Impaired free recall of neutral but not negative material tested 105 min after cortisol administration

Pharmacological studies have consistently shown memory retrieval impairment after administration of cortisol, particularly pronounced for emotional laboratory material (i.e. list of emotional words). However, it is unclear how pharmacological elevation of cortisol affects memory retrieval of ecologically-relevant emotional material (i.e. similar to a newspaper article about an emotional event). In the present study, we aimed to explore whether cortisol administration affects the recall of ecologically-relevant emotional and neutral material, and when memory retrieval occurs after a longer delay (105 min). In this double-blind, pseudo-randomized, placebo-control study, 79 participants learned a negative text and a neutral text. Twenty-four hours later, they were administrated either 10 mg of hydrocortisone or placebo. After 105 min, participants engaged in free recall of both texts. The group with cortisol administration showed significantly reduced free recall compared to the placebo group. Interestingly, this memory retrieval impairment was driven by significantly lower recall after cortisol vs. placebo administration for neutral texts, but not negative texts. The current finding suggests that cortisol administration impairs neutral ecologically-relevant material while leaving emotional material unaffected. These divergent findings, compared to existing literature, emphasize the necessity of employing more ecologically validated material to gain a more comprehensive understanding of the intricate interplay between cortisol administration and memory for ecological material.

Opposite effects of emotion and event segmentation on temporal order memory and object-context binding

Our daily lives unfold continuously, yet our memories are organised into distinct events, situated in a specific context of space and time, and chunked when this context changes (at event boundaries). Previous research showed that this process, termed event segmentation, enhances object-context binding but impairs temporal order memory. Physiologically, peaks in pupil dilation index event segmentation, similar to emotion-induced bursts of autonomic arousal. Emotional arousal also modulates object-context binding and temporal order memory. Yet, these two critical factors have not been systematically studied together. To address this gap, we ran a behavioural experiment using a paradigm validated to study event segmentation and extended it with emotion manipulation. During encoding, we sequentially presented greyscale objects embedded in coloured frames (colour changes defining events), with a neutral or aversive sound. During retrieval, we tested participants' memory of temporal order memory and object-colour binding. We found opposite effects of emotion and event segmentation on episodic memory. While event segmentation enhanced object-context binding, emotion impaired it. On the contrary, event segmentation impaired temporal order memory, but emotion enhanced it. These findings increase our understanding of episodic memory organisation in laboratory settings, and potentially in real life with perceptual changes and emotion fluctuations constantly interacting.

Tackling childbirth-related intrusive memories with a single-session behavioural intervention involving a visuospatial task: protocol for a single-blind, waitlist-controlled randomised trial

INTRODUCTION

Approximately 12.3% of mothers experience childbirth-related post-traumatic stress symptoms (CB-PTSS). However, evidence-based interventions to treat CB-PTSS are lacking. Intrusive memories (IM), a key CB-PTSS, are distressing and can trigger other PTSS by reliving the traumatic event. Emerging evidence shows that a behavioural intervention involving a visuospatial task (BI-VT) can reduce the number of IM and PTSS, supposedly by interfering with the reconsolidation of the trauma memory. This study aims to test the efficacy of a single-session BI-VT targeting IM to reduce the number of childbirth-related (CB-)IM and PTSS, in comparison to a waitlist control group (WCG).

METHODS AND ANALYSIS

In this multicentre, single-blind, randomised controlled trial being undertaken at one regional and one university hospital in Switzerland, 60 participants will be allocated to the Immediate Intervention Group (IIG), receiving the immediate intervention on day 15, and 60 participants to the WCG receiving the delayed intervention on day 30. All participants will report their CB-IM during the 2 weeks preimmediate and postimmediate intervention in diaries. The IIG will additionally report their CB-IM over weeks 5 and 6 postimmediate intervention. Self-report questionnaires will assess CB-PTSS at 2 weeks preimmediate and postimmediate intervention in both groups, and at 6 weeks postimmediate intervention in the IIG. A feedback questionnaire will evaluate the intervention acceptability. The primary outcome will be group differences in the number of CB-IM between the 2 weeks preimmediate and postimmediate intervention. Secondary outcomes will be CB-PTSS at 2 and 6 weeks postimmediate intervention, the number of CB-IM at weeks 5 and 6 postimmediate intervention, and intervention acceptability.

