Effects of respiratory depth and rate on HR and TWA: an indirect assessment of the respiratory confound in cognitive task difficulty manipulations

Manipulations of respiration depth and rate were performed in order to observe their effects on HR and TWA. The shallow breathing conditions were considered respiratorily similar to the conditions existing during the performance of an iterative subtraction task. Although significant HR increases and TWA decreases were noted in the deep breathing conditions, the changes in the shallow conditions were not of sufficient magnitude to account for the HR increases and TWA decreases which have been observed during the performance of subtraction tasks. Therefore it appears that respiratory confounds are not responsible for the effects that have been observed in previous studies.     

Effects of electrode placement on direction of T-wave amplitude changes in psychophysiological studies

Psychophysiological studies, which measure small changes in T-wave amplitude (TWA) induced by behavioral manipulations, usually employ a single electrode placement for obtaining the ECG. The present study varied electrode placement (EP) within subjects among three EPs that have been reported in the literature (a lead-II limb placement, and two chest placements) to determine whether, as has been claimed, the direction of TWA changes can be changed by varying EP. Both HR and TWA were monitored in 24 males during the Baseline, Listen, and Task phases of an iterative subtraction task. The EP variation did not affect the direction of TWA change. Reliable TWA attenuation accompanied by HR acceleration was observed in all leads.     

Phasic Cardiac Reactivity to Psychological Stress as a Function of Aerobic Fitness Level

Cardiovascular adjustments to physical exertion are known to be affected by aerobic fitness level. This raises the possibility that the cardiovascular responses associated with psychological stress may also be related to aerobic fitness. This study was undertaken to determine if phasic cardiac reactivity to stress would be affected by aerobic fitness level, and to make inferences regarding the autonomic mechanisms which might mediate such an effect. Twenty-four males were given a standard physical fitness test and then divided into high and low aerobic fitness level groups. Within two weeks of this assessment, the heart rate and electrocardiographic T-wave amplitude responses of these subjects were monitored during the performance of hard and easy versions of a mental arithmetic task. Analysis of the heart rate data revealed no aerobic fitness level effect. There was, however, greater T-wave amplitude attenuation in the low as compared to the high aerobic fitness level group on hard trials. This pattern of results suggests that psychologically-elicited sympathetic cardiac reactivity is reduced by enhanced aerobic fitness level.     

Human Pavlovian HR-decelerative conditioning with negative tilt as US: evidence of vagal and sympathetic influences on the UR in dogs

Following a review of studies employing negative tilt in human Pavlovian conditioning of heart rate (HR) deceleration (Furedy et al, in press), this paper reports data based on animal subjects on such physiological aspects of the decelerative unconditioned response (UR) as the degree of vagal involvement. Five anesthetized dogs underwent 90 degrees negative body tilts pre- and postbilateral vagotomy, while interbeat interval (IBI), left ventricular pressure (LVP) and its first derivative, d(LVP)/dt, which is a measure of sympathetic cardiac drive, were recorded. Consistent with the vagal interpretation of the tilt-induced decelerative UR, the results indicated that vagotomy markedly changed the tilt-induced bradycardic reflex from a fast-recruiting, large-magnitude (over 45%), and sustained (throughout the 20-27-s tilt) IBI increase, to slower-recruiting, and markedly smaller (less than 5%) IBI increase. However, there was also evidence of an initial sympathetic excitation of about 5 s, as indicated by a 45% increase in d(LVP)/dt, which returned to baseline level by 9 s following tilt onset. Vagotomy increased this tilt-induced sympathetic excitation to about 100%, and it remained at above 70% throughout the tilt. Prevagotomy LVP showed a slight (about 10%) and delayed (about 6 s following tilt onset) depressor response, which was eliminated by vagotomy. Finally, unaveraged data from individual dogs suggested that prevagotomy, LVP changes preceded IBI changes. Regarding implications of these results for human HR deceleration-inducing preparations, we conclude that the different physiological mechanisms that accompany and/or produce a given change in HR need continuing investigation with multiple dependent physiological variables (which are assessed for topographical differences), and in both human and animal preparations.     

Self-schema in irritable bowel syndrome and depression

Some investigators have suggested that irritable bowel syndrome (IBS) represents a physiologic expression of an affective disorder. This study investigated whether IBS patients differed in their self-schema from depressed patients. Self-schema refers to a cognitive framework of the individual's beliefs, attitudes, and self-perceptions which is stored in memory and which influences incoming information. The sample consisted of 21 IBS patients, 21 psychiatric outpatients with major depression (MD), and 19 normal controls. All groups were age matched. Subjects completed a structured psychiatric interview (Diagnostic Interview Schedule (DIS) and a Beck Depression Inventory (BDI), in addition to a test of self-schema, which involved rating and recall of a variety of "depressed" and "nondepressed" content adjectives. Consistent with previous work on self-schema, the MD group recalled significantly more depressed adjectives rated under the self-referent task than the Control group (p less than 0.05) and, also, the IBS group (p less than 0.05). Most striking was the finding that a subgroup of IBS patients who met criteria for MD (43% of the sample) recalled significantly more self-referent nondepressed words (and less self-referent depressed words) than the MD group (p less than 0.05). In other words, IBS patients with MD do not view themselves as depressed. These findings suggest that while some IBS and depressed psychiatric outpatients may share depressive symptoms, these groups can be differentiated by their self-schema.     

A systematic review of parents’ experiences and information needs related to their child’s urinary tract infection

Objective

As a first step toward the development of an animated video and infographic to increase parents’ knowledge of pediatric urinary tract infections (UTIs), we conducted a systematic review of their experiences and information needs.

Human Pavlovian HR decelerative conditioning with negative tilt as US: a review of some S-R, stimulus-substitution evidence

Interest in human Pavlovian heart rate (HR) conditioning with conventional shock and loud noise unconditional stimuli has declined, as measured by reports in the literature. Accompanying this decline have been the following views: (a) that HR should be abandoned as a psychophysiological index of the psychological (learning) process of Pavlovian conditioning; (b) that, following psychology's shift to a more cognitive emphasis, the self-regulation (S-R), stimulus-substitution view of pavlovian conditioning is wrong, because there is no equivalence in direction between shock- and loud noise-induced HR-accelerative unconditional response and the conditional response. This paper reviews recent reports of human Pavlovian conditioning of HR deceleration with negative tilt as the unconditional stimulus. The results support an S-R, stimulus-substitution interpretation of conditioning. In addition, these studies have potential therapeutic application in the teaching of (medically desirable) HR deceleration, especially when Pavlovian procedures are combined with instrumental (biofeedback) ones. However, such physiological aspects of the decelerative unconditioned response as the degree of vagal involvement are difficult to investigate in the human preparation.