Disinhibitory psychopathology in male adolescents: discriminating conduct disorder from attention-deficit/hyperactivity disorder through concurrent assessment of multiple autonomic states.

T. P. Beauchaine recently proposed a model of autonomic nervous system functioning that predicts divergent patterns of psychophysiological responding across disorders of disinhibition. This model was tested by comparing groups of male adolescents with attention-deficit/hyperactivity disorder (ADHD) and attention-deficit/hyperactivity disorder plus conduct disorder (CD/ADHD) with controls while performing a repetitive motor task in which rewards were administered and removed across trials. Participants then watched a videotaped peer conflict. Electrodermal responding (EDR), cardiac pre-ejection period (PEP), and respiratory sinus arrhythmia (RSA) were monitored. Compared with controls, the ADHD and CD/ADHD participants exhibited reduced EDR. The CD/ADHD group was differentiated from the ADHD and control groups on PEP and from the control group on RSA. Findings are discussed in terms of the motivational and regulational systems indexed. Implications for understanding rates of comorbidity between CD and ADHD are considered.

Nonconscious fear conditioning, visceral perception, and the development of gut feelings.

When people are presented with backward-masked images of fear-relevant stimuli and only some of these images are paired consistently with electric shocks, they can predict the occurrence of shocks even though they do not consciously know which images they have seen. We postulated that they may use the perception of visceral cues from the conditional fear response to facilitate the prediction of shocks. In this study, ability to detect heartbeats was used to index sensitivity to visceral cues. The results showed that subjects who could detect their heartbeats performed better than chance in predicting whether or not they would receive a shock during the conditioning task. The findings support the notion that hunches, or "gut feelings," are based in part on the perception of visceral cues.

Vagal rebound and recovery from psychological stress.

OBJECTIVE: To characterize cardiovascular recovery and examine the possible relationship of vagal activity and reflexes to risk for heart disease. METHODS: Subjects performed cold pressor and mental arithmetic tasks. Heart rate, heart period variability, and pre-ejection period were obtained for 1 minute before, during, and after each task (Experiment 1). In the second experiment, subjects performed a Stroop color-word task and a mental arithmetic task. Heart rate, heart period variability, blood pressure, and baroreflex sensitivity were obtained during the 5-minute baseline, task, and recovery periods (Experiment 2). RESULTS: In Experiment 1, heart rate during recovery was lower than baseline despite continued pre-ejection period shortening, whereas recovery heart period variability was higher than baseline. In Experiment 2, blood pressure increased throughout the session. However, recovery heart rate after mental arithmetic was lower than baseline heart rate, and heart period variability was higher during both recovery periods than during baseline. Vagal rebound, a sharp increase in variability in the first minute of recovery, was reduced in men in Experiment 1 and in individuals with a family history of cardiovascular disease in Experiment 2 and was associated with degree of change in baroreflex sensitivity between task and rest. CONCLUSIONS: Cardiovascular recovery from stress is associated with increased vagal modulation despite residual sympathetic activation. Vagal rebound may be involved in mechanisms resetting the baroreflex sensitivity at the onset and offset of stress. Diminished vagal rebound during recovery from stress is associated with standard risk factors for cardiovascular disease. The results support an association between attenuated vagal reflexes and risk for cardiovascular disease.

Breast-feeding and maternal cardiovascular function.

Two studies examined the effects of breast-feeding on maternal cardiovascular function. In the first experiment, groups of breast-feeding and bottle-feeding women were compared on preejection period (PEP), heart rate (HR), cardiac output (CO), and total peripheral resistance (TPR) recorded for 1-min periods before and during standard laboratory stressors. Compared with bottle-feeders, breast-feeders had higher CO throughout the session, and greater decreases in CO and increases in TPR during cold pressor. In the second experiment, HR and blood pressure (BP) were compared before and after one breast-feeding and one bottle-feeding session in a within-subjects design. Both feeding methods increased BP but decreased HR, and systolic BP was higher for the breast-feeding than the bottle-feeding condition. Both studies support the notion that breast-feeding alters maternal cardiovascular function, possibly through the actions of oxytocin.

