The Influence of Neuroticism on the Muscle Response in the Trapezius and Frontalis Muscles to Anticipatory Stress

Objective quantification of mental stress in the workplace would be beneficial for designing work tasks to avoid the negative consequences of mental stress. Methods such as surface electromyography have proven to be sensitive to mental demands. However, there is little knowledge about the muscle response and moderating factors during anticipatory stress paradigms. This study examined whether the personality dimension neuroticism moderates the muscle response to the expectation of an unpredictable electrical shock. Forty-seven subjects underwent three expectation phases, in which they could expect a pleasant audio signal (NoShock) or an electric shock in two conditions (anticipation of the first: Shock1, and second electric shock: Shock2) at an unpredictable moment. The frontalis muscle activity and the upper and upper/middle parts of the trapezius muscle were recorded using surface electromyography. Neuroticism was surveyed using the Big Five Inventory to assign the subjects to a group with lower or higher neuroticism. Shock1 only induced higher trapezius muscle activity in the higher neuroticism group, which vanished during Shock2, while the frontalis muscle showed no significant effects. The results suggest that neuroticism should be considered a moderating factor in assessing anticipatory stress using surface electromyography at the trapezius muscle.

In Identifying the Source of the Incongruent Effect

Emotional signals from the face and body are normally perceived as an integrated whole in everyday life. Previous studies have revealed an incongruent effect which refers to distinctive behavioral and neural responses to emotionally congruent versus incongruent face-body compounds. However, it remains unknown which kind of the face-body compounds caused the incongruence effect. In the present study, we added neutral face and neutral body stimuli to form new face-body compounds. Forty subjects with normal or corrected-to-normal vision participated in this experiment. By comparing the face-body compounds with emotional conflict and face-body compounds with neutral stimuli, we could investigate the source of the incongruent effect. For both behavioral and event-related potential (ERP) data, a 2 (bodily expression: happiness, fear) × 2 (congruence: congruent, incongruent) repeated-measure analysis of variance (ANOVA) was performed to re-investigate the incongruent effect and a 3 (facial expression: fearful, happy, neutral) × 3 (bodily expression: fearful, happy, neutral) repeated-measure ANOVA was performed to clarify the source of the incongruent effect. As expected, both behavioral and ERP results have successfully repeated the incongruent effect. Specifically, the behavioral data showed that emotionally congruent versus incongruent face-body compounds were recognized more accurately ( p < .05). The ERP component of N2 was modulated by the emotional congruency between the facial and bodily expression showing that the emotionally incongruent compounds elicited greater N2 amplitudes than emotionally congruent compounds ( p < .05). No incongruent effect was found for P1 or P3 component ( p = .079, p = .99, respectively). Furthermore, by comparing the emotionally incongruent pairs with the neutral baseline, the present study suggests that the source of the incongruent effect might be from the happy face-fearful body compounds. We speculate that the emotion expressed by the fearful body was much more intensive than the emotion expressed by the happy body and thus caused a stronger interference in judging the facial expressions.

Cardiovascular and Self-Reported Recovery in Two-Shift Systems

Recovery is necessary to maintain workers’ health and efficiency. Shift work has been associated with delayed recovery processes. The objective of this study was to examine the cardiovascular and self-reported recovery measures of German shift and day workers in the hotel and catering industry. Furthermore, it aimed to clarify to what extent shift groups differentiate given additional factors that influence recovery (ability to relax, lifestyle). The sample group consisted of 64 alternative shift workers (two-shift system with a low proportion of night work) and 96-day workers employed in the hotel and catering industry. Blood pressure monitoring was conducted for 24 hr during a working day, including the phases of work, leisure, and sleep, to assess cardiovascular reduction during leisure and sleep. The blood pressure status was measured over the course of a 4-day self-assessment period. Self-reported measures, including quality of sleep (Pittsburgh Sleep Quality Index, PSQI), work-life balance (WPC), ability to relax (FABA), and lifestyle factors (physical activity, smoking, drinking), were assessed through questionnaires. Sixty-one participants (36%) were hypertensives. There were no significant effects of cardiovascular recovery regarding the reduction of blood pressure for the calculated differences between WORK – LEISURE, WORK – SLEEP, and LEISURE – SLEEP among shift and day workers. Shift workers reported a significantly less favorable work-life balance ( p = .017), a decreased ability to relax ( p = .001), and less regular physical activity ( p = .003). The workload within the two-shift system of the hotel and catering industry seems to have a lesser effect on cardiovascular means than on self-reported measures of recovery. The decisive factor is the ability to relax, which means psychological detachment from work. To enable a comprehensive recovery, an optimally designed recovery cycle is necessary for shift systems.

