Infants' Vagal Regulation in the Still-Face Paradigm Is Related to Dyadic Coordination of Mother-Infant Interaction.

The authors investigated relations between mother-infant dyadic coordination and infants' physiological responses. Mothers (N=73) and 3-month-old male and female infants were observed in the still-face paradigm, and mothers' and infants' affective states were coded at 1-s intervals. Synchrony and levels of matching between mother-infant affective states were computed, and infants' heart rate and vagal tone were measured. Infants showed increased negative affect and heart rate and decreased vagal tone during mothers' still-face, indicating physiological regulation of distress. Infants who did not suppress vagal tone during the still-face (nonsuppressors) showed less positive affect, higher reactivity and vagal suppression in normal play and reunion episodes, and lower synchrony in normal play with mothers. The results indicate that infants' physiological regulation in social interaction differs in relation to dyadic coordination of affective behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Major depression and cardiac autonomic control

We investigated autonomic control of heart rate in patients with major depression, melancholic type. Twenty-three depressed inpatients who were being treated with tricyclic antidepressants and 23 depressed patients who were taking no medications were compared with age- and sex-matched control groups on resting cardiac vagal tone and heart rate. In unmedicated depressed patients, cardiac vagal tone was comparable to that of control subjects, but heart rate was significantly higher. This increase in heart rate may have been due to sympathetic activation caused by anxiety, since the depressed patients were significantly more anxious than the control subjects. Medicated patients exhibited diminished cardiac vagal tone and higher heart rate than unmedicated patients and controls. This was probably due to the anticholinergic effects of the antidepressants. Our findings suggest that cardiac vagal tone is not lower than normal in patients with depression, melancholic type.     

Infant temperament and cardiac vagal tone: assessments at twelve weeks of age

Sixty 12-week-old infants participated in a laboratory study to explore the relations between temperament and cardiac vagal tone. Temperament was evaluated via laboratory observations and maternal ratings. Cardiac vagal tone, measured as the amplitude of respiratory sinus arrhythmia, was quantified from beat-to-beat heart period data collected during a resting baseline period and during the laboratory assessment of temperament. Specific hypotheses were investigated relating temperament to both basal cardiac vagal tone and changes in cardiac vagal tone during social/attention challenges. Infants with higher baseline cardiac vagal tone were rated in the laboratory as showing fewer negative behaviors and were less disrupted by the experimental procedure. Infants who decreased cardiac vagal tone during the laboratory assessment were rated on maternal report temperament scales as having longer attention spans, and being more easily soothed.     

Autonomic origins of cardiac responses to nonsignal stimuli in the rat.

Heart rate (HR) and blood pressure responses to nonsignal auditory stimuli were measured in rats after saline or pharmacological blockade of the sympathetic or vagal innervation of the heart. HR responses to the low-intensity stimulus were predominantly deceleratory, whereas responses to the high-intensity stimulus were more notably acceleratory. Both stimuli elicited a biphasic pressor–depressor response, although potential baroreflex influences accounted for only a small proportion of the HR response variance. Deceleratory responses to the low-intensity stimulus were eliminated by scopolamine and thus appeared to be predominantly of vagal origin. Acceleratory response to the high-intensity stimulus appeared to be mediated primarily by sympathetic activation because it was substantially attenuated by the β? antagonist atenolol. Furthermore, HR responses to the low-intensity stimulus appeared to reflect coactivation of both sympathetic and vagal systems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Phenytoin as a countermeasure for motion sickness in NASA maritime operations

Seasickness is the most prevalent form of motion sickness and is an operational problem during Space Shuttle Solid-fueled Rocket Booster (SRB) retrieval. Phenytoin has been shown to protect against motion sickness induced by Coriolis stress. We exposed SRB recovery personnel to off-vertical rotation and sea motion after phenytoin or placebo. Phenytoin blood levels of at least 9 micrograms/ml were protective against motion sickness at sea. No change in susceptibility to nitrogen narcosis was seen in divers in chamber tests at 460 KPa. Phenytoin was used during performance of critical and hazardous tasks during training and actual SRB recovery operations. Phenytoin is an effective operational countermeasure for motion sickness for selected SRB crewmembers.     