ETHICS AND DISSEMINATION

Ethical approval was granted by the Human Research Ethics Committee of the Canton of Vaud (study number 202200652). Participants will provide an informed consent before study participation. Results will be presented in peer-reviewed journals and at conferences.

TRIAL REGISTRATION NUMBER

NCT05381155.

Adult age differences in the psychophysiological response to acute stress

Age-related differences in the psychophysiology of the acute stress response are poorly understood given the limited number of studies and the high heterogeneity of findings. The present study contributes by investigating age differences in both the psychological and physiological responses to acute stress in a sample of healthy younger (N = 50; 18-30; M_age = 23.06; SD = 2.90) and older adults (N = 50; 65-84; M_age = 71.12; SD = 5.02). Specifically, the effects of psychosocial stress (i.e., age-adapted Trier Social Stress Test) were investigated at numerous timepoints throughout the stress response phases (i.e., baseline, anticipation, reactivity, recovery) on cortisol, heart rate, subjective stress, and anticipatory appraisal of the stressful situation. The study was conducted in a between-subject (younger vs. older) cross-over (stress vs. control) design. Results revealed age-related differences in both physiological and psychological variables: older adults had overall lower salivary cortisol levels in the stress and control conditions and lower stress-induced cortisol increase (i.e., AUCi). In addition, older adults' cortisol reactivity was delayed compared to younger adults. Older adults showed a lower heart rate response in the stress condition while no age differences were observed in the control condition. Finally, older adults reported less subjective stress and a less negative stress appraisal during the anticipation phase than younger adults, which could potentially explain lower physiological reactivity in this age group. Results are discussed in relation to the existing literature, potential underlying mechanisms, and future directions for the field.

Pharmacologically increased cortisol levels impair recall of associative background context memory in males, but not females

Laboratory studies have consistently shown that stress impairs memory retrieval of individual parts (items) of a memory. The stress-hormone cortisol has been particularly linked to this impairment. However, it is unclear whether cortisol similarly affects the binding of items to associative context information in memory, i.e. the constituents of episodic memory. Here, we examine memory retrieval of item and associative memory under pharmacologically elevated cortisol vs. normal levels. Given that previous studies have indicated potential sex differences in the stress- and cortisol-induced memory modulation, we additionally assessed whether there may be sex differences for the cortisol effect on memory retrieval. Eighty-four female and male participants were tested in a placebo controlled, double-blind between-subject design, assigned to either a cortisol (10 mg hydrocortisone) or a placebo group. Participants of both groups were presented foreground images of negative and neutral valence on different neutral background scenes. Twenty-four hours later, participants' memory for the images and their associated background scene was tested with a recognition task 20 min after substance administration. Among the 78 participants of both groups included in the final analysis, cortisol levels were higher in the cortisol group in comparison to the placebo group, and female participants had higher cortisol levels after hydrocortisone intake in comparison to male participants. Item memory did not differ between the placebo and cortisol group. In contrast, in males, but not females, associative memory for the background scene of emotional foreground images was lower in the cortisol vs. placebo group. Moreover, the individual cortisol increase during the recognition task was negatively correlated to memory for the background scenes of the emotional foreground images only in male participants of the cortisol group. This study shows that pharmacologically increased cortisol levels distinctly affect associative memory in female and male participants, but have no effect on item memory, indicating a complex interaction for the stress effects on memory.

In Older Adults, Perceived Stress and Self-Efficacy Are Associated with Verbal Fluency, Reasoning, and Prospective Memory (Moderated by Socioeconomic Position)

Despite evidence that stress relates negatively to cognitive functioning in older adults, little is known how appraisal of stress and socioeconomic meso-level factors influence different types of cognitive functions in older adults. Here, we assess the relationship between perceived stress (PSS scale) and a battery of cognitive functions, including prospective memory in 1054 older adults (65+). A moderator analysis assessed whether this relationship varies with neighborhood socioeconomic status using an area-based measure of Socioeconomic Position (SEP). Perceived stress was associated with worse processing speed, verbal fluency, and inductive reasoning. The perceived self-efficacy subscale of the PSS is related to better performance in these measures. Higher self-efficacy was also associated with better prospective memory; this relationship was more pronounced for people with high neighborhood SEP. These findings indicate that not only do perceived stress and perceived self-efficacy relate to cognitive functioning in older age but also that neighborhood SEP is a moderator of this relationship.

