Heart Rate Reactivity and Type A Behavior as Modifiers of Physiological Response to Active and Passive Coping

We examined the long term predictivity of heart rate reactivity (HRR) and its relation to cardiovascular and biochemical activity during rest and during tasks requiring active and passive coping. HRR was determined in 28 young men by measuring peak heart rate change to cold pressor one year after performing tasks eliciting active and passive coping. Heart rate change to cold pressor was significantly correlated with change to active coping (r= .65, p<.01) and to passive coping (r= .53, p<.01). Responses to the tasks were equivalent for Type A and B subjects. On the other hand, high HRRs were significantly more reactive than low HRRs with the effect being most apparent during active coping. HRR appeared to be a trait stable over one year which predicted enhanced cardiac, neuroendocrine, and neuromuscular response.     

Nursing behavior in rats is impaired in a small nestbox and with hyperthermic pups

The supine nursing posture, which occurs increasingly as growing pups initiate nursing from their recumbent dam, was demonstrated to require more space than that provided in earlier studies of mother-young contact (e.g., Leon, Croskerry, & Smith, 1978). Further, hyperthermic rat pups were shown to be deficient in eliciting normal nursing behavior. During a 4-hr separation from their dam, 7-day-old rat pups were incubated at 34°C (nest temperature) or at 39°C (WARM). Compared to controls, WARM-litter dams showed increased licking of and hovering over pups and decreased upright crouching, while WARM litters showed decreased nipple attachment and weight gain. On Day 13, similar effects occurred after incubation at 39°C (vs. 34°C), but not at 36 or 38°C. The results stress the need for ethologically meaningful conditions and direct behavioral observations to reveal the importance of pup activity in the mother-young dyad. © 1996 John Wiley & Sons, Inc.     

Diurnal and nocturnal nursing behavior in the OLETF rat

The Otsuka Long Evans Tokushima Fatty (OLETF) rat model of obesity has been recently found to develop hyperphagia and obesity early in life. Our goal was to investigate the dams' nursing behavior during the day and the night in order to elucidate their contribution to the pre‐obesity of the pups. We examined nursing bout number, length, posture, initiative, nursing total time and frequency of other maternal behaviors over the three postpartum (PP) weeks. In the first week, OLETF dams nursed more during the day and presented more self‐directed activities during the night. In the third PP week, OLETF dams displayed increased nursing time, bout number, nursing frequency, and supine postures at the beginning of the nursing episodes and less active self‐directed behaviors, both day and night, while OLETF pups displayed more initiative in starting nursing bouts. The results suggest a circadian difference in nursing behavior and self‐directed activities between the strains on PP week 1 and a strong influence of the OLETF pups on the nursing behavior of the dam on PP week 3, which contributes to their obese features. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 203–203, 2008.     

Modulation of Slow Cortical Potentials by Instrumentally Learned Blood Pressure Responses

We assessed whether instrumentally-learned pressor responses inhibit electrocortical acitivity, as predicted by learning theories of idiopathic hypertension. Subjects received beat-by-beat feedback for increases and decreases in mean arterial pressure measured from the finger (Peñáz method). Slow potentials were recorded from the midsagittal line during the final training session. Also recorded at this time were heart rate, eye movements, respiration, and post-session verbal reports of the subject's control strategies. Thirteen of 14 subjects differentiated blood pressure increases and decreases at p<.05 or better during the final session (within-subject discriminative operant procedure). Slow potentials were less negative on blood pressure increase compared to decrease trials at all midsagittal sites (p<.02), indicating relative cortical inhibition by pressor responses. This effect occurred even though subjects reported tensing of muscles on increase trials (p<.01), a behavioral activity previously associated with augmented rather than diminished cortical negativity. On increase trials slow potentials shifted toward positivity just prior to heart rate deceleration (the latter effect confirming activation of the baroreceptors).     

Is thoracolumbar fascia shear-wave modulus affected by active and passive knee flexion?

