Effects of positive and negative affect on electromyographic activity over zygomaticus major and corrugator supercilii

Pleasant stimuli typically elicit greater electromyographic (EMG) activity over zygomaticus major and less activity over corrugator supercilii than do unpleasant stimuli. To provide a systematic comparison of these 2 measures, the authors examined the relative form and strength of affective influences on activity over zygomaticus major and corrugator supercilii. Self-reported positive and negative affective reactions and facial EMG were collected as women (n = 68) were exposed to series of affective pictures, sounds, and words. Consistent with speculations based on known properties of the neurophysiology of the facial musculature, results revealed a stronger linear effect of valence on activity over corrugator supercilii versus zygomaticus major. In addition, positive and negative affect ratings indicated that positive and negative affect have reciprocal effects on activity over corrugator supercilii, but not zygomaticus major.     

Respiratory sinus arrhythmia is associated with trait positive affect and positive emotional expressivity

The associations among respiratory sinus arrhythmia (RSA), trait positive affect and positive emotional expressivity were investigated in the present study. Physiological data were collected from 98 college students during baseline and fear film-viewing and recovery periods in the lab, and their affectivity data were collected three times (immediately before, 4 months after and 12 months after the physiological data collection) using the Positive and Negative Affect Schedule (PANAS) and Emotional Expressivity Scale. The results showed that trait positive affect was stably associated with baseline RSA independently of trait negative affect. Positive emotional expressivity was also stably associated with baseline RSA independently of negative emotional expressivity. Neither trait affect nor emotional expressivity was associated with RSA reactivity or RSA rebound. These findings suggest that baseline vagal tone might be the parasympathetic correlate of individuals with a positive emotional style.     

Salivary alpha‐amylase changes promoted by sustained exposure to affective pictures

We studied the changes in salivary alpha‐amylase (sAA) and other psychophysiological indices (heart rate, skin conductance, and corrugator supercilii activity) elicited by sustained exposure to affective pictures. Thirty‐nine subjects viewed five blocks of pictures depicting mutilations, human attack, neutral scenes, sport/adventure, and erotica. Each block comprised 12 pictures of the same content. Saliva samples were collected before and after each block of pictures. The results showed that mutilation pictures promoted the greatest increase in sAA activity and output, as well as greater corrugator supercilii activity than pleasant pictures. Skin conductance response did not differ among high arousal picture contents. Changes in sAA varied with the affective valence but not with the arousal ratings of the pictures. Our results point to sAA as an index directly related to the unpleasantness elicited by sustained exposure to affective stimuli.     

Emotional and physiological responses to normative and idiographic positive stimuli in bipolar disorder

Background

Few studies have examined differences in emotional responding among distinct types of positive stimuli. This is important to understand both for individuals characterized by extreme positive mood (i.e., bipolar disorder) and healthy adults.

Methods

Using a multi-method within-subjects design, the current study examined physiological, behavioral, and self-reported responses to normative (film) and idiographic (memory) happy stimuli in bipolar (BD; n = 25) and healthy control groups (CTL; n = 23).

Results

For both groups, the happy films were associated with greater self-reported and behavioral displays of positive emotion compared to the happy memory. Furthermore, the BD group displayed greater cardiac vagal tone - a putative marker of positive emotion - across both the film and memory.

Conclusion

Normative stimuli were more potent elicitors of positive emotion compared to idiographic stimuli. The study provided further evidence for cardiac vagal tone as a potential biomarker of extreme positive emotion in BD.     

Exposure to acute stress is associated with attenuated sweet taste

This study examined the effects of stress on taste perception. Participants (N = 38; 21 women) completed two laboratory sessions: one stress (public speaking, math, and cold pressor) and one control rest session. The taste perception test was conducted at the end of each session and included rating the intensity and pleasantness of sweet, salty, sour, and savory solutions at suprathreshold concentrations. Cardiovascular, hormonal, and mood measures were collected throughout the sessions. Participants showed the expected changes in cardiovascular, hormonal, and mood measures in response to stress. Reported intensity of the sweet solution was significantly lower on the stress day than on the rest day. Cortisol level poststress predicted reduced intensity of salt and sour, suggesting that stress‐related changes in adrenocortical activity were related to reduced taste intensity. Results indicate that acute stress may alter taste perception, and ongoing research investigates the extent to which these changes mediate effects of stress on appetite.     