Classical conditioning of the human blood pressure response.

The object of this experiment was to demonstrate that blood pressure responses could be classically conditioned in human subjects and to describe the topography of the conditioned response. Despite clear evidence for classical blood pressure conditioning in animals there is little evidence concerning a clear demonstration of the phenomenon in human subjects, and no description of the form of the conditioned response. A 'neutral' 8-s 70-db tone (CS) was paired with a 500-ms electric shock (UCS) in a delay conditioning paradigm. Conditioned subjects were compared to a control group that received the CS and UCS on a truly random schedule. The subjects in the conditioning group showed a conditioned blood pressure response that emerged during the last 4 s of the 8-s CS. The results differ from those obtained from animals, where the CR typically emerges during the first half of the CS. These data may have implications for the role of learning in hypertensive disorders.

The effects of epinephrine administration on impedance cardiographic measures of cardiovascular function.

The effects of epinephrine administration on cardiovascular function were examined in 26 men who were given a bolus injection of either 1:10,000 epinephrine hydrochloride or physiological saline. Impedance cardiographic and continuous blood pressure measures were recorded during a 2-min pre-injection baseline and in the post-injection period. Compared to a saline control, epinephrine elicited greater shortening of heart period, pre-ejection period, and the R-B interval; greater increases in cardiac output, stroke volume, dZ/dt amplitude, Heather Index, and systolic and diastolic pressures; and greater decreases in total peripheral resistance (all P < 0.05). Left ventricular ejection time and the Q-R interval were not affected. The results indicate that inotropic indices that are readily measured by impedance cardiography should be considered as important non-invasive indices of adrenergically mediated responses to stress.

A test of the validity of the method of constant stimuli as an index of heartbeat detection.

A heartbeat detection task, based on the method of constant stimuli (MCS), requires participants to judge which of a series of tones presented at different delays following a heartbeat are coincident with the heartbeat. Two experiments were conducted to test the validity of the MCS in assessing individual differences in the ability to detect heartbeat sensations. The first experiment found the MCS to be valid, in that about one-third of subjects met the criterion for classification as heartbeat detectors when the tones were presented with respect to their actual heartbeats, but only one subject met the criterion when the tones were presented with respect to previously recorded heartbeats. The second experiment manipulated the timing of the comparison intervals (i.e., R + 100-600 ms rather than R + 0-500 ms) to examine the validity of the median R-wave to tone interval as an index of temporal location of perceived heartbeats, and found it to be a valid index.

Response bias affects perceptual asymmetry scores and performance measures on a dichotic listening task.

A dichotic listening paradigm discussed by Sidtis and Bryden (Neuropsychologia, 1978, 16, 627-632) allows one to present non-verbal as well as verbal material. This paradigm also permits signal-detection analyses to separate response biases from discrimination abilities. The present study used Sidtis' (Neuropsychologia, 1981, 19, 103-112) Complex Tone Task as an example of the paradigm. Employing signal-detection analyses, we demonstrated that commonly used performance and asymmetry indices are confounded by response bias. Several indices based on signal-detection measures are suggested to replace current widely used measures. As pointed out by Bryden and Sprott (Neuropsychologia, 1981, 19, 571-581), currently the usefulness of a perceptual asymmetry score is mainly determined by mathematical and statistical properties rather than by a theoretical framework. Thus, the choice of a particular index based on signal-detection theory is arbitrary. The present results and those of Katsuki et al. (Journal of Speech and Hearing Research, 1984, 27, 444-448) suggest that the confounding effect of response bias may be present in a variety of experiments investigating lateral processing.

Visceral perception, anhedonia, and emotion.