The purpose of this study was to examine the effect of passive and active knee flexion efforts on the stiffness of the thoracolumbar (TLF), semitendinosus (STF), and semimembranosus fascia (SMF). Fourteen young healthy males participated in this study. Using ultrasound shear-wave elastography, fascia elastic modulus was measured at rest (passive condition) and during submaximal isometric knee flexion efforts (active condition) with the hip at neutral position and the knee flexed at 0°, 45°, and 90°. Analysis of variance designs indicated that when the knee was passively extended from 90° to 0°, shear modulus of the TLF, SMF, and STF increased significantly (p < 0.05). Similarly, active knee flexion contractions caused a significant increase in TLF, SMF, and STF shear modulus (p < 0.001). Compared to hamstring fascia, the TLF showed greater thickness but a lower shear modulus (p < 0.05) while STF modulus was greater compared that to SMF during active contraction (p < 0.05). These results indicate that exercising the hamstring muscles can remotely influence the stiffness of the fascia which surrounds the lumbar area.     

Cardiovascular responses to autonomic stimuli in workers with vibration-induced white finger

Summary Cardiovascular responses to autonomic stimulation were assessed in 11 grinding operators affected with vibration-induced white finger (VWF) and in 11 comparable healthy controls by measuring blood pressures, heart rate and systolic time intervals (STI) during a hand-grip test, an arithmetic test and an orthostatic test. Digital circulatory function was also investigated by measurement of finger systolic pressure (FSP) during local cooling with water at 30°C, 15°C and 10°C. The increase in diastolic blood pressure and heart rate during the stress tests was greater in the VWF workers than in the controls. The STI values such as total electromechanical systole and left ventricular ejection time, were found to be shorter in the VWF subjects than in the controls at rest and during both the circulatory stress tests and the recovery periods (0.001<p<0.05). Multiple regression analysis showed that vibration exposure was the major predictor of STI during the stress tests, while age, smoking and drinking habits did not contribute substantially to the explained variation in STI. The reduction in FSP by local cooling from 30°C to 15°C and 10°C was greater in VWF operators than in controls (p<0.001), and total closure of the digital arteries at 10°C was observed in 8 VWF workers (72.7%). In all subjects significant relationships were found between the reduction in FSP at 10°C and the decrease in STI during circulatory stress activities (p<0.001). The findings in this study suggest an association between vibration exposure, digital vasospasm and increased cardiac sympathetic tone, the latter being demonstrated by the shortening of STI during the stress tests. It is suggested that excessive sympathetic reflex activity plays the dominant role in the pathogenesis of VWF.     

Modeling the cardiac indices of stress and performance of nuclear power plant operators during simulated fault scenarios

Acute stress can affect cognitive processing and decrease performance in demanding, stressful situations. Here, we recorded the cardiac indices of stress, that is, the heart rate and heart rate variability together with the physical activity of nuclear power plant operators, and examined their association with crew performance, while the operator crews were managing simulated incident and accident situations. Crew performance was evaluated both by the operator instructor and as the time taken to resolve the situation. In total, 64% of the variance in the information-seeking performance (adj-R² = .64, p < .01), and 41% of variation in the performance time (adj-R² = .41, p < .01) were explained by the psychophysiology. The cardiac measures indicated that increased stress was associated with poorer information-seeking performance and longer performance time. Increased physical activity was associated with poorer information seeking only. Otherwise, crew performance was robust, as the diagnosis and corrective actions, use of emergency operations procedures, and collaboration, were only weakly associated with the stress physiology. The association between information-seeking performance and stress might be explained by the larger requirement for cognitive processing at the information-gathering phase of the task. The results of the study show that psychophysiological measurements of stress and activity can provide valuable information on stress and its association with cognitive performance at work.     