Blood‐stage Plasmodium berghei infection leads to short‐lived parasite‐associated antigen presentation by dendritic cells

Despite extensive evidence that Plasmodium species are capable of stimulating the immune system, the association of malaria with a higher incidence of other infectious diseases and reduced responses to vaccination against unrelated pathogens suggests the existence of immune suppression. Recently, we provided evidence that blood‐stage Plasmodium berghei infection leads to suppression of MHC class I‐restricted immunity to third party (non‐malarial) antigens as a consequence of systemic DC activation. This earlier study did not, however, determine whether reactivity was also impaired to MHC class II‐restricted third party antigens or to Plasmodium antigens themselves. Here, we show that while P. berghei‐expressed antigens were presented early in infection, there was a rapid decline in presentation within 4 days, paralleling impairment in MHC class I‐ and II‐restricted presentation of third party antigens. This provides important evidence that P. berghei not only causes immunosuppression to subsequently encountered third party antigens, but also rapidly limits the capacity to generate effective parasite‐specific immunity.     

Unconfounding the Hassles Scale: External sources versus internal responses to stress

The Hassles Scale (HS; Kanner, A. D., et al., J. Behav. Med.4:1–39,1981) has aroused considerable debate. Its authors and some others report that it provides a superior way of operationalizing psychosocial stress and that it predicts health outcomes as well as or better than measures of major life events. Critics contend that the HS is confounded by an inability to separate the external, objective sources of stress from the internal, subjective reactions to it and that it measures, rather than predicts, psychological distress. In this article we argue that a careful distinction between the two major HS summary scores, Hassle Number and Hassle Intensity, will largely disentangle the confound. Results based on data collected from a sample of alcohol and substance abusers (N=630) suggest that the number of external stressors and the strength of internal reactions to them can be separately assessed using the HS. Results indicate that these two components are independently as well as jointly associated with psychological distress.Research funded in part by the Nalco Foundation, Oak Brook, Illinois.     

Decreased reaction time variability is associated with greater cardiovascular responses to acute stress

Cardiovascular (CV) responses to mental stress are prospectively associated with poor CV outcomes. The association between CV responses to mental stress and reaction times (RTs) in aging individuals may be important but warrants further investigation. The present study assessed RTs to examine associations with CV responses to mental stress in healthy, older individuals using robust regression techniques. Participants were 262 men and women (mean age = 63.3 ± 5.5 years) from the Whitehall II cohort who completed a RT task (Stroop) and underwent acute mental stress (mirror tracing) to elicit CV responses. Blood pressure, heart rate, and heart rate variability were measured at baseline, during acute stress, and through a 75‐min recovery. RT measures were generated from an ex‐Gaussian distribution that yielded three predictors: mu‐RT, sigma‐RT, and tau‐RT, the mean, standard deviation, and mean of the exponential component of the normal distribution, respectively. Decreased intraindividual RT variability was marginally associated with greater systolic (B = ?.009, SE = .005, p = .09) and diastolic (B = ?.004, SE = .002, p = .08) blood pressure reactivity. Decreased intraindividual RT variability was associated with impaired systolic blood pressure recovery (B = ?.007, SE = .003, p = .03) and impaired vagal tone (B = ?.0047, SE = .0024, p = .045). Study findings offer tentative support for an association between RTs and CV responses. Despite small effect sizes and associations not consistent across predictors, these data may point to a link between intrinsic neuronal plasticity and CV responses.     

