol reactivity as an objective measure.

Methods

We collected TSST research articles in Web of Science, PubMed, PsycNet, and CNKI. We only included TSST studies that had measures of salivary cortisol both before and after task completion. A total of 65 articles involving 76 sub-studies met our inclusion criteria, with a total of 5171 participants (2040 females and 3131 males). The effects of sample sizes were assessed to determine if results of studies with various sample sizes were stable. We performed multivariate meta-regression to determine the effects of speech topic, sex, and the interaction between sex and speech topic after controlling their confounding effects. Subgroup analysis of sex was conducted to detect inter-group differences. We further evaluated the baseline and peak salivary cortisol concentrations for males and females independently to detect the sources of sex differences.

Results

The average effect size (i.e., Cohen's d) of salivary cortisol reactivity was 0.93, 95% CI = 0.82 to 1.04, p < .001. The small studies produced larger variations in the reported effect sizes than the large-sample studies (r = -0.24, p = .041). A sample size of 40 was necessary to provide sufficient statistical power to detect significant changes of salivary cortisol in TSST. Speech topics, sex, and sex-speech topic interaction could predict salivary cortisol responses (F(df1 = 3, df2 = 72) = 11.98, p < .001) and explained 42.68% of the total experimental variation. Sex was the only significant contributing factor (p < .00025) in the regression model. Salivary cortisol responses in males were significantly higher than in females (Q_B = 42.89, df = 1, p < .001). Further, significant differences between males and females were detected at baseline (t = -2.03, df = 74, p = .046) and peak (t = -4.96, df = 74, p < .001).

Conclusions

The TSST effectively induces stress response as measured by salivary cortisol change. Forty samples is the minimum sample size for detecting the robust salivary cortisol responses. We confirmed that males have more robust salivary cortisol reactivity than females in TSST. Speech topics that we tested did not significantly contribute to differences in salivary cortisol responses. No significant interaction between sex and speech topic on salivary cortisol responses was detected.

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Forty samples is the minimum for detecting robust salivary cortisol responses.

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The speech topics tested did not significantly alter salivary cortisol responses.

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Males have higher salivary cortisol responses than females in the TSST.

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Males had higher salivary cortisol levels than females in the TSST at both baseline and peak.

Influence of acute stress on attentional bias toward threat: How a previous trauma exposure disrupts threat apprehension

While previous trauma exposure is known to be a risk factor for the development and maintenance of many psychological disorders, it remains unclear how it increases individual risk for prospective psychopathology in the aftermath of a new trauma exposure. The aim of this study was to investigate how a prior exposure to trauma affects attentional processing of threat before and after an acute stress task. Specifically, we assessed attentional biases to threat before and after a cold pressor task in 17 individuals who have been exposed to trauma (TE) compared to 18 individuals without trauma exposure (NTE). Behavioral results showed difficulties to disengage from threat in TE but not in the control group prior to stress induction, as well as a switch to an attentional bias toward threat after the cold pressor task in the TE group. For the ERPs, we highlighted (1) decreased N1 negativity in response to threatening stimuli after an acute stress in both groups, and (2) a parallel increase in P1 for such stimuli only in the TE group. Those results suggest a vulnerability presented by previously traumatized individuals when dealing with threats as well as an acute responsitity toward stress. Those results are interpreted in regards with the theorical models of stress and anxiety.

Effects of hydrocortisone and yohimbine on selective attention to emotional cues

INTRODUCTION

Facial expressions contain important affective information, and selective attention to facial expression provides an advantage in the face of loss, stress and danger. In addition, the sympathetic nervous system and hypothalamus-pituitary-adrenal axis mediate the organism's response to loss and danger. Here, we aimed at investigating the influence of sympathetic nervous system and hypothalamus-pituitary-adrenal axis activation on selective attention to affective facial stimuli.

METHODS AND MATERIALS

One hundred-and-four healthy men between 18-35 years old (mean (standard deviation) age: 24.1 (3.5) years) participated in the study. We used a randomised, double-blind, placebo-controlled design. Participants received either: (a) yohimbine, (b) hydrocortisone, (c) yohimbine and hydrocortisone or (d) placebo only and participated in a dot-probe task with sad, happy and neutral faces. We collected salivary samples to measure cortisol and alpha amylase activity in addition to measurements of blood pressure and heart rate. Salivary cortisol served as correlate of hypothalamus-pituitary-adrenal axis activation and salivary alpha amylase activity, blood pressure and heart rate as correlates of sympathetic nervous system activation. Measurements were carried out before and after drug administration.

RESULTS

We did not find a main effect or interaction effect of hydrocortisone or yohimbine administration on selective attention to happy faces. However, we found an interaction of yohimbine and hydrocortisone on selective attention to sad faces. Post-hoc t-test revealed an attentional bias away from sad stimuli and towards neutral faces in the hydrocortisone-only group.

DISCUSSION

Only hydrocortisone administration led to an attentional bias away from sad faces. Future studies should investigate these effects in major depression disorder, as this disorder is characterised by glucocorticoid resistance and increased processing of sad stimuli.

