Psychophysiological effects of walking in forests and urban built environments with disparate road traffic noise exposure: study protocol of a randomized controlled trial.

BACKGROUND: Stress is a widespread phenomenon and reality of everyday life, entailing negative consequences for physical and psychological wellbeing. Previous studies have indicated that exposure to greenspaces and nature-based interventions are promising approaches to reducing stress and promoting restoration. However, an increasing percentage of the population lives in urban regions with limited opportunities to spend time in greenspaces. In addition, urban settings typically feature increased levels of noise, which represents a major environmental stressor. Although various studies have compared the effects of exposure to greenspaces versus urban built environments, evidence of the effects of noise in this context is very limited. Psychophysiological benefits of exposure to greenspaces compared to urban built environments reported in earlier studies might be less (or at least not only) due to features of the greenspaces than to additional stressors, such as road traffic noise in the urban built environment. Hence, differences in the effects attributed to greenness in previous studies may also be due to potentially detrimental noise effects in comparison settings. This paper reports the study protocol for a randomized, controlled intervention study comparing the effects of walking in forest versus urban built environments, taking road traffic noise exposure during walks in the respective settings into account. METHODS: The protocol envisages a field study employing a pretest-posttest design to compare the effects of 30-min walks in urban built environments and forests with different road traffic noise levels. Assessments will consist of self-reported measures, physiological data (salivary cortisol and skin conductance), an attention test, and noise, as well as greenness measurements. The outcomes will be restoration, stress, positive and negative affect, attention, rumination, and nature connectedness. DISCUSSION: The results will inform about the restorative effect of walking in general, of exposure to different types of environments, and to different noise levels in these sites. The study will provide insights into the benefits of walking and nature-based interventions, taking into account the potential detrimental effects of noise exposure. It will thus facilitate a better understanding of low-threshold interventions to prevent stress and foster wellbeing. TRIAL REGISTRATION: ISRCTN48943261 ; Registered 23.11.2023.

Trait impulsivity influences behavioural and physiological responses to threat in a virtual environment.

Trait impulsivity represents a tendency to take action without forethought or consideration of consequences. This trait is multifaceted and can be decomposed into attentional, motor and non-planning subtypes of impulsivity. The purpose of the current study was to investigate how subtypes of trait impulsivity responded to different degrees of threat within room-scale virtual reality (VR) with respect to behaviour and level of physiological activation. Thirty-four participants were required to negotiate a virtual environment (VE) where they walked at height with the continuous threat of a virtual 'fall.' Behavioural measures related to the speed of movement, interaction frequency and risk were collected. Participants also wore ambulatory sensors to collect data from electrocardiogram (ECG) and electrodermal activity (EDA). Our results indicated that participants who scored highly on non-planning impulsivity exhibited riskier behaviour and higher skin conductance level (SCL). Participants with higher motor impulsivity interacted with more objects in the VE when threat was high, they also exhibited contradictory indicators of physiological activation. Attentional impulsivity was associated with a greater number of falls across the VE. The results demonstrate that subtypes of trait impulsivity respond to threats via different patterns of behaviour and levels of physiological activation, reinforcing the multifaceted nature of the trait.

Does vibrotactile stimulation of the auricular vagus nerve enhance working memory? A behavioral and physiological investigation.

BACKGROUND: Working memory is essential to a wide range of cognitive functions and activities. Transcutaneous auricular vagus nerve stimulation (taVNS) is a promising method to improve working memory performance. However, the feasibility and scalability of electrical stimulation are constrained by several limitations, such as auricular discomfort and inconsistent electrical contact. OBJECTIVE: We aimed to develop a novel and practical method, vibrotactile taVNS, to improve working memory. Further, we investigated its effects on arousal, measured by skin conductance and pupil diameter. METHOD: This study included 20 healthy participants. Behavioral response, skin conductance, and eye tracking data were concurrently recorded while the participants performed N-back tasks under three conditions: vibrotactile taVNS delivered to the cymba concha, earlobe (sham control), and no stimulation (baseline control). RESULTS: In 4-back tasks, which demand maximal working memory capacity, active vibrotactile taVNS significantly improved the performance metric d' compared to the baseline but not to the sham. Moreover, we found that the reduction rate of d' with increasing task difficulty was significantly smaller during vibrotactile taVNS sessions than in both baseline and sham conditions. Arousal, measured as skin conductance and pupil diameter, declined over the course of the tasks. Vibrotactile taVNS rescued this arousal decline, leading to arousal levels corresponding to optimal working memory levels. Moreover, pupil diameter and skin conductance level were higher during high-cognitive-load tasks when vibrotactile taVNS was delivered to the concha compared to baseline and sham. CONCLUSION: Our findings suggest that vibrotactile taVNS modulates the arousal pathway and could be a potential intervention for enhancing working memory.