Few investigators have attempted to examine empirically the relationship between perception of autonomic arousal and emotional state. According to Jamesian theory, individuals who are more aware of their visceral activity should demonstrate greater affective response to emotion-laden stimuli than individuals who are not viscerally perceptive. Therefore, certain groups of 'unemotional' subjects, such as anhedonics, may report fewer or less intense emotional experiences due to an attenuation or lack of autonomic feedback. Results from studies by Katkin (Psychophysiology, 22, (1985) 125-137) suggest that there is a relationship between induced sympathetic arousal, the perception of that arousal, and the self-report of emotional experience. The present study sought to expand upon these findings by comparing visceral perception (i.e. heartbeat detection) performance and a multi-component assessment of emotion in normal and anhedonic subjects. No correlation was found between anhedonia and visceral perception; however, anhedonics were significantly different from normals across several measures of heart rate, self-report, and facial expressions in response to emotion-eliciting slides, with anhedonics consistently showing emotional hypo-responsiveness. Additionally, subjects who were able to perceive their own heartbeats were found to be more facially expressive than poor perceivers.

Event-related potentials to airway occlusion in young and old subjects.

Event-related potentials (ERPs) were recorded to both inspiratory and expiratory airway occlusion in young (21-28 years) and old (55-67 years) subjects under both attend and ignore conditions. Early and late components of the ERP (N1, P2, N2, P3) were observed to both types of occlusions in both conditions. Variations in these components were consistent in both direction and degree with those observed in oddball tasks employing exteroceptive stimuli. ERPs for breathing may serve to clarify sensory attributes of respiratory stimuli in humans and to identify central processing abnormalities in patient populations.

The relationship between cardiovascular reactivity and heartbeat detection.

This experiment tested the hypothesis that inotropic cardiovascular reactivity to stress is related to performance on heartbeat discrimination tasks. The experiment also compared the efficacy of a specific modification of two popular heartbeat discrimination paradigms, Whitehead's and Katkin's. Subjects were 48 male undergraduates who performed both discrimination tasks and then were subjected to mental arithmetic stress. Results indicated that high cardiovascular reactors were better detectors than low reactors. Results also indicated that subjects performed better on the modified Whitehead task than on the modified Katkin task.

Psychological, situational, and gender predictors of cardiovascular reactivity to stress: a multivariate approach.

This study examined whether relationships between anger expression, hostility, social evaluative anxiety, and a presumed mechanism for coronary heart disease development, cardiovascular reactivity (CVR) to stress, are moderated by stress situation and gender and whether such relationships are attenuated by inadequate assessments. Subjects (47 men, 47 women) were assigned randomly to either a Harassment or a Social Evaluation condition, under which they performed a reaction time task. SBP, DBP, and HR measures were recorded during baseline and task. Multiple regression analyses indicated that expressed anger was related to CVR only among men in the Harassment condition; that hostile men who express anger showed the most CVR across situations, and that the traits assessed here did not predict CVR among women. Results suggest that assessments of coronary-risk and interventions to reduce risk may need to take into account attitudes, styles of emotional expression, environmental factors, and gender.

Signal-detection outcomes on heartbeat and respiratory resistance detection tasks in male and female subjects.

Male and female subjects were compared on heartbeat, respiratory resistance, and light-tone signal-detection tasks. Subjects judged whether a series of 10 tones was coincident with their heartbeats; whether an external load added to the airway was either present or absent during targeted inspiratory cycles; and whether a series of 10 light flashes was matched with auditory tones presented following a fixed delay of either 50 or 100 ms. Nonparametric indices of perceptual sensitivity and response bias indicated that men were more sensitive than women on the resistive load task (p < .05) and on the heartbeat task (p = .07). Performance on the light-tone task was virtually identical. All subjects used a stricter criterion on the respiratory resistance task than on either the heartbeat or the light-tone task; women employed a stricter criterion than men on the heartbeat task. The gender differences may be understood in terms of lateralization of central processing of somesthetic sensory information.

Test-retest reliability of inotropic and chronotropic measures of cardiac reactivity.