Selective discrete Fourier transform algorithm for time-frequency analysis: method and application on simulated and cardiovascular signals

The Selective Discrete Fourier transform (DFT) Algorithm [SDA] method for the calculation and display of time-frequency distribution has been developed and validated. For each time and frequency, the algorithm selects the shortest required trace length and calculates the corresponding spectral component by means of DFT. This approach can be extended to any cardiovascular related signal and provides time-dependent power spectra which are intuitively easy to consider, due to their close relation to the classical spectral analysis approach. The optimal parameters of the SDA for cardiovascular-like signals were chosen. The SDA perform standard spectral analysis on stationary simulated signals as well as reliably detect abrupt changes in the frequency content of nonstationary signals. The SDA applied during a stimulated respiration experiment, accurately detected the changes in the frequency location and amplitude of the respiratory peak in the heart rate (HR) spectrum. It also detected and quantified the expected increase in vagal tone during vagal stimuli. Furthermore, the HR time-dependent power spectrum displayed the increase in sympathetic activity and the vagal withdrawal on standing. Such transient changes in HR control would have been smeared out by standard heart rate variability (HRV), which requires consideration of long trace lengths. The SDA provides a reliable tool for the evaluation and quantification of the control exerted by the Central Nervous System, during clinical and experimental procedures resulting in nonstationary signals.     

Axonal and dendritic transport in Purkinje cells of cerebellar slice cultures studied by microinjection of horseradish peroxidase

BACKGROUND: The pathophysiological mechanisms in non-ulcer dyspepsia are incompletely understood. AIMS: To compare gastric motor and sensory functions in Helicobacter pylori positive or negative patients with non-ulcer dyspepsia. PATIENTS: Seventeen patients with non-ulcer dyspepsia and 16 asymptomatic controls. METHODS: The following were evaluated: gastrointestinal symptoms; gastric emptying and orocaecal transit of solids; abdominal vagal function; gastric compliance; fasting and postprandial gastric tone and phasic contractions; symptoms during ingestion of cold water and during the distension of an intragastric bag; and somatic sensitivity and personality profile (Minnesota Multiphasic Personality Inventory, MMPI). RESULTS: Gastric accommodation was reduced in H pylori negative dyspeptics relative to controls; the degree of accommodation was unrelated to H pylori status in dyspeptics. Increased postprandial gastric sensation was more frequent among H pylori positive patients (4/5 H pylori positive versus 4/12 H pylori negative patients). Intragastric meal distribution and orocaecal transit were normal; gastric emptying at four hours was abnormal in 4/17 patients. Vagal dysfunction was rare. Eight of 17 patients had somatisation or depression on MMPI. CONCLUSION: Impaired gastric accommodation is frequent in non-ulcer dyspepsia and seems to be unrelated to vagal efferent dysfunction. H pylori infection does not seem to influence gastric accommodation, but is associated with heightened sensitivity in dyspeptics. Therapeutic approaches that restore normal postprandial accommodation and gastric sensitivity should be tested in non-ulcer dyspepsia.     

Reactivity and developmental competence in preterm and full-term infants.

Evaluated physiological and behavioral reactivity to a novel stimulus in 24 preterm and 24 full-term infants at 8 mo and examined its association with developmental competence. Infants who reacted to the stimulus with increased vagal tone more often engaged in focused examination and exhibited greater range in exploratory play than those whose vagal tone decreased in response to the stimulus. Some differences in developmental performance were detected based on term status. Preterm perinatal risk factors were inversely associated with exploratory examination and range. Results are discussed in terms of a challenge model for assessing behavioral and physiological functioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Estrogen improves performance of reinforced T-maze alternation and prevents the amnestic effects of scopolamine administered systemically or intrahippocampally

In a previous study, administration of high doses of estradiol benzoate (100 microgram/kg for 3 days im) to ovariectomized Long-Evans rats counteracted impairments of reinforced T-maze alternation induced by systemic administration of scopolamine, a muscarinic receptor blocker. In the current study, daily administration of lower doses of estradiol benzoate (5 microgram/kg for 3 weeks sc) increased the number of correct reinforced alternations during T-maze acquisition in ovariectomized rats compared to oil-treated controls and prevented impairments of reinforced alternation induced by injection of scopolamine hydrobromide (0.2 mg/kg ip). Furthermore, scopolamine (20 microgram) delivered bilaterally to the dorsal hippocampus reduced reinforced T-maze alternation in ovariectomized rats previously trained to complete this task while daily treatment with estradiol benzoate (5 microgram/kg sc) for 1 week prior to scopolamine infusion counteracted this impairment. In summary, physiological levels of estrogen improved performance during acquisition of reinforced T-maze alternation and prevented impairments induced by scopolamine administered systemically or intrahippocampally.     