Transcranial focused ultrasound of the amygdala modulates fear network activation and connectivity.

BACKGROUND: Current noninvasive brain stimulation methods are incapable of directly modulating subcortical brain regions critically involved in psychiatric disorders. Transcranial Focused Ultrasound (tFUS) is a newer form of noninvasive stimulation that could modulate the amygdala, a subcortical region implicated in fear. OBJECTIVE: We investigated the effects of active and sham tFUS of the amygdala on fear circuit activation, skin conductance responses (SCR), and self-reported anxiety during a fear-inducing task. We also investigated amygdala tFUS' effects on amygdala-fear circuit resting-state functional connectivity. METHODS: Thirty healthy individuals were randomized in this double-blinded study to active or sham tFUS of the left amygdala. We collected fMRI scans, SCR, and self-reported anxiety during a fear-inducing task (participants viewed red or green circles which indicated the risk of receiving an aversive stimulus), as well as resting-state scans, before and after tFUS. RESULTS: Compared to sham tFUS, active tFUS was associated with decreased (pre to post tFUS) blood-oxygen-level-dependent fMRI activation in the amygdala (F(1,25) = 4.86, p = 0.04, η2 = 0.16) during the fear task, and lower hippocampal (F(1,27) = 4.41, p = 0.05, η2 = 0.14), and dorsal anterior cingulate cortex (F(1,27) = 6.26, p = 0.02; η2 = 0.19) activation during the post tFUS fear task. The decrease in amygdala activation was correlated with decreased subjective anxiety (r = 0.62, p = 0.03). There was no group effect in SCR changes from pre to post tFUS (F(1,23) = 0.85, p = 0.37). The active tFUS group also showed decreased amygdala-insula (F(1,28) = 4.98, p = 0.03) and amygdala-hippocampal (F(1,28) = 7.14, p = 0.01) rsFC, and increased amygdala-ventromedial prefrontal cortex (F(1,28) = 3.52, p = 0.05) resting-state functional connectivity. CONCLUSIONS: tFUS can change functional connectivity and brain region activation associated with decreased anxiety. Future studies should investigate tFUS' therapeutic potential for individuals with clinical levels of anxiety.

Skin Conductance-Based Acupoint and Non-Acupoint Recognition Using Machine Learning.

Acupoints (APs) prove to have positive effects on disease diagnosis and treatment, while intelligent techniques for the automatic detection of APs are not yet mature, making them more dependent on manual positioning. In this paper, we realize the skin conductance-based APs and non-APs recognition with machine learning, which could assist in APs detection and localization in clinical practice. Firstly, we collect skin conductance of traditional Five-Shu Point and their corresponding non-APs with wearable sensors, establishing a dataset containing over 36000 samples of 12 different AP types. Then, electrical features are extracted from the time domain, frequency domain, and nonlinear perspective respectively, following which typical machine learning algorithms (SVM, RF, KNN, NB, and XGBoost) are demonstrated to recognize APs and non-APs. The results demonstrate XGBoost with the best precision of 66.38%. Moreover, we also quantify the impacts of the differences among AP types and individuals, and propose a pairwise feature generation method to weaken the impacts on recognition precision. By using generated pairwise features, the recognition precision could be improved by 7.17%. The research systematically realizes the automatic recognition of APs and non-APs, and is conducive to pushing forward the intelligent development of APs and Traditional Chinese Medicine theories.

Stress Inoculation in Police Officers Using Virtual Reality: A Controlled Study.

Policing is a highly demanding and stressful profession. Virtual reality (VR) has emerged as a promising tool for enhancing stress management programs, including for police officers. The use of VR in combination with biosensors enables measurement of psychophysiological responses such as peripheral temperature (PT) and skin conductance level (SCL). This study investigated the psychophysiological responses of police officers exposed to a VR scenario simulating a car accident. The study included a total of 63 police officers from the Public Security Police. Participants were divided into three groups based on their police divisions: the Investigation Brigade of Traffic Accidents, the Traffic Surveillance Squad (TSS), and a control group from the Lisbon Metropolitan Command. The results indicated that the VR environment effectively induced psychophysiological arousal, particularly in less experienced officers (TSS), that is, there were significant group differences in mean SCL and PT, showing this group with higher SCL and lower PT during the VR exposure. These results support the potential of VR as a stress inoculation strategy for training police officers and highlight the complex nature of stress responses that are influenced by individual factors and psychopathology.

Social Signal Processing in Affective Virtual Reality: Human-Shaped Agents Increase Electrodermal Activity in an Elicited Negative Environment.

Prior research on affect elicitation indicates that stimuli with social content (pictures or videos) are more arousing than nonsocial stimuli. In particular, they elicit stronger physiological arousal as measured by electrodermal activity (EDA; i.e., social EDA effect). However, it is unclear how this effect applies to virtual reality (VR), which enables an enhanced sense of presence (SoP) and ecological validity. The study here approached this question from a social-emotional VR framework. A sample of N = 72 participants (55 percent women) experienced a set of six virtual environments (VEs) in the form of emotional parks specifically designed to elicit positive, negative, or neutral affectivity. Half of these VEs included human-shaped agents (social context) and the other half omitted these agents (nonsocial context). The results supported the social EDA effect, which in addition was amplified by the reported SoP. Importantly, the VE featuring a social negative content qualified this observed social EDA effect. The finding is discussed in the light of a negativity bias reported in affect literature, through which negative stimuli typically mobilize attention and bodily activation as a mechanism linked to stress responses. The study's implications extend to the use of VR in both research and practical applications, emphasizing the role of social content in influencing affective and physiological responses.

Topographic mapping of the sensorimotor qualities of empathic reactivity: A psychophysiological study in people with spinal cord injuries.

The experience of empathy for pain is underpinned by sensorimotor and affective dimensions which, although interconnected, are at least in part behaviorally and neurally distinct. Spinal cord injuries (SCI) induce a massive, below-lesion level, sensorimotor body-brain disconnection. This condition may make it possible to test whether sensorimotor deprivation alters specific dimensions of empathic reactivity to observed pain. To explore this issue, we asked SCI people with paraplegia and healthy controls to observe videos of painful or neutral stimuli administered to a hand (intact) or a foot (deafferented). The stimuli were displayed by means of a virtual reality set-up and seen from a first person (1PP) or third person (3PP) visual perspective. A number of measures were recorded ranging from explicit behaviors like explicit verbal reports on the videos, to implicit measures of muscular activity (like EMG from the corrugator and zygomatic muscles that may represent a proxy of sensorimotor empathy) and of autonomic reactivity (like the electrodermal response and Respiratory Sinus Arrhythmia that may represent a general proxy of affective empathy). While no across group differences in explicit verbal reports about the pain stimuli were found, SCI people exhibited reduced facial muscle reactivity to the stimuli applied to the foot (but not the hand) seen from the 1PP. Tellingly, the corrugator activity correlated with SCI participants' neuropathic pain. There were no across group differences in autonomic reactivity suggesting that SCI lesions may affect sensorimotor dimensions connected to empathy for pain.

Validating the usefulness of Sudoscan in ATTRv: a single centre experience.

BACKGROUND: Variant transthyretin amyloidosis (ATTRv) can cause sensorimotor and autonomic neuropathy. Objective quantification of sudomotor function may be essential for early diagnosis and early initiation of treatment. The aim of this study is to evaluate the diagnostic value of the Sudoscan® in ATTRv. METHODS: Electrochemical skin conductance (ESC) was measured in V30M ATTRv patients, asymtomatic V30M carriers and healthy controls. Comparisons between the three groups were made using the Kruskal-Wallis test, and ROC curves were used to estimate the discriminatory power of ESC values between groups. RESULTS: ESC was measured in 52 ATTRv patients, 107 asymptomatic carriers and 40 healthy controls. ESC was significantly lower in ATTRv patients compared to asymptomatic carriers and healthy controls in both feet and hands; median values are as follows: 40 µS, 78 µS and 81 µS, respectively (p < 0.001), and 53 µS, 69 µS and 74 µS, respectively (p < 0.001). ESC in feet < 70.5 µS had a sensitivity of 89.7% and specificity of 84.6% to discriminate asymptomatic carriers from patients with ATTRv. CONCLUSION: The determination of ESC by Sudoscan® is a rapid, noninvasive and easily reproducible technique capable of discriminating patients with ATTRv from asymptomatic carriers and healthy controls with adequate sensitivity and specificity.

The effect of emotion regulation on the emotional modulation of pain and nociceptive flexion reflex.

ABSTRACT: Positive emotions inhibit pain, whereas negative emotions facilitate pain. Thus, many psychosocial interventions capitalize on this emotion-pain relationship to improve patients' abilities to regulate emotion (ie, reduce negative emotion, increase positive emotion), influence nociception, and manage pain. This study extended the existing literature to examine whether emotion regulation procedures could influence emotional modulation of the nociceptive flexion reflex (NFR), a marker of spinal nociception. To elicit emotion, 2 blocks of pleasant, neutral, and unpleasant pictures were presented. In block 1, participants were asked to passively view pictures during which painful electric stimulations were delivered to evoke pain and the NFR. Valence, arousal, corrugator electromyogram, and skin conductance response were used to measure emotional responses to pictures. To manipulate emotion regulation, participants were randomized to either suppress (downregulate) or enhance (upregulate) their emotion during block 2 (other procedures same as block 1). Instructions to suppress decreased subjective and physiological responding to emotional pictures, reduced emotional modulation of pain, and generally decreased NFR magnitude (regardless of picture content). Instructions to enhance emotion increased subjective responding to emotional pictures but did not alter physiological responding to pictures or emotional modulation of pain/NFR in predictable ways. Results imply that downregulation/suppression of negative emotions may work best to reduce pain facilitation. Furthermore, this study contributes to the existing literature that shows that pain and pain signaling is tightly coupled with emotional states and that emotion regulation can impact pain perception.

Psychophysiological correlates of pain resilience in anticipating, experiencing, and recovering from pain.

Although researchers have documented behavioral and brain structure correlates of pain resilience, associated physiological responses have received little consideration. In this study, we assessed psychophysiological differences between high (HPR), moderate (MPR), and low (LPR) pain resilience subgroups during anticipation, experiencing, and recovery from laboratory pain. In an initial pain anticipation task, participants (79 women, 32 man) viewed visual cues to signal possible mild or intense shocks prior to receiving these shocks. Subsequently, in a pain recovery task, participants received uncued mild and intense shocks. Subjective appraisals were assessed during each task in tandem with continuous recording of skin conductance level (SCL), heart rate variability (HRV), and corrugator electromyography (cEMG). On physiological indexes, HPR subgroup members displayed significantly lower SCL than MPR and LPR subgroups did during anticipation and experiencing of pain while no resilience group effects were found for HRV or cEMG. During pain recovery, HPR and LPR subgroups displayed weaker SCL than the MPR subgroup did in the immediate aftermath of shock. However, HPR members continued to display lower SCL than other groups did over an extended recovery period. On self-report measures, the LPR subgroup reported higher levels of anticipatory anxiety and expected pain than HPR and MPR subgroups did during the pain anticipation task. Together, results suggested higher pain resilience is characterized, in part, by comparatively reduced SCL during the course of anticipating, experiencing and recovering from painful shock.

Imaginal extinction and the vividness of mental imagery: Exploring the reduction of fear within the mind's eye.

Patients are encouraged to produce vivid mental imagery during imaginal exposure, as it is assumed to promote fear reduction. Nevertheless, the link between fear reduction and imagery vividness is unclear. We investigated the impact of vividness on fear responses using an experimental analogue of imaginal exposure - imaginal extinction - in which conditioned fear, measured with skin conductance, is reduced through exposure to mental imagery of the conditioned stimulus. We examined (1) if task-specific vividness (high vs low) of the conditioned stimulus during imaginal extinction moderated the reduction of fear responses, and (2) if task-specific vividness influenced remaining fear responses 24 h later. Findings suggest that high vividness may be advantageous for fear reduction during imaginal extinction, but it may not influence fear responses in the longer term. A possible clinical implication is that high imagery vividness during imaginal exposure may not be vital for overall treatment outcome. As high vividness is associated with increased levels of distress, a future direction would be to explore whether similar fear reduction can be obtained with less vivid imaginal exposure and thereby make treatment tolerable for more patients.

Impaired differential learning of fear versus safety signs in obsessive-compulsive disorder.

Pavlovian learning mechanisms are of great importance both for models of psychiatric disorders and treatment approaches, but understudied in obsessive-compulsive disorder (OCD). Using an established Pavlovian fear conditioning and reversal procedure, we studied skin conductance responses in 41 patients with OCD and in 32 matched healthy control participants. Within both groups, fear acquisition and reversal effects were evident. When comparing groups, patients showed impaired differential learning of threatening and safe stimuli, consistent with previous research. In contrast to prior findings, differential learning impairments were restricted to fear acquisition, and not observed in the reversal stage of the experiment. As previous and present fear reversal experiments in OCD differed in the use of color coding to facilitate stimulus discrimination, the studies converge to suggest that differential learning of threatening versus safe stimuli is impaired in OCD, but manifests itself differently depending on the difficulty of the association to be learned. When supported by the addition of color, patients with OCD previously appeared to acquire an association early but failed to reverse it according to changed contingencies. In absence of such color coding of stimuli, our data suggest that patients with OCD already show differential learning impairments during fear acquisition, which may relate to findings of altered coping with uncertainty previously observed in OCD. Impaired differential learning of threatening versus safe stimuli should be studied further in OCD, in order to determine whether impairments in differential learning predict treatment outcomes in patients, and whether they are etiologically relevant for OCD.

Exposure to intimate partner aggression during childhood is associated with blunted skin conductance recovery following stress in early adulthood.

This study examines skin conductance level (SCL) trajectories and childhood exposure to intimate partner aggression (IPA) committed between parents in a sample of college students. Although IPA among parents does not directly involve children, children frequently see or are exposed to IPA first-hand when it occurs. This exposure to IPA increases risks for psychopathology and emotional or behavioral difficulties for children or adolescents later in life. However, research has not yet examined the stress response patterns of individuals exposed to IPA, nor how reactivity to stress may be altered based on this exposure. Participants included 161 college students who completed questionnaires assessing demographics, mental health, and exposure to IPA, and also reported on family functioning and parental drinking habits. Additionally, participants completed a three-minute mirror tracing task followed by a three-minute recovery period while SCL was monitored. Multilevel modeling was used to assess whether frequency or level of exposure to IPA was related to trajectories of SCL. Neither variable was related to SCL trajectories during the mirror-tracing task. However, both frequency and level of exposure were related to SCL trajectories during the recovery period, such that for participants reporting higher levels of either IPA exposure variable, SCL trajectories during recovery declined less rapidly and did not decline to as low of a level compared to participants reporting lower levels of IPA exposure. This blunted SCL recovery may be due to wear and tear from repeated innervation, or a calibrating of the SCL response to adapt to a volatile home environment.

The absence of differential electrodermal responding in the second half of acquisition does not indicate the absence of fear learning.

Many contemporary studies of human fear conditioning exclude participants who fail to show differential electrodermal responding during late stages of acquisition training, deeming them to be non-Learners. The current study examined whether non-Learners, defined as those who fail to show larger electrodermal first interval responses to CS+ than to CS- in the second half of acquisition, show differential electrodermal responding early during acquisition or during extinction or evidence of fear-learning on other measures, including rated CS valence and contingency report. In a sample of 351 participants who completed a standard differential fear-conditioning paradigm that employed electrodermal first and second interval responses (FIR, SIR), continuous CS evaluations, and post-experimental contingency reports to assess fear-learning, 74 participants were identified as non-Learners. These non-Learners displayed overall smaller electrodermal responses but showed evidence for differential conditioning during acquisition in electrodermal FIR (block1) and SIR (blocks 2-3) and in CS evaluations during acquisition (blocks 2-4) and extinction (blocks 1-4). Fifty-nine non-Learners correctly reported the contingencies. A lack of differential electrodermal first interval responding during the second half of acquisition does not indicate the absence of fear-learning. Rather, this criterion appears to capture participants who exhibit low physiological arousal and performance decrements toward the end of acquisition. Applying criteria based on "end of acquisition" electrodermal responding to determine "non-learning" results in the exclusion of participants who display fear-learning at other experimental stages or in other measures.

The skin conductance response indicating pain relief is independent of self or social influence on pain.

Pain relief is defined as the ease of pain and is thus highly relevant for clinical applications and everyday life. Given that pain relief is based on the cessation of an aversive pain experience, it is reasonable to assume that pain relief learning would also be shaped by factors that alter subjective and physiological pain responses, such as social presence or a feeling of control. To date, it remains unclear whether and how factors that shape autonomic pain responses might affect pain relief learning. Here, we investigated how pain relief learning is shaped by two important factors known to modulate pain responses, i.e. social influence and controllability of pain. Skin conductance responses (SCRs) were recorded while participants learned to associate a formerly neutral stimulus with pain relief under three different pain conditions. In the social-influence condition (N = 34), the pain stimulation could be influenced by another person's decisions. In the self-influence condition (N = 31), the participants themselves could influence the pain stimulation. Finally, in the no-influence condition (N = 32), pain stimulation was simply delivered without any influence. According to our results, the SCRs elicited by the stimulus that was associated with pain relief were significantly smaller compared to the SCRs elicited by a neutral control stimulus, indicating pain relief learning. However, there was no significant difference in the pain relief learning effect across the groups. These results suggest that physiological pain relief learning in humans is not significantly influenced by social influence and pain controllability.

Rating expectations can slow aversive reversal learning.

The process of learning allows organisms to develop predictions about outcomes in the environment, and learning is sensitive to both simple associations and higher order knowledge. However, it is unknown whether consciously attending to expectations shapes the learning process itself. Here, we directly tested whether rating expectations shapes arousal during classical conditioning. Participants performed an aversive learning paradigm wherein one image (CS+) was paired with shock on 50% of trials, while a second image (CS-) was never paired with shock. Halfway through the task, contingencies reversed. One group of participants rated the probability of upcoming shock on each trial, while the other group made no online ratings. We measured skin conductance response (SCR) evoked in response to the CS and used traditional analyses as well as quantitative models of reinforcement learning to test whether rating expectations influenced arousal and aversive reversal learning. Participants who provided online expectancy ratings displayed slower learning based on a hybrid model of adaptive learning and reduced reversal of SCR relative to those who did not rate expectations. Mediation analysis revealed that the effect of associative learning on SCR could be fully explained through its effects on subjective expectancy within the group who provided ratings. This suggests that the act of rating expectations reduces the speed of learning, likely through changes in attention, and that expectations directly influence arousal. Our findings indicate that higher order expectancy judgments can alter associative learning.

Countering information leakage in the Concealed Information Test: The effects of item detailedness.

Concealed Information Tests (CIT) are administered to verify whether suspects recognize certain features from a crime. Whenever it is presumed that innocent suspects were contaminated with critical information (e.g., the perpetrator had a knife), the examiner may ask more detailed questions (e.g., specific types of knives) to prevent false positives. However, this may increase the number of false negatives if the true perpetrator fails to discern specific details from its plausible irrelevant controls, or because detailed crime-scene information may be forgotten. We examined whether presenting items at the exemplar level protects against contamination, and whether it compromises the sensitivity in a physiological CIT. Participants (N = 142) planned a mock-robbery, with critical items encoded either at the category or at the exemplar level. The CIT was administered immediately or after a 1-week-delay, with questions phrased at the categorical or exemplar level. There were no effects of time delay. Results revealed that when item detailedness was congruent at encoding and testing, the SCR, HR, and RLL showed larger differential responses, as compared with incongruent conditions. Participants contaminated with crime knowledge at the categorical level did not show a CIT-effect for crime details at the exemplar level, suggesting detailed questions may counter the leakage problem. Asking questions at the exemplar level did not reduce the CIT detection efficiency as compared to asking questions at the categorical level. The importance of congruency between encoding and testing provides examiners with a challenge, as it is difficult to estimate how details are naturally encoded.