This study evaluated the retest reliability of a number of inotropic and chronotropic indexes of cardiovascular reactivity to mental arithmetic stress over a 1-week interval. Differential habituation effects of the dependent measures were also assessed. 15 male and 15 female undergraduate Ss were administered a mental arithmetic task (serial subtractions by 13 from a 4-digit number) for 1-min on two successive weeks while their electrocardiogram and impedance cardiogram were recorded. Dependent measures included HR, PEP, HI, SV and CO. Results indicate that all dependent measures were reliable.

Anger expression, hostility, anxiety, and patterns of cardiac reactivity to stress.

The majority of studies investigating the relationships between psychological characteristics and cardiovascular reactivity to stress use a research strategy in which discrete traits are evaluated in isolation. The present study examined the effects of additive and/or interactive relationships among traits on cardiac reactivity to a mental arithmetic task. In addition, impedance cardiographic techniques were employed to examine potential relationships between such psychological traits and a specific measure--pre-ejection period (PEP)--of sympathic influence on the heart. Forty-nine undergraduate men performed a mental arithmetic task while continuous measures of PEP and interbeat interval (IBI) were collected. The subjects then completed questionnaires measuring anger expression, hostility, and trait anxiety. Analyses of variance (ANOVAs) showed a significant main effect for anger-out on PEP change from baseline, but not for IBI. Results also showed that anger-in interacted with anger-out and hostility to affect both PEP and IBI changes significantly. Other results indicated that subjects in the high anger-in/low anger-out and high anger-in/low hostility groups did not show significant PEP change, although they nevertheless showed significant IBI change. These results highlight the importance of the consideration of interactions among traits in predicting cardiac reactivity and of the importance of measuring specific indexes of sympathetic arousal.

Individual differences in cortical evoked potentials as a function of heartbeat detection ability.

Much work has been done to assess individual differences in the ability to detect visceral activity, and most of this work has focused on heartbeat detection ability. This experiment attempted to determine if some underlying cortical event is associated with heartbeat detection ability, and further, to assess whether this cortical event is lateralized to the right hemisphere. Event-related cortical potentials, time-locked to the EKG R-wave and averaged over 400 samples, were studied at Fz, Cz, F7, and F8 in 12 subjects. The primary dependent measure of heartbeat detection accuracy was the standard deviation of the mean temporal latency, measured from peak EKG R-waves to the subjects' report of physical sensation of heartbeats. A significant relationship was found between the amplitudes of event related potentials (ERPs) in the right hemisphere and heartbeat detection accuracy.

Cardiovascular asymmetries and cardiac perception.

Two strategies for evaluating the lateral specificity of cardiac sensory innervation were reviewed: (1) electrophysiological recording of cardiac-relevant cortical activity; and (2) behavioral assessment of right versus left differences in cardiac sensory perception. Electrophysiological data from two different laboratories suggest strongly that there is a link between cardiac events and cortical response to stimulation, but only for the right hemisphere. Two experiments from our laboratory suggest that there is a complex relationship among cerebral lateral preference, assessed by conjugate lateral eye movements, arousal, and individual differences in accuracy of self-perception of heart beats. The data, overall, suggest that the right hemisphere is involved specifically in heartbeat perception.

Psychophysiological evidence for cerebral laterality effects in a high-risk sample of students with subsyndromal bipolar depressive disorder.

The authors compared bilateral recordings of electrodermal activity and conjugate lateral eye movements in two groups (10 men and 10 women each) of college students: high-risk nonpatients with subsyndromal depression and normal control subjects. Like acutely depressed patients, the high-risk subjects showed smaller right- than left-hand skin conductance response amplitudes to neutral tones. This group also showed a bias toward left-tending conjugate lateral eye movements in response to various cognitive problems. Control subjects showed symmetrical responses on all electrodermal activity measures and question-specific conjugate lateral eye movements. These data are tentatively interpreted as reflecting right-hemisphere hyperexcitability in affective illness.