The relation of low cognitive abilities to low well-being in old age is attenuated in individuals with greater cognitive reserve and greater social capital accumulated over the life course

Objectives: The present study sets out to investigate the relation of cognitive abilities to well-being and its interplay with key life course proxies of cognitive reserve and social capital in a large sample of older adults.Method: Three thousand eighty older adults served as sample for the present study. Physical well-being (EuroQoL-5D questionnaire) and psychological well-being (Satisfaction with Life Scale) as well as cognitive performance in terms of verbal abilities (Mill Hill vocabulary scale), processing speed (Trail Making Test part A), and cognitive flexibility (Trail Making Test part B) were assessed. Participants reported information on education, occupation, cognitively stimulating leisure activities, the different languages regularly spoken as well as family and close friends.Results: Moderation analyses showed that the relation of cognitive performance to physical and psychological well-being was significantly attenuated in individuals with a higher cognitive level of the first job after education, a larger number of midlife and current cognitively stimulating leisure activities, a larger number of languages regularly spoken, a larger number of significant family members and friends, and more frequent contact with and more confidence in significant family members.Conclusion: Present data suggest that the relation of low cognitive abilities to low well-being in old age is attenuated in individuals with greater cognitive reserve and greater social capital accumulated over the life course.

Better memory for intrinsic versus extrinsic details underlies the enhanced recollective experience of negative events

Why we remember emotional events with an increased subjective sense of remembering (SSR) is unclear. SSR for neutral events is linked to memory for various kinds of details. Using the Remember/Know paradigm, participants provided written justifications of their Remember responses indicating what they specifically recollected about a negative or neutral photo seen during encoding. Crucially, Remember responses for negative photos were more often linked to memory for details of the stimuli (intrinsic details) versus details related to external associations (extrinsic details) or emotional reaction at encoding, suggesting that memory for intrinsic details underlies the enhanced SSR of negative stimuli.

Cortisol suppression after memory reactivation impairs later memory performance

Experiencing stressful or traumatic events can result in disabling clinical symptoms of maladaptive emotional memory retrieval, which are only partly addressed by the currently proposed treatments. Cortisol modulation has been shown to affect emotional memory retrieval and potentially reconsolidation, offering an opportunity for developing more efficient treatments for disorders with an emotional memory component. Here, we investigated if cortisol suppression after reactivation of emotional memories weakens later memory thereof. Forty healthy young men were tested in a randomized, placebo controlled, double-blind, and between-subject design, assigned either to a cortisol suppression (metyrapone) group or a placebo group. Participants of both groups, were presented with two emotional stories at an encoding session (Day 1). One of the two stories was later reactivated and followed by metyrapone vs. placebo administration (Day 3). Memory for both stories was tested at a recognition memory session (Day 7). In the group undergoing cortisol suppression after memory reactivation memory performance was weaker compared to the placebo group, tested four days after reactivation. This study shows that cortisol suppression can weaken memory for past events, possibly by altering reconsolidation processes and thus exerting long-lasting weakening effects on the original memory.

The Longitudinal Relationship of Perceived Stress Predicting Subsequent Decline in Executive Functioning in Old Age Is Attenuated in Individuals with Greater Cognitive Reserve

BACKGROUND

Cognitively stimulating activities contribute to the accumulation of cognitive reserve that is proposed to be instrumental for maintaining cognitive functioning in aging. Adopting a novel, more general conceptual perspective including models of vulnerability, we argue that cognitive reserve may modify the longitudinal association between perceived stress and the rate of subsequent decline in executive functioning.

OBJECTIVE

The present study set out to investigate the longitudinal relationship between perceived stress and subsequent decline in executive functioning over 6 years as measured through performance changes in the Trail Making Test (TMT) and whether this longitudinal relationship differed by key markers of cognitive reserve (education, occupation, and leisure activities), taking into account age, sex, and chronic diseases as covariates.

METHODS

We used latent change score modeling based on longitudinal data from 897 older adults tested on TMT parts A and B in two waves 6 years apart. Mean age in the first wave was 74.33 years. Participants reported information on perceived stress, education, occupation, leisure activities, and chronic diseases.

RESULTS

The longitudinal relationship between greater perceived stress in the first wave of data collection and steeper subsequent decline in executive functioning over 6 years was significantly reduced in individuals who had pursued a higher frequency of leisure activities in the first wave.