Potential benefits of mindfulness during pregnancy on maternal autonomic nervous system function and infant development

Mindfulness is known to decrease psychological distress. Possible benefits in pregnancy have rarely been explored. Our aim was to examine the prospective association of mindfulness with autonomic nervous system function during pregnancy and with later infant social‐emotional development. Pregnant women (N = 156) completed self‐report mindfulness and emotional distress questionnaires, and had their autonomic function assessed in their first and third trimesters, including heart rate (HR), indices of heart rate variability (HRV), preejection period (PEP), and systolic (SBP) and diastolic blood pressure (DBP). The social‐emotional development of 109 infants was assessed at 4 months of age. More mindful pregnant women had less prenatal and postnatal emotional distress (p < .001) and higher cardiac parasympathetic activity: root mean square of successive differences (RMSSD: p = .03) and high‐frequency (HF) HRV (p = .02). Between the first and third trimesters, women's overall HR increased (p < .001), and HRV (RMSSD, HF HRV, and low‐frequency (LF) HRV: p < .001) and PEP decreased (p < .001). In more mindful mothers, parasympathetic activity decreased less (RMSSD: p = .01; HF HRV: p = .03) and sympathetic activity (inversely related to PEP) increased less (PEP: p = .02) between trimesters. Their offspring displayed less negative social‐emotional behavior (p = .03) compared to offspring of less mindful mothers. Mindfulness in pregnancy was associated with ANS changes likely to be adaptive and with better social‐emotional offspring development. Interventions to increase mindfulness during pregnancy might improve maternal and offspring health, but randomized trials are needed to demonstrate this.     

Diurnal and nocturnal nursing behavior in the OLETF rat

The Otsuka Long Evans Tokushima Fatty (OLETF) rat model of obesity has been recently found to develop hyperphagia and obesity early in life. Our goal was to investigate the dams' nursing behavior during the day and the night in order to elucidate their contribution to the pre-obesity of the pups. We examined nursing bout number, length, posture, initiative, nursing total time and frequency of other maternal behaviors over the three postpartum (PP) weeks. In the first week, OLETF dams nursed more during the day and presented more self-directed activities during the night. In the third PP week, OLETF dams displayed increased nursing time, bout number, nursing frequency, and supine postures at the beginning of the nursing episodes and less active self-directed behaviors, both day and night, while OLETF pups displayed more initiative in starting nursing bouts. The results suggest a circadian difference in nursing behavior and self-directed activities between the strains on PP week 1 and a strong influence of the OLETF pups on the nursing behavior of the dam on PP week 3, which contributes to their obese features.     

Vestibular influence on the cardiorespiratory responses to whole-body oscillation after standing

We assessed the influence of vestibular stimulation by whole-body oscillation in the yaw plane on the cardiorespiratory responses after a change of posture from sitting to standing. Eighteen healthy subjects (21–70 years old) and six patients with bilateral vestibular loss (46–59 years old) were tested. For comparison, a subgroup, age matched to the patients, was created from the healthy group. After a 10-min rest, subjects who were sitting, back unsupported, stood on a platform affording en bloc head and body support. The platform was either static or oscillated at 0.1 Hz and 0.5 Hz (20° amplitude) for 2 min. Presentation of the three conditions was counterbalanced. Respiration, ECG, blood pressure and head position were recorded. During oscillation at 0.5 Hz, the respiratory responses were different between groups; healthy subjects showed a significant increase of the respiratory frequency (1.75±2.1 breaths/min), which was not observed in the patients (0.16±0.7 breaths/min) (p<0.05, ANOVA). Absolute changes of heart rate and blood pressure were similar for the three conditions in all the subjects. However, healthy subjects showed a decrease of power spectrum density of the high-frequency ('respiratory') component of heart rate variability on standing during all three conditions. This response was variable among the patients and the age-matched group. The study shows that semicircular canal activation influences the respiratory rhythm during movements in the yaw plane in standing subjects. In addition, we observed that changes of the respiratory influence on heart rate variability during orthostatic stress are not affected by yaw oscillation or chronic vestibular loss, but may be affected by factors related to age. Electronic Publication     

Effect of mother's voice on neonatal respiratory activity and EEG delta amplitude

