The Psychological Significance of Task-Induced Tonic Changes in Somatic and Autonomic Activity

Two experiments tested the view that task-induced autonomic-somatic gradient parallelism does exist and that the steeper the physiological gradients, over the course of a task, the more involved the subject and the greater the effort. Thirty-three male subjects performed easy and difficult versions of a continuous reaction time task. In both experiments the difficult task prompted steeper electromyographic (EMG) activity gradients than did the easy version. Scores on heart rate (HR) and skin conductance did not show clear gradients. However, task-dependent effort was positively related to the magnitude of the initial HR acceleration and to the steepness of the EMG gradient. The autonomic-somatic coupling hypothesis of Obrist did not explain the results. Instead, evidence for ventilatory-somatic parallelism was found.     

Respiratory Patterns as Predictors of Laughter

Earlier research on respiratory patterns indicates that they are sensitive to emotional processes. Abdominal and thoracic patterns were therefore used as predictors of laughter responses in 25 subjects participating in an entertainment situation. The abdominal respiratory body circumference changes (the abdominal amplitude) of the women predicted their laughter responses; the greater the abdominal amplitudes during the entertainment period, the more frequent and enduring were their laughter responses. No prediction was obtained by the respiratory patterns of men. The results suggest that respiratory patterns are sensitive indicators of laughter response habits in women only. The variability of tonus in the abdominal muscles was suggested to be of particular importance to the results, i. e. great variability yields frequent and enduring laughter responses in women.     

Does hypertension protect against chronic musculoskeletal complaints? The Nord-Trøndelag Health Study

BACKGROUND: Although an inverse relationship between pain sensitivity and hypertension has been described, it is still unknown whether hypertension may protect against chronic musculoskeletal complaints (MSCs). The aim of this study was to evaluate the relationship between blood pressure (BP) and prevalence of chronic MSCs at various anatomical sites. METHODS: Two consecutive public health studies within the county of Nord-Tr?ndelag, Norway, were conducted between January 5, 1984, and February 15, 1986 (Nord-Tr?ndelag Health Study [HUNT] 1), and from August 1995 to June 1997 (HUNT-2). Among 46 901 adults who participated in both surveys, 24 127 (51.4%) in HUNT-2 who reported MSCs continuously for at least 3 months during the past year were defined as having chronic MSCs. The prevalence of chronic MSCs was estimated using multiple logistic regression, with odds ratio and 95% confidence interval as measures of association with systolic and diastolic BP. RESULTS: A high systolic and diastolic BP was associated with a 10% to 60% lower prevalence of chronic MSCs, and there was a strong linear trend (P<.001) of decreasing prevalence of chronic MSCs with increasing BP values. The findings were remarkably consistent at all anatomical sites, for both sexes, across all age groups, and for systolic and diastolic BP measured in HUNT-1 and HUNT-2. CONCLUSIONS: Individuals with a high BP had a lower prevalence of chronic MSCs than individuals with a normal BP. One possible explanation may be the phenomenon of hypertension-associated hypalgesia, due to an interaction between the cardiovascular and pain regulatory systems. The effect of antihypertensive medication on this interaction should be evaluated in further studies.     

Attention to affective pictures in closed head injury: event-related brain potentials and cardiac responses

We examined whether closed head injury patients show altered patterns of selective attention to stimulus categories that naturally evoke differential responses in healthy people. Self-reported rating and electrophysiological (event-related potentials [ERPs], heart rate [HR]) responses to affective pictures were studied in patients with mild head injury (n = 20; CT/MRI negative), in patients with predominantly frontal brain lesions (n = 12; CT/MRI confirmed), and in healthy controls (n = 20). Affective valence similarly modulated HR and ERP responses in all groups, but group differences occurred that were independent of picture valence. The attenuation of P3-slow wave amplitudes in the mild head injury group indicates a reduction in the engagement of attentional resources to the task. In contrast, the general enhancement of ERP amplitudes at occipital sites in the group with primarily frontal brain injury may reflect disinhibition of input at sensory receptive areas, possibly due to a deficit in top-down modulation performed by anterior control systems.     

