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Biomedical subjects

J F Thayer

Publications and source records attributed to J F Thayer.

At least 19 recordsLinked to original sources
PubMed2001

Heart rate and heart rate variability changes in the intracarotid sodium amobarbital test.

PURPOSE: Changes in heart rate and heart rate variability have been found in prior studies performed during the intracarotid sodium amobarbital (ISA) test. However, these results are not entirely consistent with current models of differential cerebral involvement in the modulation of the heart. This study was designed to re-investigate this topic with a larger N than has heretofore been used. METHODS: The electrocardiogram was recorded during left and right ISAs in 73 subjects. Raw heart rate and heart rate variability were calculated. RESULTS: Raw heart rate increased during inactivation of either hemisphere, but more so for the right hemisphere. Heart rate variability changes consistent with decreasing parasympathetic tone also were found to occur during either ISA, but to a significant degree, only during right ISA. CONCLUSIONS: The right hemisphere appears to have a greater role in cerebral regulation of cardiac function, perhaps by virtue of the modification of parasympathetic effects.

Adolescent↗
PubMed2001

A dynamical systems interpretation of a dimensional model of emotion.

The dimensional structure of emotion was investigated using self reports of induced mood and idiographic and nomothetic analyses. Subjects attended four experimental sessions during which an array of affective states was induced via auditory, visual, and imaginal channels. For each of 118 stimulus events, subjects self-rated their response. Factor analysis yielded the predicted bipolar factors of valence and arousal: these were obtained in group-aggregated analysis and subsequently confirmed as change dimensions at the intraindividual level. Controversy over the fundamental dimensions of affective space was considered with respect to methodological issues such as factor rotation and sampling of data space. Valence and arousal are discussed as motivational, driving parameters of affective experience and a dynamical systems conceptualization of emotion is proposed.

Arousal↗
PubMed2001

Derivation of chronotropic indices of autonomic nervous system activity using impedance cardiography.

The impedance cardiograph has been widely used to examine cardiac sympathetic inotropic activity. Recently evidence was presented indicating that left ventricular ejection time (LVET) may be a useful index of sympathetic chronotropic influences derivable from the impedance cardiograph. The goal of the present research was to derive an index of parasympathetic chronotropic influences. In addition, further support for LVET as a sympathetic chronotropic index was sought. Eight healthy college-age subjects participated in a within-subjects design experiment. Tasks were chosen to elicit a wide range of cardiovascular responses resulting from differing combinations of sympathetic and parasympathetic activity. Results indicated that heart rate corrected for LVET (HR-LVET) correlated highly with respiratory sinus arrhythmia (RSA), an index of vagal cardiac chronotropic activity. In addition, principal components analysis indicated that heart rate, RSA, LVET, HR-LVET, and HR corrected for RSA (HR-RSA) all loaded on a single factor distinct from inotropic or vascular indices. These results provide support for the use of impedance cardiography to derive indices of sympathetic (LVET) and parasympathetic (HR-LVET) chronotropic influences.

Adult↗
PubMed2001

The quest for the EEG reference revisited: a glance from brain asymmetry research.

Recent findings suggested that the choice of the EEG reference might be a critical issue for the study of anterior asymmetry in the alpha band. The present paper investigates the validity of different reference schemes for the measurement of alpha asymmetry. A 32-channel resting EEG was recorded with a common vertex reference (Cz), and transformed into computer-averaged ears (A1 + A2), average reference (AR), and current source density derivations. A correlation analysis of an alpha asymmetry measure between all derivation schemes indicated a poor convergent validity for anterior sites but an excellent convergent validity for posterior sites. Further analyses suggested the presence of substantial alpha activity at the various reference sites (Cz, A1 + A2, AR), which might be similar in magnitude to anterior but smaller than posterior alpha. These findings suggest that the validity of a reference scheme is a function of the signal-to-noise ratio of the electrical activities at target and reference sites. The limitations of each reference scheme for the measurement of anterior alpha asymmetry are discussed.

Adult↗
PubMed2000

Accentuated antagonism in the control of human heart rate.