Error‐related electromyographic activity over the corrugator supercilii is associated with neural performance monitoring

Emerging research in social and affective neuroscience has implicated a role for affect and motivation in performance monitoring and cognitive control. No study, however, has investigated whether facial electromyography (EMG) over the corrugator supercilii—a measure associated with negative affect and the exertion of effort—is related to neural performance monitoring. Here, we explored these potential relationships by simultaneously measuring the error‐related negativity, error positivity (Pe), and facial EMG over the corrugator supercilii muscle during a punished, inhibitory control task. We found evidence for increased facial EMG activity over the corrugator immediately following error responses, and this activity was related to the Pe for both between‐ and within‐subject analyses. These results are consistent with the idea that early, avoidance‐motivated processes are associated with performance monitoring, and that such processes may also be related to orienting toward errors, the emergence of error awareness, or both.     

Neuropeptide S receptor gene is associated with cortisol responses to social stress in humans

The neuropeptide S (NPS) and its receptor NPSR represent a transmitter system critically involved in the modulation of anxiety and arousal in rodents. Initial human studies indicate that the T-allele of the functional NPSR gene (NPSR1) polymorphism (rs324981), which increases NPS potency at NPSR, is associated with anxiety-related phenotypes. Since stress is critically involved in the pathogenesis of anxiety disorders, we tested the association between rs324981 and stress reactivity in 196 healthy males. Participants were exposed to the Trier Social Stress Test for Groups (TSST-G), a standardized laboratory protocol for stress exposure in a group format. Salivary cortisol and subjective stress responses were assessed. A significant genotype by time interaction and a main effect of genotype were shown, with T-allele carriers displaying larger cortisol and subjective stress responses. This is the first report to show involvement of the NPS system in the regulation of the neuroendocrine stress response in humans.     

Associations of objectively measured physical activity with daily mood ratings and psychophysiological stress responses in women

The aim of this study was to examine associations of objectively measured physical activity with daily mood ratings and psychophysiological stress responses. We recruited 40 healthy females (aged 28.7 ± 6.1 yrs) who completed a once-a-day mood rating scale for 7 days, along with a 7-day assessment of physical activity using accelerometers and psychophysiological stress testing. The findings suggest that levels of physical activity as measured using an accelerometer are associated with both depressive symptoms over the past 2 weeks (CES-D) (r = - .33, p = .038) and with daily positive emotional style (r = .49, p = .001). The relationship between physical activity and positive emotional style remained after controlling for age, body mass index, and negative emotional style (t = 3.31, p = .002). Physical activity was not related to any psychophysiological stress responses.     

Autonomic nervous system reactivity to positive and negative mood induction: the role of acute psychological responses and frontal electrocortical activity

The differential effects of positive versus negative emotions on autonomic nervous system activity are insufficiently understood. This study examined the role of acute mood responses and central nervous system activity on heart rate variability (HRV) using 5-min event recall tasks (happiness and anger recall) and a 5-min Stroop Color Word Test (SCWT) in 20 healthy individuals (mean age 25 ± 4 years, 55% female). HRV was measured in high frequency (HF) and low frequency (LF) domains, and frontal brain activity using electroencephalography (EEG) in the alpha frequency band in F3 and F4. Happiness Recall resulted in increased LF-HRV (p = 0.005) but not HF-HRV (p = 0.71). Anger Recall did not change HRV (p-values > 0.10). The SCWT produced decreases in HF-HRV (p = 0.001) as well as LF-HRV (p = 0.001). The magnitude of feeling “happy” during Happiness Recall was positively correlated with ΔHF-HRV (p = 0.050), whereas an incongruent mood state (“frustrated”) was associated with smaller ΔHF-HRV (p = 0.070). Associations between frontal EEG activation and HRV responses were mostly non-significant, except for increased right frontal activation during Happiness Recall which was associated with a decrease in LF/HF ratio (p = 0.009). It is concluded that positive and negative mood induction result in differential HRV responses, which is related to both task valence and the intensity of task-induced emotions.     