Cardiac and somatic activation in the continuous perceptual-motor task: the significance of threat and serious-mindedness

The significance of serious-mindedness and task-contingent threat for cardiac and somatic activation were tested in a mixed design. Ten serious-minded and 10 playful state-dominant subjects were recruited from a larger sample to form extreme-groups according to their responses to the Telic Dominance Scale. They all performed a continuous perceptual-motor task with and without threat of aversive electric shock as punishment for inferior performance (counterbalanced). Results supported the following conclusions: serious-mindedness was associated with passive forearm EMG activity, whereas playfulness was related to active forearm EMG activity. Threat of shock interacted with serious-mindedness to cause particularily high HR with threat versus low HR in the no-threat treatment. Error-scores and scores on perceived task difficulty did not explain group differences in physiological activation. The results were discussed in relation to a hypothesis of cardiac-somatic uncoupling during effortful active coping, the pyramidal and extrapyramidal pathways to the skeletal muscles, and to effort expended in the serious-minded and playful motivational states.     

Wide gastric antrum and low vagal tone in patients with diabetes mellitus type 1 compared to patients with functional dyspepsia and healthy individuals

Autonomous neuropathy in patients with diabetes is associated with dysmotility and abdominal discomfort. The disturbances resemble to some extent those seen in patients with functional dyspepsia. To gain further insight into the disorders, we compared patients with long-standing diabetes, patients with functional dyspepsia, and healthy individuals with respect to abdominal symptoms, width of gastric antral area, and autonomic nerve function. We investigated 42 type I diabetic outpatients by structured interview for abdominal discomfort, ultrasonography of the gastric antrum, assessment of vagal and sympathetic nerve function by respiratory sinus arrhythmia and skin conductance, and measurement of blood sugar and HbAlc. Immediately after a standard meal of soup with meat, 21 (50%) of the 42 patients with diabetes complained of abdominal discomfort (pain, bloating, fullness), which was significantly less frequent (95% CI of difference 0.03–0.5) than previously seen in patients with functional dyspepsia (76%), and significantly more frequent (95% CI of difference 0.3–0.6) than that seen in healthy individuals (4%). Bloating was the most marked postprandial complaint. Mean fasting antral area was significantly wider in patients with diabetes (mean 4.9 cm²,sd 1.7) compared to healthy individuals (mean 3.5 cm²,sd 1.2), 95% CI of difference 0.6–2.2 cm². Mean postprandial antral area was 14.8 cm² (sd 4.6) in the patients with diabetes, which is insignificantly wider than in patients with functional dyspepsia (mean 13.0 cm²,sd 4.0) but significantly wider (95% CI of difference 1.9–6.5 cm²) than that seen in healthy individuals (mean 10.6 cm²,sd 3.8). The mean respiratory sinus arrhythmia was 0.7 beats/min (sd 0.7) in the patients with diabetes, which was insignificantly lower than that seen in patients with functional dyspepsia (2.1 beats/min,sd 4.5), and significantly lower (99% CI of difference 3.8–7.1 beats/min) compared to healthy individuals (6.2 beats/min,sd 3.8). It is concluded that patients with diabetes have a wider gastric antrum and more discomfort after a meal than healthy individuals. Compared to patients with functional dyspepsia, patients with diabetes have a wider postprandial antrum but fewer symptoms. The very low vagal tone seen in patients with diabetes may play an important role in the pathogenesis of their gastric motility disturbance and postprandial abdominal discomfort.This work was supported by the National Research Council in Norway and Janssen Pharma, Norway.     

Breathing exercises with vagal biofeedback may benefit patients with functional dyspepsia

OBJECTIVE: Many patients with functional dyspepsia (FD) have postprandial symptoms, impaired gastric accommodation and low vagal tone. The aim of this study was to improve vagal tone, and thereby also drinking capacity, intragastric volume and quality of life, using breathing exercises with vagal biofeedback. MATERIAL AND METHODS: Forty FD patients were randomized to either a biofeedback group or a control group. The patients received similar information and care. Patients in the biofeedback group were trained in breathing exercises, 6 breaths/min, 5 min each day for 4 weeks, using specially designed software for vagal biofeedback. Effect variables included maximal drinking capacity using a drink test (Toro clear meat soup 100 ml/min), intragastric volume at maximal drinking capacity, respiratory sinus arrhythmia (RSA), skin conductance (SC) and dyspepsia-related quality of life scores. RESULTS: Drinking capacity and quality of life improved significantly more in the biofeedback group than in the control group (p=0.02 and p=0.01) without any significant change in baseline autonomic activity (RSA and SC) or intragastric volume. After the treatment period, RSA during breathing exercises was significantly correlated to drinking capacity (r=0.6, p=0.008). CONCLUSIONS: Breathing exercises with vagal biofeedback increased drinking capacity and improved quality of life in FD patients, but did not improve baseline vagal tone.