"Meta-analysis: statistical alchemy for the 21st century": discussion. A plea for a more balanced view of meta-analysis and systematic overviews of the effect of health care interventions

Ventricular arrhythmias and disturbed autonomic control, as reflected by abnormal heart rate variability (HRV), are related to hemodynamic impairment in chronic heart failure (CHF). We investigated the effects of orally (p.o.) administered isomazole, a new phosphodiesterase (PDE) inhibitor with calcium-sensitizing properties, on hemodynamics, ventricular arrhythmias, and HRV and examined a possible interaction between these parameters. Hemodynamic measurements and ambulatory ECG monitoring were performed in 12 patients with stable CHF class III-IV after single doses of isomazole 5-30 mg. Pulmonary wedge pressure decreased after 5, 10, 20, and 30 mg, but cardiac output, (CO) increased only after the higher doses [20 mg, + 20% (p = 0.031)] of isomazole. HR did not change. Mean arterial and pulmonary artery pressure, (MAP, PAP) decreased significantly in the 10- and 20-mg groups [10 mg, -6% (p = 0.035) and -14% (p < 0.001) respectively; 20 mg, -13% (p = 0.047) and -31% (p = 0.006), respectively]. Isomazole did not exert a significant effect on ventricular arrhythmias in the subsequent 24 h after acute dosing. Analysis of HRV showed that rMSSD and pNN50 (parameters of vagal tone) tended to increase after isomazole administration. Normalized high-frequency power during the day increased from 17.4 to 22.3 nu (p < 0.05), whereas low frequency tended to decrease from 52.7 to 48.2 nu (p = 0.06). Acute isomazole administration improves hemodynamics but has no effect on ventricular arrhythmias. The HRV variability data suggest development of an increase in vagal control of HR, parallel to the acute hemodynamic improvement after isomazole. Withdrawal of vagal control of HR in CHF may be a reversible process.     

Influence of Rocking Motion on Vibratory Roller-Based Measurement of Soil Stiffness

Experimental data have shown that vibratory roller compactors often exhibit rotational kinematics in addition to translation during operation. This rotation is not considered in roller-integrated measurement systems that estimate soil stiffness based on drum vibration. To model and explore the effect of rotation, a lumped parameter roller/soil model was developed. The machine parameters for this model were tuned from suspended drum testing that isolated the drum from the ground. The model was then verified using field data collected over a range of excitation frequencies on spatially homogenous soil, and over transversely heterogeneous soil using one excitation frequency. Rotational motion was found to significantly influence roller-integrated measurement of soil stiffness based on single position drum vibration data. Rotational motion causes single position measurement system results to be nonunique and to vary depending on the direction of roller travel. Using the model, various alternative measurement schemes were investigated. The directional dependence was eliminated by deriving a measurement at the drum’s center of gravity, and dual-sided measurement is proposed to gain a measure of heterogeneity. A more theoretical approach was also created wherein the contact force between the drum and soil are measured rather then being calculated.     

Line Broadening in the Fundamental Band of CO in CO-He and CO-Ar Mixtures

The effect of H. pylori infection on gastric motility and sensation is unclear. Our hypothesis is that H. pylori infection increases gastric sensation and reduces gastric accommodation and emptying. In eight H. pylori-positive and eight H. pylori-negative asymptomatic subjects, infection was proven by antral histology or culture. We evaluated: (1) gastric emptying of solids, (2) proximal gastric compliance, (3) fasting and postprandial proximal gastric tone and phasic contractions, (4) gastric sensation during balloon inflations or ingestion of cold water, and (5) abdominal vagal function. H. pylori infection was associated with lower gastric accommodation (median 75% postprandial increase in barostat balloon volume compared to fasting) when compared to the accommodation in uninfected volunteers (median 211% change from fasting). One H. pylori-positive subject had an abnormal abdominal vagal function test and her gastric accommodation response was reduced. Other motor and sensory functions in the two groups were similar. In asymptomatic volunteers, H. pylori infection and gastritis result in reduced accommodation (diastolic dysfunction) but no change in overall sensation or motor functions of the stomach.     

Control of a virtual vehicle influences postural activity and motion sickness.