Invasive animal models indicate that the accelerative effects of the sympathetic nervous system on heart rate are highly dependent on the background level of vagal activity. A noninvasive, parasympathetic chronotropic index (respiratory sinus arrhythmia) and a sympathetic chronotropic index (left ventricular ejection time) were used to evaluate autonomic control of human heart rate. A strong interaction, previously called accentuated antagonism, was found. Sympathetic heart rate effects were substantially smaller with high levels of vagal tone than with low vagal background activity. Furthermore, vagal effects became progressively stronger with increasing sympathetic background activity, demonstrating the predominance of parasympathetic control of human heart rate. This finding implies that changes in cardiac activity resulting from changes in sympathetic control cannot be interpreted accurately unless concurrent vagal activity is taken into account, as well.

Adult↗
PubMed2000

A model of neurovisceral integration in emotion regulation and dysregulation.

In the present paper we present the outlines of a model that integrates autonomic, attentional, and affective systems into a functional and structural network that may help to guide us in our understanding of emotion regulation and dysregulation. We will emphasize the relationship between attentional regulation and affective processes and propose a group of underlying physiological systems that serve to integrate these functions in the service of self-regulation and adaptability of the organism. We will attempt to place this network in the context of dynamical systems models which involve feedback and feedforward circuits with special attention to negative feedback mechanisms, inhibitory processes, and their role in response selection. From a systems perspective, inhibitory processes can be viewed as negative feedback circuits that allow for the interruption of ongoing behavior and the re-deployment of resources to other tasks. When these negative feedback mechanisms are compromised, positive feedback loops may develop as a result (of dis-inhibition). From this perspective, the relative sympathetic activation seen in anxiety disorders may represent dis-inhibition due to faulty inhibitory mechanisms.

Animals↗
PubMed2000

Sex differences in judgement of facial affect: a multivariate analysis of recognition errors.

The present paper investigated recognition errors in affective judgement of facial emotional expressions. Twenty-eight females and sixteen males participated in the study. The results showed that in both males and females emotional displays could be correctly classified, but females had a higher rate of correct classification; males were more likely to have difficulty distinguishing one emotion from another. Females rated emotions identically regardless of whether the emotion was displayed by a male or female face. Furthermore, the two-factor structure of emotion, based on a valence and an arousal dimension, was only present for female subjects. These results further extend our knowledge about gender differences in affective information processing.

Adult↗
PubMed2000

Autonomic changes during orthostasis: a time-frequency analysis.

The transition between sitting and standing represents a period of dynamic changes in cardiac autonomic control. Previous research using heart rate (HR) has suggested a biphasic HR response from sitting to standing with an initial increase in HR followed by an HR decrease before stabilizing at a level above the sitting level. These HR changes have been interpreted as mediated by sympathetic nervous system (SNS) activity. However, more direct measures of cardiac autonomic control have not been investigated in an active orthostasis paradigm. This is due in part to the requirement of stationarity for traditional spectral analytic techniques. In the present study, time-frequency analysis was used to assess the relative contributions of sympathetic and parasympathetic nervous system activity to the cardiac autonomic control during the transition of orthostasis. We examined the heart rate time series during the transition between sitting and standing, and the 60 s prior and the 60 s following the transition. The high frequency component of the HR spectra (an index of parasympathetic activity) decreased sharply at the point of transition and remained depressed relative to the low frequency component (an index of sympathetic activity). These results suggest that time-frequency analysis may be a useful technique to examine non-stationary time series. Furthermore, the transition of orthostasis may be mediated more via parasympathetic activity than by sympathetic activity.

Adult↗
PubMed2000

A system for the ambulatory recording and analysis of nonlinear heart rate dynamics.

The study of cardiac dynamics is a topic of great clinic and experimental concern. However, the ability to apply methods from the emerging field of nonlinear dynamics to cardiac time series has been limited by the demand for large amounts of relatively artifact-free data. Both the ability to collect such data and the capacity to analysis such large data sets represents limits. In the present paper we describe a system that allows for the collection of large amounts of high quality data and the analysis of large data sets. The recording system consists of a miniature, single-module electrocardiogram-recording device. This module consists of an integrated three-electrode device that is attached to the chest of the subject. A low power 8-bit micro-controller detects the R-spike and stores the time between R-spikes in milliseconds on a 512 KB EEPROM. This system can record continuously for over four days. The output of this system is down-loaded to a PC and the RR intervals fed to a suite of digital signal processing programs. Among other things, estimates of Approximate Entropy and Poincaire plots are generated. This system will expand the capability of researchers and clinicians to investigate nonlinear cardiac dynamics in ambulatory subjects.