CONCLUSION

The longitudinal relationship between perceived stress and subsequent decline in executive functioning may be attenuated in individuals who have accumulated greater cognitive reserve through an engaged lifestyle. Implications for current cognitive reserve and gerontological research are discussed.

Cognitive Reserve and Social Capital Accrued in Early and Midlife Moderate the Relation of Psychological Stress to Cognitive Performance in Old Age

AIMS

The present study set out to investigate the relation of psychological stress to cognitive performance and its interplay with key life course markers of cognitive reserve and social capital in a large sample of older adults.

METHODS

We assessed cognitive performance (verbal abilities and processing speed) and psychological stress in 2,812 older adults. The Participants reported information on education, occupation, leisure activities, family, and close friends.

RESULTS

Greater psychological stress was significantly related to lower performance in verbal abilities and processing speed. Moderation analyses suggested that the relations of psychological stress to cognitive performance were reduced in individuals with higher education, a higher cognitive level of the first profession practiced after education, a larger number of midlife leisure activities, a larger number of significant family members, and a larger number of close friends.

CONCLUSION

Cognitive reserve and social capital accrued in early and midlife may reduce the detrimental influences of psychological stress on cognitive functioning in old age.

Suppressing but not intensifying emotion decreases arousal and subjective sense of recollection

Emotional memories are commonly recalled with an increased subjective sense of recollection but not necessarily with more accurate context recollection, depending on the type of context. Response-focused emotion regulation techniques, such as suppressing and intensifying emotion expression, can alter subjective arousal and later memory and confidence about memory. Here, we investigated if emotion suppression affects later subjective sense of recollection as well as context recollection for different types of details. To disentangle the contribution of arousal modulation versus potential cognitive costs of emotion suppression effects on later subjective sense of recollection, we further explored if intensifying emotion expression similarly affects later subjective sense of recollection and actual context recollection as emotion suppression. We found that emotion suppression decreases the subjective sense of recollection, while intensifying emotion expression has no effect on the subjective sense of recollection. In contrast, suppressing emotion did not affect the recollection of extrinsic and intrinsic contextual details, while intensifying emotion expression decreased recollection of intrinsic item features of emotional scenes. In conclusion, response-focused emotion regulation techniques with distinct effects on subjective arousal differentially affect the subjective sense of recollection and memory for contextual details. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Suppressing cortisol at encoding reduces the emotional enhancement in subjective sense of recollection

The stress hormone cortisol, released when encountering an emotional event, contributes to form a strong emotional memory. Such emotionally arousing memories are recalled with an enhanced subjective sense of recollection, i.e. experienced in memory as more vivid and richer in details. We examined here whether cortisol plays a role in this emotional enhancement in subjective sense of recollection for a set of learned scenes. Suppressing cortisol at encoding decreased the emotional enhancement in subjective sense of recollection at a test 28 h later, but did not affect familiarity and memory for a contextual detail. Individual cortisol levels were significantly correlated to emotional enhancement in subjective sense of recollection. These findings indicate that cortisol plays a modulatory role for enhanced subjective sense of recollection for emotional events.

Emotional brain states carry over and enhance future memory formation

Emotional arousal can produce lasting, vivid memories for emotional experiences, but little is known about whether emotion can prospectively enhance memory formation for temporally distant information. One mechanism that may support prospective memory enhancements is the carry-over of emotional brain states that influence subsequent neutral experiences. Here we found that neutral stimuli encountered by human subjects 9-33 min after exposure to emotionally arousing stimuli had greater levels of recollection during delayed memory testing compared to those studied before emotional and after neutral stimulus exposure. Moreover, multiple measures of emotion-related brain activity showed evidence of reinstatement during subsequent periods of neutral stimulus encoding. Both slow neural fluctuations (low-frequency connectivity) and transient, stimulus-evoked activity predictive of trial-by-trial memory formation present during emotional encoding were reinstated during subsequent neutral encoding. These results indicate that neural measures of an emotional experience can persist in time and bias how new, unrelated information is encoded and recollected.