Somatosensory Deviance Detection ERPs and Their Relationship to Analogous Auditory ERPs and Interoceptive Accuracy

Automatic deviance detection has been widely explored in terms of mismatch responses (mismatch negativity or mismatch response) and P3a components of event-related potentials (ERPs) under a predictive coding framework; however, the somatosensory mismatch response has been investigated less often regarding the different types of changes than its auditory counterpart. It is not known whether the deviance detection responses from different modalities correlate, reflecting a general prediction error mechanism of the central nervous system. Furthermore, interoceptive functions have been associated with predictive coding theory, but whether interoceptive accuracy correlates with deviance detection brain responses has rarely been investigated. Here, we measured ERPs to changes in somatosensory stimuli’s location and intensity and in sound intensity in healthy adults ( n = 34). Interoceptive accuracy was measured with a heartbeat discrimination task, where participants indicated whether their heartbeats were simultaneous or non-simultaneous with sound stimuli. We found a mismatch response and a P3a response to somatosensory location and auditory intensity changes, but for somatosensory intensity changes, only a P3a response was found. Unexpectedly, there were neither correlations between the somatosensory location deviance and intensity deviance brain responses nor between auditory and somatosensory brain responses. In addition, the brain responses did not correlate with interoceptive accuracy. The results suggest that although deviance detection in the auditory and somatosensory modalities are likely based on similar neural mechanisms at a cellular level, their ERP indexes do not indicate a linear association in sensitivity for deviance detection between the modalities. Furthermore, although sensory deviance detection and interoceptive detection are both associated with predictive coding functions, under these experimental settings, functional relationships were not observed. These results should be taken into account in the future development of theories related to human sensory functions and in extensions of the predictive coding theory in particular.

Insular Cortex Response to Static Visual Sexual Stimuli

According to previous research, the insula is important for processing salient and emotional stimuli, but its precise role remains elusive. By combining high spatial and temporal resolution, intracranial electroencephalography (iEEG) might contribute to filling this gap. Four drug-resistant epileptic patients with intracranial electrodes in the insula were instructed to watch and rate pictures with sexual content and neutral pictures. Event-related potentials (ERPs) were computed separately for both types of stimuli. Ninety-three percent of the anterior insula (AI) and 85% of the posterior insula (PI) contacts showed differences between ERPs. AI-positive deflections tended to have an earlier onset than PI-positive deflections. The results suggest that the AI generates a P300-like response and contributes to the early phase of the late positive potential, both components found enhanced while viewing emotional stimuli in the ERP literature. The present findings are interpreted as congruent with the role of the AI in maintaining attention to salient stimuli.

Test-Retest Reliability of Event-Related Potentials Across Three Tasks

Event-related potentials (ERPs) constitute a useful and cost-effective method to assess the neural underpinnings of multiple cognitive processes. ERPs have been used to track changes in cognitive processes in longitudinal and clinical studies. However, few studies have assessed their test-retest reliability (i.e., their consistency across time). Therefore, in the current study, we aimed to assess the test-retest reliability of ERPs (P100, N100, P200, N200, P3b, lateralized readiness potentials) across three tasks. In two assessments separated by approximately 4 months, ERPs were recorded in 26 healthy participants, during two oddball tasks (motor and counting) and a stimulus-response compatibility paradigm. Pearson’s correlations and intraclass correlations were used to assess the test-retest reliability of ERPs. Correlations between ERPs elicited by the three tasks were assessed with Pearson’s correlations. Our analyses revealed moderate to very strong test-retest reliability for most ERP components across the three tasks. Test-retest reliability did not differ between the motor and counting oddball tasks. Most ERPs were also correlated across paradigms. Therefore, these results confirm that ERPs have the potential to be reliable markers to serve as robust assessment tools in longitudinal or clinical studies.

Emotional Distraction by Constant Finger Tapping

This study examined the effects of emotional distraction in the context of recalling stressful interpersonal events in daily life. Previous studies have revealed that distraction decreases unpleasant emotions. In this study, we examined whether distraction tasks decrease unpleasant task-related thoughts in addition to unpleasant emotions. Furthermore, to investigate the implicit effects of emotional changes, we examined changes in pupil size in relation to unpleasant emotions and task-unrelated thoughts (TUT). The behavioral tasks were administered to 21 university students ( Mage = 21.24 ± 2.93 years; range: 18–30 years). After excluding participants for poor data quality, 16 (21.31 ± 3.34 years; 18–30 years) were included for further pupil data analysis. As an emotion induction procedure, participants were asked to freely recall memories of stressful interpersonal events in their daily lives and were given a series of questions about their recalled memories, which were presented on the monitor. In the following distraction experiment, questions during the emotion induction procedure were represented as emotional stimulation; a distraction task (non-constant or constant finger tapping) or rest condition was then performed; subsequently, ratings were given for attentional state, thought types conceived during the tasks, and emotional state. Upon analysis, differences in the ratings for unpleasant emotion and TUT were non-significant between all conditions. Nevertheless, pupil dilation in the non-constant and constant conditions was associated with decreased unpleasant emotions ( p < .05; p < .05 to .01). More importantly, pupil dilation was associated with decreased unpleasant TUT ( p < .05) only in the constant condition. Although the observed effects were subtle, we found that constant finger tapping decreased unpleasant emotions and TUT. It is expected for a future emotion regulation study to further investigate the effects in the relationships among emotions, thoughts, and physiological states, which can help in coping with unpleasant emotions.