Heart Rate↗
PubMed2000

Autonomic control of the heart during circular breathing.

The analysis of heart rate variability (HRV) has become an increasingly popular method for probing the autonomic nervous system (ANS). A number of specific periodicities have been identified in the spectra of cardiac time series. One major mechanism involved in a number of these periodicities is respiratory modulation of neural traffic to the heart. One respiratory maneuver that has never been investigated is circular breathing. This technique is employed by wind musicians to produce an uninterrupted stream of sound without pauses for breathing. The current study examined the effects of circular breathing on ANS control of the heart in a highly proficient professional musician. Results indicated that circular breathing both with and without producing a sound was associated with altered autonomic control of the heart. Specifically, circular breathing was associated with increases in heart rate and decreases in high frequency HRV. This high frequency HRV has been most closely linked with respiratory sinus arrhythmia and respiratory modulation of vagal neural traffic. We conclude that the examination of novel breathing maneuvers may help to illuminate the role of respiratory modulation of HRV.

Autonomic Nervous System↗
PubMed2000

Phasic heart period reactions to cued threat and nonthreat stimuli in generalized anxiety disorder.

The hallmark of generalized anxiety disorder (GAD) is chronic uncontrollable worry. A preattentive bias toward threat cues and hypervigilance may support this ongoing state of apprehension. A study was conducted to bridge the attentional and physiological underpinnings of GAD by examining phasic heart period (HP) responses to cued threat and nonthreat stimuli. Thirty-three GAD clients and 33 nonanxious control participants engaged in an S1-S2 procedure that employed cued threat and nonthreat word stimuli, during which phasic HP reactions were recorded. As compared with the control group, the GAD group showed (1) smaller cardiac orienting responses and impaired habituation of cardiac orienting to neutral words, (2) HR acceleration in response to threat words, and (3) a conditioned anticipatory HR deceleration to threat words over repeated trials. The cardiac-autonomic underpinnings of GAD appear to rigidly maintain precognitive defensive responses against threat. This portrayal is discussed in the context of an integrative model that depicts diminished global adaptive variability in GAD.

Adult↗
PubMed1999

A meta-analysis of fibromyalgia treatment interventions.

OBJECTIVE: To evaluate and compare the efficacy of pharmacological and nonpharmacological treatments of fibromyalgia syndrome (FMS). METHODS: This meta-analysis of 49 fibromyalgia treatment outcome studies assessed the efficacy of pharmacological and nonpharmacological treatment across four types of outcome measures-physical status, self-report of FMS symptoms, psychological status, and daily functioning. RESULTS: After controlling for study design, antidepressants resulted in improvements on physical status and self-report of FMS symptoms. All nonpharmacological treatments were associated with significant improvements in all four categories of outcome measures with the exception that physically-based treatment (primarily exercise) did not significantly improve daily functioning. When compared, nonpharmacological treatment appears to be more efficacious in improving self-report of FMS symptoms than pharmacological treatment alone. A similar trend was suggested for functional measures. CONCLUSION: The optimal intervention for FMS would include nonpharmacological treatments, specifically exercise and cognitive-behavioral therapy, in addition to appropriate medication management as needed for sleep and pain symptoms.

Activities of Daily Living↗
PubMed1999

Relations among psychological trauma, dissociative phenomena, and trauma-related distress: a review and integration.

Recently, there has been a resurgence of interest in relations among psychological trauma, dissociative phenomena, and various forms of trauma-related distress that has spawned a prolific amount of research. To date, a relatively comprehensive review of this recent research is lacking. Thus, this paper provides such a review to help summarize and synthesize recent findings, illuminate study limitations, and offer suggestions for future research. In general, findings have revealed fairly strong and consistent relations among the constructs of trauma, dissociation, and trauma-related distress (e.g., posttraumatic stress disorder, borderline personality disorder, bulimia); individuals who have experienced a traumatic event are more likely to dissociate than individuals who have not, and individuals who experience more dissociative phenomena are more likely to also experience higher levels of trauma-related distress. It is theorized here that dissociative phenomena and subsequent trauma-related distress may relate to fears about death and fears about loss or lack of control above and beyond the occurrence of the traumatic event itself. Such fears about death and loss/lack of control may also help differentiate traumatized individuals who psychologically suffer to varying degrees. Possible functions of dissociation in response to trauma and in relation to forms of trauma-related distress are considered and discussed.