Beta-adrenergic Blockade at Memory Encoding, but Not Retrieval, Decreases the Subjective Sense of Recollection

Humans remember emotional events not only better but also exhibit a qualitatively distinct recollective experience-that is, emotion intensifies the subjective vividness of the memory, the sense of reliving the event, and confidence in the accuracy of the memory [Phelps, E. A., & Sharot, T. How (and why) emotion enhances the subjective sense of recollection. Current Directions in Psychological Science, 17, 147-152, 2008]. Although it has been demonstrated that activation of the beta-adrenergic system, linked to increases in stress hormone levels and physiological arousal, mediates enhanced emotional memory accuracy, the mechanism underlying the increased subjective sense of recollection is unknown. Behavioral evidence suggests that increased arousal associated with emotional events, either at encoding or retrieval, underlies their increased subjective sense of recollection. Using a double-blind, placebo-controlled, within-subject design, we showed that reducing arousal at encoding through oral intake of 80-mg of the beta-adrenergic receptor antagonist propranolol decreases the subjective sense of recollection for both negative and neutral stimuli 24 hr later. In contrast, administration of propranolol before memory retrieval did not alter the subjective sense of recollection. These results suggest that the neurohormonal changes underlying increased arousal at the time of memory formation, rather than the time of memory retrieval, modulate the subjective sense of recollection.

Blocking mineralocorticoid receptors impairs, blocking glucocorticoid receptors enhances memory retrieval in humans

Memory retrieval is impaired at very low as well as very high cortisol levels, but not at intermediate levels. This inverted-U-shaped relationship between cortisol levels and memory retrieval may originate from different roles of the mineralocorticoid (MR) and glucocorticoid receptor (GR) that bind cortisol with distinctly different affinity. Here, we examined the role of MRs and GRs in human memory retrieval using specific receptor antagonists. In two double-blind within-subject, cross-over designed studies, young healthy men were asked to retrieve emotional and neutral texts and pictures (learnt 3 days earlier) between 0745 and 0915 hours in the morning, either after administration of 400 mg of the MR blocker spironolactone vs placebo (200 mg at 2300 hours and 200 mg at 0400 hours, Study I) or after administration of the GR blocker mifepristone vs placebo (200 mg at 2300 hours, Study II). Blockade of MRs impaired free recall of both texts and pictures particularly for emotional material. In contrast, blockade of GRs resulted in better memory retrieval for pictures, with the effect being more pronounced for neutral than emotional materials. These findings indicate indeed opposing roles of MRs and GRs in memory retrieval, with optimal retrieval at intermediate cortisol levels likely mediated by high MR but concurrently low GR activation.

Memory for time and place contributes to enhanced confidence in memories for emotional events

Emotion strengthens the subjective sense of remembering. However, these confidently remembered emotional memories have not been found be more accurate for some types of contextual details. We investigated whether the subjective sense of recollecting negative stimuli is coupled with enhanced memory accuracy for three specific types of central contextual details using the remember/know paradigm and confidence ratings. Our results indicate that the subjective sense of remembering is indeed coupled with better recollection of spatial location and temporal context, but not higher memory accuracy for colored dots placed in the conceptual center of negative and neutral scenes. These findings show that the enhanced subjective recollective experience for negative stimuli reliably indicates objective recollection for spatial location and temporal context, but not for other types of details, whereas for neutral stimuli, the subjective sense of remembering is coupled with all the types of details assessed. Translating this finding to flashbulb memories, we found that, over time, more participants correctly remembered the location where they learned about the terrorist attacks on 9/11 than any other canonical feature. Likewise, participants' confidence was higher in their memory for location versus other canonical features. These findings indicate that the strong recollective experience of a negative event corresponds to an accurate memory for some kinds of contextual details but not for other kinds. This discrepancy provides further evidence that the subjective sense of remembering negative events is driven by a different mechanism than the subjective sense of remembering neutral events.

Emotion enhances the subjective feeling of remembering, despite lower accuracy for contextual details

Emotion strengthens the subjective experience of recollection. However, these vivid and confidently remembered emotional memories may not necessarily be more accurate. We investigated whether the subjective sense of recollection for negative stimuli is coupled with enhanced memory accuracy for contextual details using the remember/know paradigm. Our results indicate a double-dissociation between the subjective feeling of remembering, and the objective memory accuracy for details of negative and neutral scenes. "Remember" judgments were boosted for negative relative to neutral scenes. In contrast, memory for contextual details and associative binding was worse for negative compared to neutral scenes given a "remember" response. These findings show that the enhanced subjective recollective experience for negative stimuli does not reliably indicate greater objective recollection, at least of the details tested, and thus may be driven by a different mechanism than the subjective recollective experience for neutral stimuli.