While the influence of the mother's voice on neonatal heart‐rate response and its relevant activity on cerebral cortex and the autonomic nervous system (ANS) are well known, few studies have assessed its influence on respiratory activity. We investigated the relationship among the respiration rate, the delta wave amplitudes through electroencephalography, and the basal state of ANS through the respiratory variability index while 22 full‐term neonates hear their mother's voice and an unknown voice. It was found that when respiratory variability was large, a transient (<5 s) change in respiration rates was observed in response to an unknown voice, while a greater increase in the delta wave amplitude was observed in the frontal lobe than the parietal one in response to the mother's voice. Conversely, when respiratory variability was small, a sustained increase (>10 s) in respiration rates was observed in response to the mother's voice, while a greater increase in the delta wave amplitude was found in both the frontal and parietal lobes. These results suggest that the basal state of ANS influences the latency of increases in respiration rates. Furthermore, induced by the mother's voice, transient increases in respiration rates are reduced in association with frontal lobe activity, and sustained increases in respiration rates are promoted in association with frontal and parietal lobe activities.     

Arousal episodes during sleep in the neonatal rat

Hippocampal EEG and neck EMG activity were recorded in restrained as well as in unrestrained rat pups following treatment with drugs which selectively suppress wakefulness and active sleep, respectively. Chloral hydrate did not affect active sleep but eliminated the bursts of coordinated total-body movements which were seen during sleep, especially under conditions of restraint. Chlorimipramine, in contrast, suppressed active sleep while sparing the coordinated total-body motility. It is concluded that these latter movements represent an episodic arousal phenomenon, against a background of quiet sleep, which becomes intensified under certain postural conditions.     

Daily physical activity in low-risk pre-term infants: Positive impact on bone strength and mid-upper arm circumference

Background: Prevention of pre-term osteopenia is important because it results in ventilator dependency, fractures in long bones, softening of the ribs or respiratory failure due to bone breaks in newborns.

Aim: The aim of this study was to evaluate the changes in bone strength and anthropometric indices of very low birth-weight (VLBW) pre-term infants undergoing daily physical activity.

Subjects and methods: Forty VLBW and low-risk pre-term infants (n intervention group = 20, n control group = 20) with a birth weight of 800–1600 g and gestational age of 26–32 weeks were recruited. Pre-term infants in the control group were provided with standard nursing care whereas those in the intervention group received a daily physical activity programme in addition to standard nursing care during the study. Before and after the study, anthropometric indices and tibial speed of sound (SOS) values were measured.

Results: In this study the tibial SOS values were found to be increased in the intervention group (p < 0.001) and decreased in the control group (p = 0.002). The increase in percentage of the mid-upper arm circumference of infants was significantly higher in the intervention group than in the control group (p < 0.001).

Conclusion: A daily physical activity programme increased SOS values of the tibia and mid-upper arm circumference in VLBW pre-term infants.     

Influence of respiratory rate on the variability of blood volume pulse characteristics

Photoplethysmogram (PPG) measures have been proven useful for the quantification of sympathetic reactivity and continuous monitoring of vascular reactivity. This study was designed to delineate the influence of respiratory rate on the variability of various PPG characteristics in time and frequency domains. PPG, electrocardiogram (ECG) and respiration were simultaneously recorded for 2 min from eight healthy volunteers during paced respiration of 6, 12 and 18 cycles min^?1. The PPG characteristics such as peak-to-peak interval (PPI), systolic peak amplitude, slope, T_crest, T_decay and pulse transit time (PTT) were computed for every pulse. In time domain, the mean of amplitude, slope and T_crest were not significantly different amongst three different respiratory rates. However, the mean of T_decay, PPI and PTT were significantly increased (p < 0.05, p < 0.05 and p < 0.01, respectively) during respiration of 6 cycles min^?1 compared to 12 cycles min^?1. The maximal spectral powers of the variability of all PPG measures were centred on the respiratory frequency in frequency domain. In conclusion, the results that the amplitude and slope in time domain are not altered by the respiratory frequency suggest their application in faithful assessment of cardiovascular reactivity. As the variability of PPI, T_decay and PTT are altered by the slow respiration, the influence of respiration on these time derivatives should not be ignored during interpretation of vascular reactivity.     

A method for continuously assessing the autonomic response to music-induced emotions through HRV analysis

Interest in therapeutic applications of music has recently increased, as well as the effort to understand the relationship between music features and physiological patterns. In this study, we present a methodology for characterizing music-induced effects on the dynamics of the heart rate modulation. It consists of three steps: (i) the smoothed pseudo Wigner-Ville distribution is performed to obtain a time–frequency representation of HRV; (ii) a parametric decomposition is used to robustly estimate the time-course of spectral parameters; and (iii) statistical population analysis is used to continuously assess whether different acoustic stimuli provoke different dynamic responses. Seventy-five healthy subjects were repetitively exposed to pleasant music, sequences of Shepard tones with the same tempo as the pleasant music and unpleasant sounds overlaid with the same sequences of Shepard tones. Results show that the modification of HRV parameters are characterized by an early fast transient phase (15–20 s), followed by an almost stationary period. All kinds of stimuli provoked significant changes compared to the resting condition, while during listening to pleasant music the heart and respiratory rates were higher (for more than 80% of the duration of the stimuli, p < 10⁻⁵) and the power of the HF modulation was lower (for more than 70% of the duration of the stimuli, p < 0.05) than during listening to unpleasant stimuli.     

Development of nasal respiration and sniffing in the rat

Nasal inhalation cycles of 1- to 20-day-old rat pups were measured and recorded using strain gage plethysmography, a technique that compares favorably with more common cinemagraphic methods of quantification. Respiratory recordings were taken from individual pups before and after habituation to a novel but bland environment, and in response to repeated, counterbalanced presentations of the odor of amyl acetate and gentle tactile stimulation. Baseline respiratory rates increased during the first two postnatal weeks and subsided in the third week. Rat pups of all ages displayed significant respiratory acceleration (polypnea) to suprathreshold olfactory and tactile stimulation, although there were ontogenetic differences in response topography. The occurrence and duration of bursts of polypnea increased with age. Sniffing, rhythmically regular episodes of polypnea, appeared as early as Day 3, but did not become prominent until about Day 11. The relationship between the development of nasal respiration and sniffing, and the development of olfaction in the rat was discussed.     

HEART RATE AND SOMATIC CHANGES DURING AVERSIVE CONDITIONING AND A SIMPLE REACTION TIME TASK

Four experiments are reported, all of which are concerned with evaluating in human Ss the relationship between the deceleration of heart rate, observed to anticipate both aversive and non-aversive stimuli, and several aspects of somatic-motor activity. In a simple reaction time task, a decrease in spontaneous bursts of EMG activity and both respiration amplitude and frequency were found to be concomitant with the deceleration of heart rate during the foreperiod and to be directly correlated with reaction time. The decrease in anticipatory somatic activity to an aversive stimulus was found in a second experiment to extend to spontaneous eye movements and blinks, which also had a marked concomitance with the anticipatory deceleration of heart rate. However, experimentally imposed somatic activity, i.e. continuous finger tapping, increased in intensity around the time the UCS was expected. A third experiment provided additional evidence that the anticipatory cardiac deceleration to aversive stimuli was not mediated significantly by respiratory maneuvers. Finally, evidence was provided that the basis for the spontaneous EMG bursts may be related to somatic responses elsewhere in the body, such as postural adjustments.     