Chinese Classical Dancers Have Improved Spontaneous Activity in Visual Brain Areas

Resting-state functional magnetic resonance imaging (fMRI) studies demonstrate that long-term exercise or dance training may cause changes in brain structure and function. However, the changes of neurofunction in the long-term practitioners of Chinese classical dance are still unclear. The purpose of the study is to explore the neurofunctional alterations associated with long-term Chinese classical dance training. Thirty female college students were selected, 15 students majoring in Chinese classical dance (average training years = 9.73 ± 1.75 years) and 15 education-matched non-dancer students with no previous experience of regular dance training. In this cross-sectional design, the resting-state fMRI data were acquired only once to observe the structural and functional changes of the brain. Compared with non-dancers, professional dancers had no significant difference in the total volume of whole brain, gray matter, white matter, and cerebrospinal fluid. While in professional dancers, we found increased amplitude of low-frequency fluctuation (ALFF) in the left superior occipital gyrus, right Cuneus, and left calcarine fissure and surrounding cortex (Calcarine); increased fractional ALFF and regional homogeneity in the right Calcarine, indicating the increase of spontaneous brain activity in these brain areas. Since these brain areas are related to visual cognitive function, the results suggest that long-term Chinese classical dance training is associated with increased spontaneous regional brain activity in the visual areas. This may be closely related to the specific characteristics of Chinese classical dance and long-term professional training.

Cognitive Workload in an Auditory Digit Span Task When Memory Span Is in the Neighborhood of Seven Items

Task performance of digit span has been widely used in the research on human short-term memory. The present study was conducted to show that the dynamic change of underlying mental effort can be further estimated by measuring the strength of theta oscillations at a forehead site on the scalp. Fourteen healthy adults ( Mage = 26.1 years) performed a passive listening (PL) task and an auditory digit span (DS) task, and electroencephalography (EEG) data were recorded simultaneously during the two tasks. Considering that the digit span paradigm has often been conducted in a non-laboratory location, the EEG data were collected with a wireless single-channel headset system. The headset system was validated in this study by replicating the EEG (an enhancement of frontal theta power) as well as event-related potential (N200 and P300) responses to the deviant tone stimuli in the PL task. The outcomes of the DS task showed that the memory span of the participants was at least eight items. Moreover, frontal theta power in response to a list of six to eight digits increased significantly. This pattern of results supports a hypothesis that additional mental effort is required for short-term retention of verbal items when the number of stimulus items exceeds the newly proposed limit of short-term memory capacity. Some strengths and limitations of the current EEG headset system are also discussed.

Self-Reported Emotion Regulation Is Associated With Response to Test of Cardiac Vagal Function

Parasympathetic function and emotional self-regulation (ESR) share neuroanatomic structures. Based on Porges’ Polyvagal Theory and the Neurovisceral Integration Model (NIM), we compared vagally mediated heart-rate variability (vmHRV) with psychometrically assessed ESR. We hypothesized that vmHRV and ESR would be associated during rest, a vagal function test, and recovery from that test. A significant association would justify the psychometric measuring of parasympathetic health, which is less burdensome than its psychophysiological assessment. Two hundred thirteen healthy males (aged: 18–26 years, M = 20.29 years) took part in the present study. They completed the Emotion Regulation Questionnaire (ERQ) and underwent the Cold Face Test (CFT) for 4 min wearing ambulatory electrocardiograms. A High frequency (HF) band was used as a measure of vmHRV before, during, and after the CFT. Associations between the HF band and ESR were analyzed with partial rank correlations. There was no significant association between ERQ scores and the response to the CFT itself. But there was an almost significant association between the ERQ scale Cognitive Appraisal and baseline vmHRV, and a significant association between Cognitive Appraisal and cardiac recovery from the CFT, that is, participants with higher scores on that ESR scale revealed a tendency to exhibit greater vmHRV during baseline and they exhibited greater vagal withdrawal during recovery from the CFT. Cognitive appraisal as a psychometrically assessed emotion regulatory process was reflected in a more flexible parasympathetic activity (i.e., better cardiac vagal health) during recovery from an exclusively physiological stressor. This lends convergent validity to self-reported emotion regulation, and justification for its use as a measure of ESR as a trait, offering further support for the Polyvagal Theory and NIM.