Bernhard Dahme

The Unpleasantness of Perceived Dyspnea Is Processed in the Anterior Insula and Amygdala

RATIONALE The subjective perception of dyspnea, which is an impairing symptom in various cardiopulmonary diseases, consists of sensory (intensity) and affective aspects (unpleasantness). However, little is known about the cortical processing of the perception of dyspnea. OBJECTIVES To investigate the cortical areas associated with the processing of the affective unpleasantness of perceived dyspnea. METHODS Brain imaging study using functional magnetic resonance imaging in 14 healthy volunteers. MEASUREMENTS AND MAIN RESULTS Dyspnea was induced by inspiratory resistive loaded breathing with concomitant positive and negative emotional stimulation by viewing standardized emotional picture series. The blood oxygen level-dependent contrast was measured as an index of local neuronal activity while respiration was continuously monitored. Negative emotional stimulation during loaded breathing was associated with higher unpleasantness of perceived dyspnea when compared with loaded breathing with concomitant positive emotional stimulation (P < 0.05). The levels of intensity of perceived dyspnea, respiratory responses, and load magnitude were similar between both conditions. Higher unpleasantness of dyspnea was associated with neuronal activations in the limbic system-that is, in the right anterior insula and in the right amygdala (respective Z values = 3.93 and 3.15; P < 0.05). CONCLUSIONS The results of the present brain imaging study suggest that the unpleasantness of subjectively perceived dyspnea is processed in the right human anterior insula and amygdala.

Dyspnea and pain share emotion-related brain network.

The early detection of stimuli signalling threat to an organism is a crucial evolutionary advantage. For example, the perception of aversive bodily sensations such as dyspnea and pain strongly motivates fast adaptive behaviour to ensure survival. Their similarly threatening and motivating characters led to the speculation that both sensations are mediated by common brain areas, which has also been suggested by neuroimaging studies on either dyspnea or pain. By using functional magnetic resonance imaging (fMRI), we formally tested this hypothesis and compared the cortical processing of perceived heat pain and resistive load induced dyspnea in the same group of participants. Here we show that the perception of both aversive sensations is processed in similar brain areas including the insula, dorsal anterior cingulate cortex, amygdala and medial thalamus. These areas have a documented role in the processing of emotions such as fear and anxiety. Thus, the current study highlights the role of a common emotion-related human brain network which underlies the perception of aversive bodily sensations such as dyspnea and pain. This network seems crucial for translating the threatening character of different bodily signals into behavioural consequences that promote survival.

Implementation and interpretation of respiratory sinus arrhythmia measures in psychosomatic medicine: practice against better evidence?

Respiratory sinus arrhythmia (RSA) or high-frequency heart rate variability has been widely used as a noninvasive measure of cardiac vagal tone. However, their dependency on both respiration rate and tidal volume is largely ignored. Only a minority of studies published in Psychosomatic Medicine in recent years has implemented precautions for controlling respiration rate in RSA measures, and tidal volume effects were only rarely addressed. We discuss methodologic issues related to respiratory control methods and present data that demonstrate that both respiration rate and tidal volume contribute substantially to the within-individual RSA variance under conditions of variable breathing, with tidal volume contributing up to one third beyond respiration rate. Finally, we outline a respiratory control method for the time-domain index of RSA and review research pertaining to its reliability, validity, and experimental application. HRV = heart rate variability; pCO2 = partial pressure of carbon dioxide; RSA = respiratory sinus arrhythmia; RR = respiration rate; TTOT = total respiratory cycle time; VT = tidal volume.

Guidelines for mechanical lung function measurements in psychophysiology

Studies in psychophysiology and behavioral medicine have uncovered associations among psychological processes, behavior, and lung function. However, methodological issues specific to the measurement of mechanical lung function have rarely been discussed. This report presents an overview of the physiology, techniques, and experimental methods of mechanical lung function measurements relevant to this research context. Techniques to measure lung volumes, airflow, airway resistance, respiratory resistance, and airflow perception are introduced and discussed. Confounding factors such as ventilation, medication, environmental factors, physical activity, and instructional and experimenter effects are outlined, and issues specific to children and clinical groups are discussed. Recommendations are presented to increase the degree of standardization in the research application and publication of mechanical lung function measurements in psychophysiology.

A short goal-pursuit intervention to improve physical capacity: A randomized clinical trial in chronic back pain patients

&NA; The present study tested a short intervention using goal‐pursuit strategies to increase physical capacity in pain patients. Sixty chronic back pain patients were randomly assigned to intervention or control conditions. Both groups followed a 3‐week conventional back pain program at an outpatient back pain center. Instead of routine treatment, the intervention group received a one‐hour intervention consisting of a combination of (a) a goal‐setting strategy (i.e., mental contrasting, MC) aimed at commitment to improved physical capacity, (b) a short cognitive behavioral therapy‐oriented problem‐solving approach (CBT) to help patients overcome the obstacles associated with improving physical capacity, and (c) a goal‐pursuit strategy, i.e., implementation intentions (II) aimed at performing physical exercise regularly. At two follow‐ups (3 weeks after discharge and 3 months after returning home) the MCII‐CBT group had increased its physical capacity significantly more than the control group as measured by both behavioral measures (ergometer, lifting) and subjective ratings. Findings are discussed with relation to the use of the intervention as a specific treatment to increase chronic pain patients’ motivation to be physically active.