Positive affect is associated with cardiovascular reactivity, norepinephrine level, and morning rise in salivary cortisol

Positive affect was examined as a predictor of (1) cardiovascular reactivity during a sadness and an anger recall task and recovery following the protocol, (2) epinephrine (EPI) and norepinephrine (NOREPI) reactivity and level during the recall protocol, and (3) the diurnal pattern of salivary cortisol. Sample was 328 individuals. Negative affect, age, race, sex, smoking status, income, and BMI were adjusted. During sadness recall, positive affect was inversely related to systolic blood pressure ( p =.007) and diastolic blood pressure ( p =.049) reactivity, and unrelated to heart rate ( p =.226). Positive affect was unrelated to reactivity during anger recall ( p s>.19), and was unrelated to recovery at the end of the recall protocol. Positive affect was inversely related to the mean level of NOREPI ( p =.046), and unrelated to EPI ( p =.149). Positive affect was inversely related to the increase in cortisol 30 min post awakening ( p =.042), and unrelated to the evening decline in cortisol levels ( p =.174). Positive emotions may be relevant to good health.     

Early life stress and psychiatric disorder modulate cortical responses to affective stimuli

Altered affective processing has been proposed as mediating between early life stress (ELS) and subsequent psychopathology. The present study examined whether ELS influences affective cortical processing differently in psychiatric patients and healthy subjects. The number of stressful experiences before onset of puberty was assessed in 50 inpatients with diagnoses of Major Depressive Disorder, schizophrenia, drug addiction, or Borderline Personality Disorder and in 20 healthy comparison subjects. Subjects monitored pleasant, neutral, and unpleasant pictures during magnetoencephalographic recording. Suppression of right-posterior activity 160–210 ms after stimulus onset was associated with certain diagnoses and high ELS. Results confirmed specific contributions of ELS versus adult stress, comorbid posttraumatic stress disorder, or depression.     

Eye movement and electrodermal responses to threat stimuli in post-traumatic stress disorder

A core feature of post-traumatic stress disorder (PTSD) is hypervigilence to threatening material. This study measured processing of threat material in PTSD with simultaneously acquired initial eye movements and electrodermal activity, following presentation of threatening and neutral words. Ten PTSD subjects and 10 controls were presented with 4 words in parafoveal range. On trials in which a threat word was present, PTSD subjects demonstrated initial eye fixations on the threat word more than controls. PTSD subjects also demonstrated more orienting responses on all trials than controls. These results suggest that processing of threat information in PTSD can be usefully investigated with convergent psychophysiological methodologies.     

Patient-centered interviewing is associated with decreased responses to painful stimuli: An initial fMRI study

Objective

To identify the functional magnetic resonance imaging (fMRI) changes associated with a patient-centered interview (PCI) and a positive provider–patient relationship (PPR).

Methods

Nine female patients participated, five randomly selected to undergo a replicable, evidence-based PCI, the other four receiving standard clinician-centered interviews (CCI). To verify that PCI differed from CCI, we rated the interviews and administered a patient satisfaction with the provider–patient relationship (PPR) questionnaire. Patients were then scanned as they received painful stimulation while viewing pictures of the interviewing doctor and control images (unknown doctor).

Results

Interview ratings and questionnaire results confirmed that PCIs and CCIs were performed as planned and PCIs led to a much more positive PPR. We found significantly reduced pain-related neural activation in the left anterior insula region in the PCI group when the interviewing doctor's picture was shown.

Conclusion

This study identifies an association between a PCI that produced a positive PPR and reduced pain-related neural responses in the anterior insula. This is an initial step in understanding the neural underpinnings of a PCI.

Practice implications

If confirmed, our results indicate one neurobiological underpinning of an effective PCI, providing an additional scientific rationale for its use clinically.     

Interoceptive accuracy is related to long‐term stress via self‐regulation

Interoception describes the ability to perceive internal bodily signals. Previous research found a relationship between interoceptive accuracy (IAcc) and cardiovascular outcomes during or after acute stress. So far, the association between IAcc and long‐term stress has not been investigated, although this would be important to identify a starting point to prevent long‐term stress. To address this idea in the current study, we examined the relationship between IAcc and long‐term stress, which was assessed with different questionnaires and biological markers, including cortisol and dehydroepiandrosterone (DHEA). Furthermore, we investigated self‐regulation as a mechanism linking IAcc to long‐term stress. The sample consisted of 98 participants. To measure IAcc, participants completed the heartbeat perception task. Perceived long‐term stress and self‐regulation were assessed via an online questionnaire. Moreover, hair samples were taken from 65 participants to determine long‐term stress with cortisol and DHEA as well as the ratio of both. Results showed that IAcc was positively related to DHEA and weakly negatively related to the other indicators of long‐term stress, except for the nonsignificant relationships to the indicators cortisol and stress experiences due to negative events. Furthermore, these relationships were mediated by participants' enhanced self‐regulation. Thus, our results suggest that enhanced self‐regulation could be a mechanism explaining why IAcc is associated with long‐term stress.     