Everyday experience suggests that drivers are less susceptible to motion sickness than passengers. In the context of inertial motion (i.e., physical displacement), this effect has been confirmed in laboratory research using whole body motion devices. We asked whether a similar effect would occur in the context of simulated vehicles in a visual virtual environment. We used a yoked control design in which one member of each pair of participants played a driving video game (i.e., drove a virtual automobile). A recording of that performance was viewed (in a separate session) by the other member of the pair. Thus, the two members of each pair were exposed to identical visual motion stimuli, but the risk of behavioral contagion was minimized. Participants who drove the virtual vehicle (drivers) were less likely to report motion sickness than participants who viewed game recordings (passengers). Data on head and torso movement revealed that drivers tended to move more than passengers, and that the movements of drivers were more predictable than the movements of passengers. Before the onset of subjective symptoms of motion sickness movement differed between participants who (later) reported motion sickness and those who did not, consistent with a prediction of the postural instability theory of motion sickness. The results confirm that control is an important factor in the etiology of motion sickness and extend this finding to the control of noninertial virtual vehicles. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Child and mother cardiac vagal tone: Continuity, stability, and concordance across the first 5 years.

In this prospective longitudinal study, vagal tone and heart period were measured at 2 months and at 5 years in children and their mothers to evaluate the development of vagal regulation at rest and during an environmental task. Child baseline vagal tone and heart period were discontinuous; mother baseline vagal tone was discontinuous, but heart period was continuous. Group mean baseline-to-task change in vagal tone and heart period were continuous in both children and mothers. Children reached adult levels of baseline vagal tone by 5 years and did not differ from their mothers in baseline-to-task change in vagal tone or heart period. Baseline vagal tone tended to be stable, but baseline heart period and baseline-to-task change in vagal tone and heart period were unstable in children; both were stable in mothers. Baseline-to-task change in vagal tone showed consistent child–mother concordance. These findings contribute to understanding psychophysiological development. especially the ontogenesis of the vagal system and its regulatory capacity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Edrophonium provocative testing during electrogastrography (EGG): effects on dyspeptic symptoms and the EGG

The aim of this study was to determine whether edrophonium induces dyspeptic symptoms and/or gastric myoelectric changes in normal subjects and patients with functional dyspepsia. Eighteen normal controls and 28 patients with functional dyspepsia underwent electrogastrography (EGG) with edrophonium administration. After EGG recording with 1-hr fasting and 2-hr postprandial periods, subjects received an intravenous infusion of saline (placebo) followed by edrophonium 10 mg. After each injection, the EGG was recorded for 15 min and symptoms scored. Patients with functional dyspepsia had significantly more frequent gastrointestinal symptoms in response to edrophonium than normal controls. Edrophonium had no effect on EGG dominant frequency, but increased the power of the dominant frequency in both controls and dyspeptic patients. In the dyspeptic patients, reproduction of the patient's symptoms was associated with an increase in the power of the dominant frequency, whereas when no symptoms were produced, there was no change in power. Overall, 21 of 28 dyspeptic patients (75%) had either an abnormal baseline EGG (N=10) or a normal EGG and positive edrophonium test (N=11). In conclusion, edrophonium administration can reproduce symptoms in some dyspeptic patients. Symptoms after edrophonium administration may be related to either more vigorous gastric contractions and/or increased visceral perception of normal gastric contractions.     

Effects of anxiety arousal and mental stress on the vestibulo-ocular reflex

Although the subjective reports of patients suggest that anxiety may aggravate vertigo and imbalance, there has been little research into how anxiety might directly affect balance system functioning. We conducted two studies to examine the effect of anxiety and arousal on the vestibulo-ocular reflex (VOR). In the first study, pre-lest fear ratings were obtained from 20 normal subjects and 36 anxious subjects immediately prior to rotation and caloric testing. Fear ratings were significantly correlated with the maximum slow-phase velocity (SPV) of nystagmus induced by caloric testing. In the second study, we assessed the VOR response to rotation of 36 normal subjects under 3 task conditions: a) minimal alerting (counting backwards during rotation), b) physical arousal (induced by exertion prior to rotation); c) mental arousal (induced by performance of stressful mental tasks during rotation). Both the physical and mental tasks induced a significant increase in heart rate compared with the alerting condition. The maximum SPV of the nystagmus induced by rotation was significantly greater during performance of the mental task than in the other two conditions. These combined results indicate that anxiety may influence the gain of the VOR.     

Increased heart rate in depressed subjects in spite of unchanged autonomic balance?