Acute Disease↗
PubMed1999

Measuring post-traumatic stress: a psychometric evaluation of symptom--and coping questionnaires based on a Norwegian sample.

The purpose of this study was to evaluate the psychometric characteristics of the Norweigian versions of the Impact of Event Scale, the Post Traumatic Stress Scale-10 item version and General Coping Questionnaire-30 item version. A group of 40 male and 56 female medical students was tested one week and four months after having started dissection of cadavers for the first time. The results showed that all scales had good internal consistency and test-retest reliability. The student sample scored lower on the IES and PTSS-10 than comparable groups of traumatized subjects. A gender difference emerged, with female subjects scoring higher than male subjects. The factor analysis of the instruments indicated good construct validity for the symptom scales. The analysis of content validity related to DSM IV criteria indicated that the IES and PTSS-10 may have some limitations in their predictive validity of PTSD. Taken together, the three scales have shown good psychometric properties and could be used in future research and clinical work.

Adaptation, Psychological↗
PubMed1998

Heart period variability and depressive symptoms: gender differences.

BACKGROUND: Deceased heart period variability has been associated with cardiac events and depressive symptoms; however, the results of studies are not unequivocal. We hypothesize that gender differences in the various study samples may have contributed to the lack of uniformity of findings. METHODS: Time and frequency domain measures of heart period variability during a 5-min resting baseline were examined in 15 depressed (8 female) and 11 nondepressed (6 female) college students. RESULTS: Both time and frequency domain measures indicated an interaction between gender and depressive symptoms, such that depressed male subjects showed less heart period variability, whereas depressed female subjects showed more heart period variability compared to their nondepressed counterparts. CONCLUSIONS: These results suggest that future studies investigating the relationship between heart period variability and depressive symptoms examine gender differences.

Adult↗
PubMed1998

Disease and family contributors to adaptation in juvenile rheumatoid arthritis and juvenile diabetes.

OBJECTIVE: Research in the areas of pediatric rheumatology and pediatric chronic illness has emphasized comprehensive models of adaptation involving risk and resistance factors. This study examined adaptation, within this framework, among a large sample of children with chronic illness and children without chronic illness. METHODS: A comprehensive battery of adaptation measures was administered to a sample of 107 children with juvenile rheumatoid arthritis, 114 children with insulin-dependent diabetes mellitus, and 88 healthy controls. RESULTS: Medical diagnosis was associated with mothers' depression and a composite measure of parental (mother and father) distress and passive coping. Children's emotional and behavioral functioning was not related to medical diagnosis, but mothers' depression and parental distress were associated with child behavior problems. CONCLUSION: Because parental distress was associated with child functioning, interventions to ameliorate parental distress may have beneficial effects on the children's behavior and on parents' reactions to their children.

Adaptation, Psychological↗
PubMed1998

Anger inhibition, cardiovascular recovery, and vagal function: a model of the link between hostility and cardiovascular disease.

A model of the association between hostility and cardiovascular disease (CVD) is proposed based upon anger inhibition, slow cardiovascular recovery, and low parasympathetic activity (vagal tone). This model is opposed to the more conventional model that emphasizes anger expression, cardiovascular reactivity, and high sympathetic tone. We argue that in social reality, incidences of anger inhibition outnumber incidences of anger expression to a great extent, irrespective of preferred expression style. Moreover, slow cardiovascular recovery, rather than high reactivity, may be the mechanism underlying the CVD risk associated with anger inhibition. Both anger inhibition and slow cardiovascular recovery are associated with a persistently low vagal tone. Thus, the anger inhibition/vagal inhibition model seems more consistent with the actual nature of anger in daily life and with the known cardiovascular control mechanisms. The model may better account for the chronic pathophysiological state that is believed to lead to CVD. Importantly, an experimental inhibition/recovery paradigm might also allow to test potential behavioral and cognitive accelerators of cardiovascular recovery. As an example of an important socially-mediated health risk that may be elucidated using the anger inhibition/vagal inhibition model, we discuss Black-White differences that have been found in CVD.

Adaptation, Psychological↗