Does the heart know what the ears hear? A heart rate analysis of auditory selective attention

Between- and within-channel auditory selective attention were examined by presenting subjects with tone pips randomly to opposite ears; some pips had a slightly different pitch. Subjects were instructed to count rare, deviant tone pips at one ear and ignore all input to the other ear. