Cardiac awareness and autonomic cardiac reactivity during emotional picture viewing and mental stress

This study investigated the relationship between autonomic cardiovascular reactivity and cardiac awareness during the following conditions: baseline, emotional picture viewing, mental stress, and heartbeat tracking. Cardiac parameters were examined by using power spectrum analysis of heart rate variability and impedance cardiography. According to their performance in a heartbeat tracking task, 38 participants were classified as good (n=19) or poor (n=19) heartbeat perceivers. Neither group differed during baseline and heartbeat tracking, but good compared to poor heartbeat perceivers demonstrated greater sympathetic reactivity during mental stress and more vagal reactivity and subjective arousal during emotional picture viewing. The results suggest that cardiac awareness is related to greater responsivity of the autonomic nervous system during situations evoking autonomic reactivity.     

Goal relevance and goal conduciveness appraisals lead to differential autonomic reactivity in emotional responding to performance feedback

Using an appraisal framework, the present experiment tested the hypothesis that goal relevance and goal conduciveness have an interactive effect on emotional responding. We expected that elicitation of positive or negative emotions in response to events that are conducive or obstructive to attainment of one's goals depends on the level of goal relevance. To test this hypothesis, we presented 119 participants with positive (success) or negative (failure) performance feedback of high or low relevance in an achievement context. Feeling self-report showed effects of conduciveness, but no interaction with relevance. Physiological reactivity showed the predicted interaction effect on cardiac autonomic regulation (CAR), with higher CAR for high-relevance conducive than obstructive conditions. Moreover, mean arterial pressure (MAP) and skin conductance level (SCL) differed between conducive and obstructive conditions, and heart rate (HR) and SCL differed between relevance conditions. Implications for the plausibility and current empirical support of the interaction hypothesis are discussed.     

Diurnal variations in central venous pressure

We analysed the haemodynamic patterns of seven monkeys (Macaca mulatta) during a one-month period during which we monitored beat-to-beat levels of heart rate, stroke volume, intra-arterial pressure and central venous pressure 7 days/week, 18 h/day. We replicated an earlier finding that cardiac output falls and total peripheral resistance rises throughout the night: the fall in cardiac output was mediated by a fall in heart rate since stroke volume did not change; and the rise in peripheral resistance reflected a homeostatic adjustment to the fall in cardiac output since blood pressure was stable throughout the night although it fell early in the evening. In addition, we have shown for the first time that central venous pressure also falls throughout the night; this occurs even in the presence of alpha- and beta-adrenergic sympathetic blockade. Since stroke volume does not change overnight this indicates that the nocturnal fall in cardiac output is not due to a shift of blood volume into the venous compartment. These findings support our hypothesis that there is a nocturnal decline in plasma volume.     

Diurnal variations in mitotic activity in mice

Summary A study was made of the regularities in the 20-hour changes in the mitotic activity of intestinal epithelium of the salivary glands, pancreas, kidney, epidermis and corneal epithelium of mice. Changes of the functional activity of these organs were recorded simultaneously. Regular 24-hour changes of mitotic activity were noted in various test organs. The 24-hour mitotic rhythm curves had two peaks in the case of digestive organs: in case of the kidney the curves were also double-peaked, the peaks, however, being less marked. The second peak of the cellular mitotic activity curve is connected with the regimen of the animal feeding. The curves of the 24-hour rhythm of the number of mitoses had a single peak in the case of corenal epithelium and epidermis. In the 24-hour changes of the cellular mitotic activity there existed a reverse relationship between the number of dividing cells and the functional activity of the organ.(Presented by Active Member AMN SSSR V. V. Parin) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 53, No. 4, pp. 100–104, April, 1962     

Diurnal variations of tonic electrodermal activity.

Diurnal variability of skin conductance level (SCL) was examined in two complementary experiments, simultaneously with variability of skin temperature (ST) and that of simple reaction time (RT) which was recorded as a behavioural index of arousal. In Experiment I, 6 subjects spent 6 days in the laboratory in homogeneous conditions. Three recording sessions, each lasting 2 h, began, respectively, at 9:00 a.m. (morning), 1:00 p.m. (afternoon) and 5:00 p.m. (evening). Results indicated that SCL increased linearly throughout the day. Experiment II was undertaken to test whether this effect could still be observed in more heterogeneous conditions. Subjects (n = 12) attended to their own activities between the two 30-min sessions beginning, respectively, at 9:30 a.m. and 6:00 p.m. during a single experimental day. Again, SCL was higher in the evening than in the morning. In both experiments the SCL pattern seemed to be asynchronous with ST and RT variations. Taken as a whole, these data bring additional evidence of temporal electrodermal variation, a phenomenon which should be further taken into account in EDA research.     

Diurnal variations in subcutaneous allergen immunotherapy reactions

Background

Circadian rhythms underlie many immune responses and allergic diseases. Subcutaneous immunotherapy (SCIT) can result in adverse reactions; however, it is unclear whether such reactions have a diurnal pattern.

Diurnal variations in serum biochemical and haematological measurements.

Twenty five biochemical and haematological measurements were determined on nonfasting blood and serum samples collected between 9 am and 7 pm from a representative group of 7685 British middle-aged men. Most measurements showed significant diurnal variations, but only for bilirubin, phosphate, and triglyceride did time of day account for more than 5% of the between subject variance. Serum bilirubin concentrations showed a pronounced downward trend in the afternoon, the mean value after 6 pm being 30% lower than the mean value in the morning. Mean serum triglyceride and phosphate concentrations increased steadily through the day. Mean concentrations of potassium, haemoglobin, and haematocrit and red cell count were higher in the morning, while urea and creatinine concentrations and white cell count had higher means in the afternoon. Glucose showed a pattern consistent with short term response to meals. The effects of these diurnal trends on routine use of biochemical tests needs careful consideration, and a greater understanding of their biological mechanisms is required.     

Diurnal variations in coagulation and fibrinolysis in vital exhaustion

OBJECTIVE: Vital exhaustion (VE) predicts a first myocardial infarction (MI) and new cardiac events after a coronary angioplasty. To explore potential underlying pathophysiological mechanisms, we tested whether VE is associated with more pronounced diurnal variations in hemostasis. METHODS: Blood was drawn from 29 VE and 30 control males, all healthy and nonsmokers, to assess hemostatic measures at 7:00 AM and 6:00 PM. RESULTS: All measures of fibrinolysis were in their normal range and showed significant diurnal variations. These variations were more pronounced in VE as all fibrinolytic measures were significantly higher in VE at 7:00 AM and similar to those of controls at 6:00 PM, thus supporting our hypothesis with respect to fibrinolysis. Diurnal decreases in tPA and tPA-PAI ranged from 1.5 (VE) to 1.3 (controls), whereas the diurnal decrease in PAI-1 was more than fourfold in VE and 2.7-fold in controls. This suggests a decreased fibrinolytic capacity in VE during the early morning. All coagulation measures were in their normal range, and prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complexes, and activated factor VII showed significant diurnal variations. These variations were similar in VE and control individuals, thus not supporting our hypothesis with respect to coagulation. Finally, F1+2 and fibrinogen were both significantly higher throughout the day in VE. CONCLUSIONS: VE is associated with decreased early morning fibrinolysis and increased fibrinogen levels throughout the day. These hemostatic changes may promote thrombus formation and provide a potential pathophysiological mechanism by which VE is related to MI and its circadian variation.     

Gastric myoelectrical and autonomic cardiac reactivity to laboratory stressors

We evaluated the effects of two laboratory stressors (speech preparation and isometric handgrip) on gastric myoelectrical and autonomic cardiac activity, and the extent to which autonomic responses to these stressors and somatization predict reports of motion sickness during exposure to a rotating optokinetic drum. Both stressors prompted a decrease in preejection period (PEP) and respiratory sinus arrhythmia (RSA), and an increase in a dysrhythmic pattern of gastric myoelectrical activity, termed gastric tachyarrhythmia. Stressor-induced decreases in RSA and higher somatization scores predicted increased reports of motion sickness during drum rotation. These results demonstrate that laboratory stressors concurrently affect gastric myoelectrical activity and autonomic control of the heart, and that stressor-induced decreases in RSA and higher levels of somatization predict motion sickness susceptibility.     

Deficits in early emotional reactivity in alexithymia

Alexithymia is characterized by a difficulty in identifying and describing one's emotions. This study addressed the question of whether alexithymic tendencies are related to limited affective reactivity to briefly presented emotional stimuli. Skin conductance responses were assessed and backward masking was used to minimize elaborated processing of emotional pictures. Results indicated that alexithymic tendencies are associated with smaller electrodermal responses to briefly presented negative pictures. These effects were driven by difficulties in identifying and communicating emotions whereas externally orientated thinking was unrelated to affective reactivity. We conclude that there is an early processing deficit in response to negative stimuli in participants with high scores in alexithymia. Differences in the early emotional reactivity to arousing material could contribute to difficulties in emotional processes related to alexithymia.     

Diurnal variations of serum erythropoietin in trained and untrained subjects

The diurnal variations of serum-erythropoietin concentration ([s-EPO]) were investigated in six physically trained (T) and eight untrained (UT) men. The T subjects had a higher mean maximal oxygen uptake than UT subjects [75.7 (SEM 1.6) ml · min^–1 · kg^–1 versus 48.3 (SEM 1.4) ml · min^–1 · kg^–1, P < 0.0001] and a lower mean body mass index [BMI, 21.7 (SEM 0.7) kg · m^–2 versus 24.4 (SEM 0.6) kg · m^–2, P=0.02]. Each subject was followed individually for 24 h as they performed their normal daily activities. Venous blood samples were collected from awakening (0 min) until the end of the 24-h period (1440 min). Both T and UT had a nadir of [s-EPO] 120 min after awakening [10.0 (SEM 0.3) U · 1^–1 versus 11.5 (SEM 2.1) U · 1^–1, P > 0.05]. The UT and T increased their [s-EPO] to peak values at 960 min and 960–1200 min, respectively (ANOVA P=0.03) after awakening [UT: 18.4 (SEM 2.8) U · l^–1; T: 16.2 (SEM 2.5) U · l^–1, P > 0.05]. The mean 24-h [s-EPO] were 14.5 (SEM 1.0) U · l^–1 and 14.9 (SEM 0.9) U · l^–1 in T and UT, respectively (P > 0.05). The individual mean 24-h [s-EPO] were not correlated to body mass, BMI or maximal oxygen uptaken. Significant diurnal variations in [s-EPO] occurred in these healthy subjects irrespective of their levels of physical activity.     

Disturbed sleep and emotional reactivity in 5-year-old children

Background

Individual differences in emotional reactivity may be associated with sleep disturbances. This study aimed at assessing the possible association between emotional reactivity and sleep disturbance in preschool children.

Methods

The study was conducted in 2011 and comprised 142 apparently healthy preschool children (78 boys, 64 girls) from the community setting selected by chance. The children did not have any inborn abnormalities, disabilities, or chronic and progressive diseases; they were 5 years old at the time of study, were singletons born in St. Petersburg, and attended preschool day care centers. Children completed the Sleep Self Report (SSR) questionnaire. The items from the SSR were considered separately, and groups of questions were added to produce the scores in three dimensions of sleep problems: difficulty going to bed, sleep duration and night waking, and daytime sleepiness. The Achenbach Caregiver-Teacher Report Form for Ages 1.5–5 for the caregivers was used to calculate the emotional reactivity.

Results

The higher levels of emotional reactivity were more commonly associated with the children’s self-reported habits of falling asleep in their parents’ or sibling’s bed, nightmares seen, and feeling sleepy during the day. The more emotionally reactive children felt rested less commonly after night sleep. A statistically significant positive correlation was found between the level of emotional reactivity and the calculated values of the night waking, daytime sleepiness, and global sleep disturbances scores. These associations remained significant after adjustment for major potential confounders.

Conclusion

A high level of emotional reactivity is associated with sleep disturbances in preschool children.     

Diurnal variations of serum erythropoietin at sea level and altitude

This study tested the hypothesis that the diurnal variations of serum-erythropoietin concentration (serum-EPO) observed in normoxia also exist in hypoxia. The study also attempted to investigate the regulation of EPO production during sustained hypoxia. Nine subjects were investigated at sea level and during 4 days at an altitude of 4350 m. Median sea level serum-EPO concentration was 6 (range 6–13) U·l^–1. Serum-EPO concentration increased after 18 and 42 h at altitude, [58 (range 39–240) and 54 (range 36–340) U·l^–1, respectively], and then decreased after 64 and 88 h at altitude [34 (range 18–290) and 31 (range 17–104) U·l^–1, respectively]. These changes of serum-EPO concentration were correlated to the changes in arterial blood oxygen saturation (r = –0.60,P = 0.0009), pH (r = 0.67,P = 0.003), and in-vivo venous blood oxygen half saturation tension (r = –0.68,P = 0.004) but not to the changes in 2, 3 diphosphoglycerate. After 64 h at altitude, six of the nine subjects had down-regulated their serum-EPO concentrations so that median values were three times above those at sea level. These six subjects had significant diurnal variations of serum-EPO concentration at sea level; the nadir occurred between 0800–1600 hours [6 (range 4–13) U·l^–1], and peak concentrations occurred at 0400 hours [9 (range 8–14) U·l^–1,P = 0.02]. After 64 h at altitude, the subjects had significant diurnal variations of serum-EPO concentration; the nadir occurred at 1600 hours [20 (range 16–26) U·l^–1], and peak concentrations occurred at 0400 hours [31 (range 20–38) U·l^–1,P = 0.02]. This study demonstrated diurnal variations of serum-EPO concentration in normoxia and hypoxia, with comparable time courses of median values. The results also suggested that EPO production at altitude is influenced by changes in pH and haemoglobin oxygen affinity.     

Diurnal variations in suicide by age and gender in Italy

BACKGROUND: Recent Italian statistics on suicide distribution by time of day also report data on gender and age of victims, factors which have been shown to influence the seasonal distribution of suicide and which could also affect the influence of biological circadian rhythms on suicidal behaviour. This study aims to identify and evaluate any diurnal variations that may be present in suicide occurrence by age and gender in Italy, considering data from 1994 to 1997. METHODS: The null hypothesis that there are no variations in the distribution of suicides by time of day (or over the three major periods of the day: morning, afternoon, evening/night) was tested with the chi2 goodness-of-fit test and with ANOVA. RESULTS: A clear diurnal variation in the distribution of suicides over time can be observed for both genders, with a peak in the late morning (08:00-11:00 h), and a subsequent decrease to a trough in the night hours. This trend varies with age for both genders: in particular, the age groups 45-64 and 65+ show a clear suicide peak in the morning (08:00-11:00 h), whereas younger people have a peak number of suicides in the late afternoon (16:00-19:00 h). Adults (25-44 years old) show an intermediate trend, with a less pronounced peak between the morning and early afternoon hours. The observed trend is more marked among males; however, the distribution of suicides by time of day is clearly congruent by age between both genders. CONCLUSIONS: Diurnal variation in suicide occurrence by age group may be affected by factors distributed unevenly across age groups. In particular, age distribution of disorders leading to suicidal ideation, and the sensitivity of biological systems of different age groups to environmental cues may affect each group's risk of suicide. Socio-relational factors are also likely to contribute to diurnal variation in suicide risk by age and gender. Children and adolescents can generally be presumed to be at school during the morning, therefore their opportunity for self-harm is restricted to afternoon hours. The elderly, on the other hand, may find themselves alone in the morning, when family and friends spend more time away from home due to daily work activities. LIMITATIONS: Data are based on time of death and not on presumed time of the suicidal act. For suicides committed by certain methods (e.g., poisoning) there may be a considerable difference between time of act and time of death. CLINICAL RELEVANCE: The existence of a temporal window in suicide risk implies an improvement in the surveillance of people at risk of suicide and greater attention to chronobiological factors affecting those suffering from mental disorders leading to suicide ideation.     

Dissociations between psychobiologic reactivity and emotional expression in children

Although there are general assumptions that physiological and behavioral indices of emotion are interrelated, empirical research has revealed inconsistent findings with regard to their degree of association, particularly in children. Two studies were conducted to examine the relations between cardiovascular reactivity and emotional behavior. In the first study, 3- to 6-year-olds completed challenging tasks during which measures of their physiological responses and facial expressions were obtained. With age, children's heart rate decreased, vagal tone increased, and facial expressions became slightly more exaggerated. However, children's physiologic reactions were unrelated to their concurrent facial expression when all children were considered, when only boys were considered, and when children extreme in their physiologic reactions were considered. Only among girls was physiologic reactivity moderately associated with concurrent negative expressiveness. In the second study, 4- and 5-year-olds' physiologic reactivity was examined as a predictor of later overt emotional reaction to venipuncture episodes. Children's overt emotional reactions were consistent across repeated venipunctures, and girls were more visibly distressed than boys. As in the first study, physiologic reactivity was generally unrelated to children's behavioral responses. Findings have implications for assumptions about the degree of coupling between biological and behavioral emotional systems in childhood.     

Developmental and contextual influences on autonomic reactivity in young children

Studies of cardiovascular reactivity in young children have generally employed integrated, physiologically complex measures, such as heart rate and blood pressure, which are subject to the multiple influences of factors such as blood volume, hematologic status, thermoregulation, and autonomic nervous system (ANS) tone. Reactivity studies in children have rarely employed more differentiated, proximal measures of autonomic function capable of discerning the independent effects of sympathetic and parasympathetic responses. We describe 1) the development, validity, and reliability of a psychobiology protocol assessing autonomic reactivity to challenge in 3- to 8-year-old children; 2) the influences of age, gender, and study context on autonomic measures; and 3) the distributions of reactivity measures in a normative sample of children and the prevalences of discrete autonomic profiles. Preejection period (PEP) and respiratory sinus arrythmia (RSA) were measured as indices of sympathetic and parasympathetic nervous system reactivity, respectively, and autonomic profiles were created to offer summative indices of PEP and RSA response. Results confirmed the protocol's validity and reliability, and showed differences in autonomic reactivity by age and study context, but not by gender. The studies' findings offer guidelines for future research on autonomic reactivity in middle childhood and support the feasibility of examining sympathetic and parasympathetic responses to challenge in 3- to 8-year-old children.     

Studying the dynamics of autonomic activity during emotional experience

Recent theories emphasize the dynamic aspects of emotions. However, the physiological measures and the methodological approaches that can capture the dynamics of emotions are underdeveloped. In the current study, we investigated whether moment‐to‐moment changes in autonomic nervous system (ANS) activity are reliably associated with the unfolding of emotional experience. We obtained cardiovascular and electrodermal signals from participants while they viewed emotional movies. We found that the ANS signals were temporally aligned across individuals, indicating a reliable stimulus‐driven response. The degree of response reliability was associated with the emotional time line of the movie. Finally, individual differences in ANS response reliability were strongly correlated with the subjective emotional responses. The current research offers a methodological approach for studying physiological responses during dynamic emotional situations.     

The pupil as a measure of emotional arousal and autonomic activation

Pupil diameter was monitored during picture viewing to assess effects of hedonic valence and emotional arousal on pupillary responses. Autonomic activity (heart rate and skin conductance) was concurrently measured to determine whether pupillary changes are mediated by parasympathetic or sympathetic activation. Following an initial light reflex, pupillary changes were larger when viewing emotionally arousing pictures, regardless of whether these were pleasant or unpleasant. Pupillary changes during picture viewing covaried with skin conductance change, supporting the interpretation that sympathetic nervous system activity modulates these changes in the context of affective picture viewing. Taken together, the data provide strong support for the hypothesis that the pupil's response during affective picture viewing reflects emotional arousal associated with increased sympathetic activity.