Specificity of cognitive biases in patients with current depression and remitted depression and in patients with asthma

BACKGROUND Previous studies have demonstrated a specific cognitive bias for sad stimuli in currently depressed patients; little is known, however, about whether this bias persists after recovery from the depressive episode. Depression is frequently observed in patients with asthma and is associated with a worse course of the disease. Given these high rates of co-morbidity, we could expect to observe a similar bias towards sad stimuli in patients with asthma. METHOD We therefore examined cognitive biases in memory and attention in 20 currently and 20 formerly depressed participants, 20 never-depressed patients diagnosed with asthma, and 20 healthy control participants. All participants completed three cognitive tasks: the self-referential encoding and incidental recall task, the emotion face dot-probe task and the emotional Stroop task. RESULTS Compared with healthy participants, currently and formerly depressed participants, but not patients with asthma, exhibited specific biases for sad stimuli. CONCLUSIONS These results suggest that cognitive biases are evident in depression even after recovery from an acute episode but are not found in never-depressed patients with asthma.

Down-Regulation of Insular Cortex Responses to Dyspnea and Pain in Asthma

RATIONALE Dyspnea is the impairing cardinal symptom of asthma but its accurate perception is also crucial for timely initiation of treatment. However, the underlying brain mechanisms of perceived dyspnea in patients with asthma are unknown. OBJECTIVES To study brain mechanisms of dyspnea in asthma. METHODS By using functional magnetic resonance imaging we compared the neuronal responses to experimentally induced dyspnea in patients with asthma and healthy controls. These brain activations were compared with neuronal responses evoked by pain to study neuronal generalization processes to another, similarly unpleasant, physiological sensation. MEASUREMENTS AND MAIN RESULTS While lying in the scanner, fourteen patients with mild-to-moderate asthma and fourteen matched healthy controls repeatedly underwent conditions of mild dyspnea, severe dyspnea, mild pain and severe pain. Dyspnea was induced by resistive loaded breathing. Heat pain of similar intensity was induced by a contact thermode. Whereas the sensory intensity of both sensations was rated similar by patients and controls, ratings of the affective unpleasantness of dyspnea and pain were reduced in patients. This perceptual difference was mirrored by reduced insular cortex activity, but increased activity in the periaqueductal gray (PAG) in patients during both increased dyspnea and pain. Connectivity analyses showed that asthma-specific down-regulation of the insular cortex during dyspnea and pain was moderated by increased PAG activity. CONCLUSIONS The results suggest a down-regulation of affect-related insular cortex activity by the PAG during perceived dyspnea and pain in patients with asthma. This might represent a neuronal habituation mechanism reducing the affective unpleasantness of dyspnea in asthma, which generalizes to other unpleasant physiological sensations such as pain.

Relationship between Cannabis Use, Schizotypal Traits, and Cognitive Function in Healthy Subjects

This research examined the relationship between cannabis use and schizotypal features. A sample of cannabis users (n = 20) was compared with a matched control group (n = 20). All participants were male students of the University of Hamburg. Subjects completed the Perceptual Aberration Scale and the Schizotypal Personality Questionnaire. A Negative Priming procedure and the Trail Making Test were carried out. A urine sample was obtained from each subject. Cannabis users exceeded controls in schizotypy scores and showed impaired neuropsychological parameters. Only within the cannabis group schizotypy scores correlated with neuropsychological parameters. Furthermore, cannabis users reported more often high-risk factors than controls. These findings indicate that among cannabis users there is an increased number of subjects with schizotypal features; schizotypal subjects seem to be more likely to use cannabis than the general population. Therefore, cannabis use may be a vulnerability indicator for schizophrenia.

Sensory and affective aspects of dyspnea contribute differentially to the Borg scale's measurement of dyspnea.

Background:Recent research has shown that distinct dimensions in the perception of dyspnea can be differentiated; however, most studies to date have only used a global rating scale for the measurement of this sensation. Objectives: This study examined the different influence of sensory and affective aspects of perceived dyspnea on the commonly used Borg scale, which measures the global perception of dyspnea. Methods: Dyspnea was induced in 16 healthy volunteers (mean age 26.2 ± 6.3 years) by breathing through an inspiratory resistive load (3.57 kPa/l/s) in two experimental conditions (attention and distraction). After each of the two conditions the experienced intensity (i.e., sensory dimension) and unpleasantness (i.e., affective dimension) of dyspnea were rated on separate visual analog scales (VAS), followed by a global rating of dyspnea on the Borg scale. Hierarchical multiple linear regression models were calculated to analyze the predictive validity of VAS ratings of intensity and unpleasantness on the Borg scale ratings. Results: When subjects attended to their breathing, only VAS intensity scores showed a significant influence on Borg scale ratings (p < 0.05). In contrast, only the VAS unpleasantness scores showed a significant influence on Borg scale ratings (p < 0.05) when subjects were distracted. Conclusions: These findings show that sensory and affective aspects of perceived dyspnea differentially influence the global measure of dyspnea as determined by the Borg scale. A differentiation between these aspects in future studies through the use of separate rating scales could yield more detailed information on the perception and report of dyspnea.

BODY IMAGE IN EATING DISORDERS AND ANALYSIS OF ITS RELEVANCE: A PRELIMINARY STUDY

The purpose of the present study was to assess body perception in eating disorders and its meaning in therapy. A total of 44 patients, 25 bulimia nervosa and 19 anorexia nervosa, admitted at a specialized in-patient treatment center participated in the present study. Body size estimation procedures (video-distortion and image-marking techniques) and self-report questionnaires were used for the assessment. No significant differences were found in actual body size estimation between the two eating disorder groups, either before or after therapy. It emerged after therapy that the outcome was not related to body size estimation. These findings suggest that there is no evidence for a serious impairment of body perception (size estimation) in eating-disordered patients, but rather for a disturbance in the emotional aspect of body image, as expressed in negative body attitudes. Body size perception does not appear to be a predictor of treatment outcome in eating disorders.