Acute relaxation during pregnancy leads to a reduction in maternal electrodermal activity and self-reported stress levels.

BACKGROUND: Prenatal maternal stress can have adverse effects on birth outcomes and fetal development. Relaxation techniques have been examined as potential countermeasures. This study investigates different relaxation techniques and their effect on self-reported stress levels and physiological stress levels in pregnant women. METHODS: In this cross-sectional study, 38 pregnant women in their 30th to 40th gestational week were assigned to one of three, 20-min lasting relaxation groups: listening to music (N = 12), following a guided imagery (N = 12) or resting (N = 12). The intervention, i.e., acute relaxation (music, guided imagery or resting) took place once for each study participant. Study inclusion criteria were age over 18 years, German speaking, singleton and uncomplicated pregnancy during the 30th and 40th week of gestation. The stress levels were determined during the study. Current stress level during the study was assessed by a visual analogue scale. Chronic stress levels were assessed by the Trier Inventory of Chronic Stress and the Pregnancy Distress questionnaire. Multivariate analyses of covariance were performed and dependent measures included stress levels as well as physiological measures, i.e., cardiovascular activity (electrocardiogram) and skin conductance levels. RESULTS: All three forms of relaxation led to reduced maternal stress which manifested itself in significantly decreased skin conductance, F(3,94) = 18.011, p = .001, ηp2 = .365, and subjective stress levels after the interventions with no significant group difference. Post-intervention stress ratings were further affected by gestational age, with less subjective relaxation in women later in gestation, F (1, 34)=4.971, p = .032, ηp2 = .128. CONCLUSION: Independent of relaxation technique, single, 20-min relaxation intervention (music, guided imagery or resting) can significantly reduce maternal stress. Notably, women at an earlier stage in their pregnancy reported higher relaxation after the intervention than women later in gestation. Hence, gestational age may influence perceived stress levels and should be considered when evaluating relaxation or stress management interventions during pregnancy. TRIAL REGISTRATION: Not applicable.

Cardiac response in aversive and appetitive olfactory conditioning: Evidence for a valence-independent CS-elicited bradycardia.

While the examination of conditioned cardiac responses is well established in human fear conditioning research, comparable studies using less-aversive or rather appetitive unconditioned stimuli (UCS) are sparse and results are mixed. Therefore, the aim of this study was a systematic analysis of cardiac reactions in aversive and appetitive conditioning. Olfactory stimuli were used as unconditioned stimuli as they are suitable reinforcers in both an aversive and an appetitive conditioning offering the opportunity for a comparison between conditioned responses. In total, n = 86 participants took part in both an aversive and an appetitive differential conditioning task with a counterbalanced order across participants. Aversive or appetitive odors, respectively, served as UCS and neutral geometrical figures as CS. Subjective ratings, skin conductance response (SCRs), and evoked cardiac reactions were analyzed and compared between tasks. Conditioned responses in subjective ratings could be observed in both aversive conditioning and appetitive conditioning, while SCRs discriminated between CS+ and CS- in aversive conditioning only. Regarding conditioned cardiac responses, the deceleration for the CS+ was longer than for the CS- in both tasks. In addition, a higher deceleration magnitude and a shorter acceleration for the CS+ as compared to the CS- were found in aversive but not in appetitive conditioning. There were medium-size correlations between aversive and appetitive CRs for subjective ratings and none for physiological responses. The results suggest similarities between cardiac response patterns in aversive and appetitive conditioning, which implies that bradycardia in conditioning might not be fear-specific but presents a valence-independent CS-elicited bradycardia.