Swallowing-related activities of respiratory and non-respiratory neurons in the nucleus of solitary tract in the rat

Swallowing-related activity was examined in respiratory (   n = 60  ) and non-respiratory (   n = 82  ) neurons that were located in and around the nucleus of the solitary tract (NTS) in decerebrated, neuromuscularly blocked and artificially ventilated rats. Neurons that were orthodromically activated by electrical stimulation of the superior laryngeal nerve (SLN) were identified, and fictive swallowing was evoked by SLN stimulation. The pharyngeal phase of swallowing was monitored by hypoglossal nerve activity. Two types of non-respiratory neurons with swallowing-related bursts were identified: 'early' swallowing neurons (   n = 24  ) fired during periods of hypoglossal bursts, and 'late' swallowing neurons (   n = 8  ) fired after the end of hypoglossal bursts. The remaining non-respiratory neurons were either suppressed (   n = 21  ) or showed no change in activity (   n = 29  ) during swallowing. On the other hand, respiratory neurons with SLN inputs included 56 inspiratory and four expiratory neurons. Inspiratory neurons were classified into two major types: a group of neurons discharged simultaneously with hypoglossal bursts (type 1 neurons,   n = 19  ), while others were silent during bursts but were active during inter-hypoglossal bursts when swallowing was provoked repetitively (type 2 neurons,   n = 34  ). Three of the expiratory neurons fired during hypoglossal bursts. Many of the swallowing-related non-respiratory neurons and the majority of the inspiratory neurons received presumed monosynaptic inputs from the SLN. Details of the distribution and firing patterns of these NTS neurons, which have been revealed for the first time in a fictive swallowing preparation in the rat, suggest their participation in the initiation, pattern formation and mutual inhibition between swallowing and respiration.     

Maladaptive behaviors in individuals with Angelman syndrome

Maladaptive behaviors are challenging and a source of stress for caregivers of individuals with Angelman Syndrome (AS). There is limited information on how these maladaptive behaviors vary over time among individuals with AS due to different genetic etiologies. In this study, caregivers of 301 individuals with AS were asked questions about their child's behavior and completed the Aberrant Behavior Checklist‐Community version (ABC‐C). Developmental functioning was evaluated with either the Bayley Scales of Infant Development, Third Edition (Bayley‐III) or the Mullen Scales of Early Learning (MSEL). Family functioning was assessed using the parent‐completed Parenting Stress Index (PSI) and the Family Quality of Life questionnaire (FQoL). Approximately 70% of participants had AS due to a deletion on the maternally‐inherited copy of chromosome 15q11q13. Results revealed that at baseline, individuals with AS had low scores in the domains of lethargy (mean: 2.6–4.2 depending on genotype) and stereotypy (mean: 2.3–4.2 depending on genotype). Higher cognitive functioning was associated with increased irritability (r = 0.32, p < .01). Hyperactivity (p < .05) and irritability (p < .05) increased with age across all genotypes and should be ongoing targets for both behavioral and pharmacological treatment. Concerns for short attention span were endorsed by more than 70% of caregivers at baseline. Maladaptive behaviors, particularly hyperactivity, irritability and aggression, adversely affected parental stress, and family quality of life.     

Ageing effects on knee and ankle joint angles at key events and phases of the gait cycle

The objective of this research was to determine whether joint angles at critical gait events and during major energy generation/absorption phases of the gait cycle would reliably discriminate age-related degeneration during unobstructed walking. The gaits of 24 healthy adults (12 young and 12 elderly) were analysed using the PEAK Motus motion analysis system. The elderly participants showed significantly greater single (60.3% versus 62.3%, p < 0.01) and double ( p < 0.05) support times, reduced knee flexion (47.7° versus 43.0°, p < 0.05) and ankle plantarflexion (16.8° compared to 3.3°, p = 0.053) at toe off, reduced knee flexion during push-off and reduced ankle dorsiflexion (16.8° compared to 22.0°, p < 0.05) during the swing phase. The plantarflexing ankle joint motion during the stance to swing phase transition (A₂) for the young group (31.3°) was about twice ( p < 0.05) that of the elderly (16.9°). Reduced knee extension range of motion suggests that the elderly favoured a flexed-knee gait to assist in weight acceptance. Reduced dorsiflexion by the elderly in the swing phase implies greater risk of toe contact with obstacles. Overall, the results suggest that joint angle measures at critical events/phases in the gait cycle provide a useful indication of age-related degeneration in the control of lower limb trajectories during unobstructed walking.