Melatonin improves memory acquisition under stress independent of stress hormone release

RATIONALE

Animal studies suggest that the pineal hormone melatonin influences basal stress hormone levels and dampens hormone reactivity to stress.

OBJECTIVES

We investigated whether melatonin also has a suppressive effect on stress-induced catecholamine and cortisol release in humans. As stress hormones affect memory processing, we further examined a possible accompanying modulation of memory function.

MATERIALS AND METHODS

Fifty healthy young men received a single oral dose of either 3 mg melatonin (n = 27) or placebo medication (n = 23). One hour later, they were exposed to a standardized psychosocial laboratory stressor (Trier Social Stress Test). During stress, subjects encoded objects distributed in the test room, for which memory was assessed a day later ("memory encoding under stress"). Fifteen minutes following stress, memory retrieval for words learnt the day before was tested ("memory retrieval after stress"). Plasma epinephrine and norepinephrine levels, salivary free cortisol levels and psychological responses (attention, wakefulness) were repeatedly measured before and after stress exposure.

RESULTS

Melatonin specifically enhanced recognition memory accuracy of objects encoded under stress (p < 0.001). In contrast, 15 min after stress, when cortisol levels were highest, retrieval of memories acquired the day before was not influenced by melatonin. Moreover, melatonin did not influence stress-induced elevation of catecholamine and cortisol levels which in turn did not correlate with the effects of melatonin on memory.

CONCLUSIONS

The findings point to a primary action of melatonin on central nervous stimulus processing under conditions of stress and possibly on memory consolidation and exclude any substantial suppressive action of the substance on hormonal stress responses.

The level of physical activity affects adrenal and cardiovascular reactivity to psychosocial stress

Physical activity plays a key role in the control of neuroendocrine, autonomic, and behavioral responses to physical and psychosocial stress. However, little is known about how the level of physical activity modulates stress responsiveness. Here, we test whether different levels of physical activity are associated with different adrenal, cardiovascular, and psychological responses to psychosocial stress. In addition, competitiveness is assessed as a personality trait that possibly modulates the relationship between physical activity and stress reactivity. Eighteen elite sportsmen, 50 amateur sportsmen, and 24 untrained men were exposed to a standardized psychosocial laboratory stressor (Trier Social Stress Test). Repeated measures of salivary free cortisol, heart rate, and psychological responses to psychosocial stress were compared among the 3 study groups. Elite sportsmen exhibited significantly lower cortisol, heart rate, and state anxiety responses compared with untrained subjects. Amateur sportsmen showed a dissociation between sympathetic and hypothalamic-pituitary-adrenal responsiveness to stress, with significantly reduced heart rate responses but no difference in cortisol responses compared with untrained men. Different levels of competitiveness among groups did not mediate stress reactivity. Our results are in line with previous studies indicating reduced reactivity of the autonomic nervous system to psychosocial stress in trained individuals. More importantly, these findings imply a differential effect of the level of physical activity on different stress-related neurophysiological systems in response to psychosocial stress.

Higher overcommitment to work is associated with lower norepinephrine secretion before and after acute psychosocial stress in men

BACKGROUND

Overcommitment (OC) is a pattern of excessive striving. In reaction to work stress, OC has been associated with higher sympathetic nervous system activation and cortisol release, but data on neuroendocrine reactivity to standardized stressors are scarce. We investigated whether OC is associated with differential levels of the stress hormones norepinephrine and cortisol in response to acute psychosocial stress.

METHODS

Fifty-eight medication-free non-smoking men aged between 20 and 65 years (mean+/-S.E.M.: 36.3+/-1.8) underwent an acute standardized psychosocial stress task combining public speaking and mental arithmetic in front of an audience. We assessed OC as well as a variety of psychological control variables including vital exhaustion, perfectionism, chronic stress, and cognitive stress appraisal. Moreover, we measured plasma norepinephrine as well as salivary cortisol before and after stress and several times up to 60 min thereafter.