A clinical study was conducted to examine the effects of depression on cardiac autonomic control. Cardiac autonomic control was measured in 26 nonmedicated patients (19 females) suffering from Major Depression, melancholic type, and in 26 age- and sex-matched normal controls. We measured heart rate and high frequency heart rate variability (respiratory sinus arrhythmia), pulsewave velocity and blood pressure, during 10 min of supine rest under controlled conditions. Using a log transformed time domain measure of respiratory sinus arrhythmia (logRSA), we found an inverse linear dependence between cardiac vagal tone and age in the healthy subjects as well as the depressed patients. logRSA was 0.22+/-0.25 in the patients and 0.25+/-0.16 in the control group. While this difference was not significant (P > 0.1), the deviations from the regression line were significantly (P < 0.0005) greater in the patients (0.21+/-0.12) than in the control group (0.09+/-0.07), indicating a more heterogeneous vagal tone in the depressed patients. Heart rate was also significantly (P < 0.03) greater in the depressed patients (76.6+/-12.4) than in the control group (69.5+/-6.9). No between-group differences were found in pulsewave velocity or systolic blood pressure, but diastolic blood pressure was lower in depressed patients (73.5+/-8.7 vs. 80.8+/-9.1). We discuss the possibility that the increased heart rate seen in the absence of vagal tone changes may not be due to altered vagal or sympathetic tone, as measured in this study. Other factors, including altered autonomous heart rate, may be responsible for the higher heart rate in the depressed group.     

Effects of worry on physiological and subjective reactivity to emotional stimuli in generalized anxiety disorder and nonanxious control participants.

The present study examined the effect of worry versus relaxation and neutral thought activity on both physiological and subjective responding to positive and negative emotional stimuli. Thirty-eight participants with generalized anxiety disorder (GAD) and 35 nonanxious control participants were randomly assigned to engage in worry, relaxation, or neutral inductions prior to sequential exposure to each of four emotion-inducing film clips. The clips were designed to elicit fear, sadness, happiness, and calm emotions. Self reported negative and positive affect was assessed following each induction and exposure, and vagal activity was measured throughout. Results indicate that worry (vs. relaxation) led to reduced vagal tone for the GAD group, as well as higher negative affect levels for both groups. Additionally, prior worry resulted in less physiological and subjective responding to the fearful film clip, and reduced negative affect in response to the sad clip. This suggests that worry may facilitate avoidance of processing negative emotions by way of preventing a negative emotional contrast. Implications for the role of worry in emotion avoidance are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Anxiety and autonomic flexibility: a cardiovascular approach

Autonomic characteristics of panickers, blood phobics, and nonanxious controls were compared with a variety of cardiovascular measures, including spectral analysis of the cardiac inter-beat interval time series (derived from the electrocardiogram). Responses to laboratory stressors (shock avoidance and cold face stress) of 16 participants who reported recent occurrences of frequent severe panic attacks, 15 participants who reported strong somatic reactions and fainting to the sight of blood, and 15 controls, were recorded. Results suggested distinct autonomic patterns among the three groups. Across conditions, panickers displayed the highest heart rates (HR) coupled with the least HR variability, which indicates low levels of cardiac vagal tone. Blood phobics showed more vagally mediated HR variability than panickers, with a significant association between cardiac rate and mean arterial pressure. Controls generally showed the most HR variability and 'spectral reserve' (a quality that indicates flexible responsivity). Results are discussed in the context of traditional models of anxiety and autonomic activity in contrast to contemporary notions of stability and change in biological systems.     

Parental drinking problems and children's adjustment: Vagal regulation and emotional reactivity as pathways and moderators of risk.

Children's emotional regulation (as indexed by vagal suppression) and children's emotional reactivity during an argument were examined as moderators and mediators of parental problem drinking and children's adjustment in a sample of 6- to 12-year-olds. Cardiac vagal tone was assessed during both a baseline condition and exposure to an audiotaped argument. Vagal suppression was calculated by subtracting vagal tone during the baseline from that recorded during the argument, with a higher number representing increased suppression of vagal tone during the argument. Emotional reactivity was based on both observations of overt behaviors of children and their reported feelings during the argument. A higher level of vagal suppression was a protective factor against children's externalizing, internalizing, and social problems associated with exposure to parental problem drinking. Emotional reactivity was a vulnerability factor, and children's increased anger and fear, and to a lesser degree sadness, each moderated and exacerbated the effects of parental problem drinking on child outcomes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)