Perceived stress is associated with smaller hippocampal volume in adolescence

Perceived stress has been associated with decreased hippocampal, amygdala, and prefrontal cortex volume, as well as decreased memory and executive functioning performance in adulthood. Parents' perceived stress has been linked to decreased hippocampal volume in young children. However, no studies have investigated the links between self‐perceived stress and brain structure or function in adolescents. Additionally, findings from previous research with younger or older samples are inconsistent, likely in part due to inconsistencies in participants' age range. In this study, we investigated the associations among self‐perceived stress, family socioeconomic factors (family income, parental education), subcortical (hippocampus, amygdala) volumes, prefrontal cortical thickness and surface area, and memory and executive functioning performance in adolescents. One hundred and forty‐three participants (12–20 years old) were administered a cognitive battery, a questionnaire to assess perceived stress, and a structural MRI scan. Higher levels of perceived stress were associated with decreased adolescent hippocampal volume. This study provides empirical evidence of how experience may shape brain development in adolescence—a period of plasticity during which it may be possible to intervene and prevent negative developmental outcomes.     

Sex differences in interleukin‐6 stress responses in people with Type 2 diabetes

People with Type 2 diabetes (T2D) show dysregulated inflammatory responses to acute stress, but the effect of sex on inflammatory responses in T2D remains unclear. The purpose of this study was to investigate differences in interleukin (IL)‐6 stress responses between older men and women with T2D. One hundred and twenty‐one people (76 men; mean age = 64.09, SD = 7.35, 45 women; mean age = 63.20, SD = 6.70) with doctor‐verified T2D took part in this laboratory‐based stress testing study. Participants carried out acute mental stress tasks, and blood was sampled at baseline, immediately poststress, 45 min poststress, and 75 min poststress to detect plasma IL‐6 concentrations. IL‐6 change scores were computed as the difference between the baseline measurement and the three time points poststress. Main effects and interactions were tested using mixed model analysis of covariance. We found a significant main effect of time on IL‐6 levels, and a significant Sex × Time interaction. In adjusted analyses including the three change scores and all the covariates, the significant Sex × Time interaction was maintained; IL‐6 responses were greater in women at 45 and 75 min poststress compared with men, adjusting for age, body mass index, smoking, household income, glycated hemoglobin, oral antidiabetic medication, insulin/other injectable antidiabetic medication, depressive symptoms, and time of day of testing. Different inflammatory stress response pathways are present in men and women with T2D, with women producing larger IL‐6 increases. The long‐term implications of these differences need to be elucidated in future studies.     

High perceived stress in relation to life events is associated with blunted cardiac reactivity

The current study examined whether the perception of life stress related to cardiovascular reactivity. Participants (n = 100) completed the Perceived Stress Scale, the Undergraduate Stress Questionnaire, and undertook a standard mental arithmetic stress task. Blood pressure and pulse rate were measured at baseline, during, and following stress task exposure. Reactivity was the difference between stress and baseline cardiovascular activity. A perceived stress difference score (PSDS) was calculated by subtracting the Undergraduate Stress Questionnaire scores from the Perceived Stress Scale scores. Two groups were created: high PSDS (n = 15; PSDS at least 1 SD above the mean) and low PSDS (n = 15; PSDS at least 1 SD below the mean). There was a significant difference between groups in pulse rate reactivity, F(1,28) = 8.73, p = .006, η² = .24. High PSDS scores were associated with significantly lower pulse rate reactions to stress. Those who perceived their lives as more stressful than their actual stress exposures justified would appear to be characterised by blunted cardiac reactivity.