RESULTS

Higher OC was associated with lower baseline norepinephrine levels (r = -0.37, p < 0.01). General linear models controlling for age, BMI, and mean arterial blood pressure revealed that higher overcommitment was associated with lower norepinephrine and cortisol levels before and after stress (p's < 0.02) as well as with lower norepinephrine stress reactivity (p = 0.02). Additional controlling for the potential psychological confounders vital exhaustion, perfectionism, chronic stress, and depression confirmed lower norepinephrine levels before and after stress (p < 0.01) as well lower norepinephrine stress reactivity (p = 0.02) with increasing OC. Higher OC independently explained 13% of the total norepinephrine stress response (beta = -0.46, p < 0.01, R(2) change = 0.13).

CONCLUSIONS

Our findings suggest blunted increases in norepinephrine following stress with increasing OC potentially mirroring blunted stress reactivity of the sympathetic nervous system.

Trained men show lower cortisol, heart rate and psychological responses to psychosocial stress compared with untrained men

Physical activity has proven benefits for physical and psychological well-being and is associated with reduced responsiveness to physical stress. However, it is not clear to what extent physical activity also modulates the responsiveness to psychosocial stress. The purpose of this study was to evaluate whether the reduced responsiveness to physical stressors that has been observed in trained men can be generalized to the modulation of physiological and psychological responses to a psychosocial stressor. Twenty-two trained men (elite sportsmen) and 22 healthy untrained men were exposed to a standardized psychosocial laboratory stressor (Trier Social Stress Test). Adrenocortical (salivary free cortisol levels), autonomic (heart rate), and psychological responses (mood, calmness, anxiety) were repeatedly measured before and after stress exposure. In response to the stressor, cortisol levels and heart rate were significantly increased in both groups, without any baseline differences between groups. However, trained men exhibited significantly lower cortisol and heart rate responses to the stressor compared with untrained men. In addition, trained men showed significantly higher calmness and better mood, and a trend toward lower state anxiety during the stress protocol. On the whole, elite sportsmen showed reduced reactivity to the psychosocial stressor, characterized by lower adrenocortical, autonomic, and psychological stress responses. These results suggest that physical activity may provide a protective effect against stress-related disorders.

The spatial extent of lateral interactions in flicker perception

We investigated the influence of the relative phase of a temporally modulated annulus on the perceived flicker strength of a center stimulus having the same temporal modulation. These measurements were performed in two subjects at two temporal frequencies and with different outer diameters of the annulus. The perceived flicker strength was strongly modulated by the phase difference between center and surround stimulus. This modulation depended on the size of the annulus. In the absence of an annulus the perceived flicker strength was not modulated. The modulation initially increased with increasing annulus size and reached a plateau. The space constant of the function describing the modulation as a function of annulus size was about 0.5 degrees and is similar to the sizes of receptive field surrounds of subcortical cells. This finding is in favor of the hypothesis that the physiological basis of the perceived flicker strength in the center stimulus is present already at a subcortical level.

Acute stress impairs recognition for positive words--association with stress-induced cortisol secretion

Some studies suggest that stress-induced effects of cortisol on memory are modulated by the valence of the stimuli to be learned and retrieved. The present study investigated the effect of acute stress-induced cortisol secretion on acquisition and retrieval of pleasant, unpleasant and neutral words. Sixty healthy men were randomly assigned to one of the three experimental groups. Participants were either exposed to a standardized laboratory stressor (the Trier Social Stress Test) before learning a wordlist, or before retrieval, or were not stressed. Free recall and recognition were tested 24 h later. Free recall was not affected by stress exposure. For recognition, there was no main effect of the stressor, but a main effect of valence and a valence by group interaction emerged: recognition for positive words was significantly impaired when subjects were stressed before retrieval. In addition, a positive correlation between the cortisol response and errors of commission was found. The results suggest that acute stress impairs memory for positive stimuli and that stress-induced cortisol secretion interferes with accuracy of memory retrieval, i.e. the ability to discriminate true memories from false ones.

Cortisol has different effects on human memory for emotional and neutral stimuli

Adrenal stress hormones are considered to play a role in memory enhancement of emotionally arousing events. To investigate the effects of cortisol on human emotional memory, subjects were administered hydrocortisone (25 mg) or placebo and presented with either an emotionally arousing or a neutral story. Memory for the story was tested 1 week later. In all memory tests, subjects who viewed the emotional story scored better for the emotionally arousing story parts, indicating that arousal enhances memory. In memory of details, cortisol showed an interaction with story valence but no main effect: cortisol enhanced memory for details of the neutral story version, but impaired memory for details of the emotionally arousing version. We thus confirm a non-linear interaction between cortisol and arousal on memory formation.