Stress effects on the oddball P300 and N2 in males and females

We examined the effect of psychosocial stress on electrophysiological markers of novelty and deviance processing, the N2 and P300, as well as sex differences therein. Participants underwent the Trier Social Stress Test (TSST) or a control procedure, followed by an oddball paradigm. A physiological stress response was induced in both sexes in the TSST condition. Furthermore, a reduced target P300 amplitude was elicited in the TSST condition in fronto-central electrodes, an effect that did not differ in magnitude between both sexes. By contrast, stressor effects on N2 amplitude differed by sex: In females, N2 amplitude was decreased in the TSST condition, while in males, no stress effects were observed. Exploratory correlational analyses suggested that a stress-induced P300 amplitude reduction, at least in males, could be due to a modulation of adrenergic activity. These results are consistent with sex differences in the manner in which stress affects lower-level, stimulus-driven vs. higher-level, more controlled processing stages.

The effects of acute stress and stress hormones on social cognition and behavior: Current state of research and future directions

Stress encompasses profound psychological and physiological changes that are observable on all levels, from cellular mechanisms, humoral changes, and brain activation to subjective experience and behavior. While the impact of stress on health has already been studied for decades, a more recent field of research has revealed effects of stress on human social cognition and behavior. Initial studies have attempted to elucidate the underlying biological mechanisms of these stress-induced effects by measuring physiological responses or by using pharmacological approaches. We provide an overview of the current state of research on the effects of acute stress induction or pharmacological manipulations of stress-related neuro circuitry on social cognition and behavior. Additionally, we discuss the methodological challenges that need to be addressed in order to gain further insight into this important research topic and facilitate replicability of results. Future directions may help to disentangle the complex interplay of psychological and biological stress variables and their effects on social cognition and behavior on health and in disorders with social deficits.

A systematic review of the Trier Social Stress Test methodology: Issues in promoting study comparison and replicable research

Since its development in 1993, the Trier Social Stress Test (TSST) has been used widely as a psychosocial stress paradigm to activate the sympathetic nervous system and hypothalamic-pituitary-adrenal axis (HPAA) stress systems, stimulating physiological functions (e.g. heart rate) and cortisol secretion. Several methodological variations introduced over the years have led the scientific community to question replication between studies. In this systematic review, we used the Preferred Reporting Items of Systematic Reviews and Meta-Analysis (PRISMA) to synthesize procedure-related data available about the TSST protocol to highlight commonalities and differences across studies. We noted significant discrepancies across studies in how researchers applied the TSST protocol. In particular, we highlight variations in testing procedures (e.g., number of judges, initial number in the arithmetic task, time of the collected saliva samples for cortisol) and discuss possible misinterpretation in comparing findings from studies failing to control for variables or using a modified version from the original protocol. Further, we recommend that researchers use a standardized background questionnaire when using the TSST to identify factors that may influence physiological measurements in tandem with a summary of this review as a protocol guide. More systematic implementation and detailed reporting of TSST methodology will promote study replication, optimize comparison of findings, and foster an informed understanding of factors affecting responses to social stressors in healthy people and those with pathological conditions.

Acute Psychosocial Stress Modulates the Detection Sensitivity for Facial Emotions

Abstract. Psychosocial stress has been shown to alter social perception and behavior. In the present study, we investigated whether a standardized psychosocial stressor modulates the perceptual sensitivity for positive and negative facial emotions and the tendency to allocate attention to facial expressions. Fifty-four male participants underwent the Trier Social Stress Test for Groups (TSST-G) or a nonstressful control condition before they performed a facial emotions detection task and a facial dot-probe task to assess attention for positive and negative facial expressions. Saliva samples were collected over the course of the experiment to measure free cortisol and alpha amylase. In response to the TSST-G, participants showed marked increases in subjective stress, salivary cortisol, and alpha amylase compared to the control condition. In the control condition, detection performance was higher for angry compared to happy facial expressions, while in the stressful condition this difference was reversed. Here, participants were more sensitive to happy compared to angry facial expressions. Attention was unaffected by psychosocial stress. The results suggest that psychosocial stress shifts social perception in terms of detection sensitivity for facial expressions toward positive social cues, a pattern that is consistent with the tendency to seek social support for coping with stress.

Attentional blink affected by acute stress in women: The role of affective stimuli and attentional resources

The role of attentional resources and affective stimuli on temporal selective attention in the rapid serial visual presentation (RSVP) paradigm under acute stress was explored among women. Seventy-three female undergraduates were randomly assigned to the Trier Social Stress Test (TSST) group or control group. We found that when the first target was negative, stress increased its accuracy. Stress promoted the recognition of neutral target two (T2) only at lag2, and there was no interaction with theemotionality of target one (T1). In addition, the accumulated effect of stress enhanced temporal selective attention, predominately 20-40 min after the TSST task; cortisol concentration during this time period could significantly predict AB task performance. In summary, when attentional resources were severely insufficient, individuals under stress were more able to focus on the current target; that is, stress facilitated selective attention. A novel result was that participants were exempt from the affective influence of previous targets, which may have been caused by activation of the autonomic nervous system and gender differences.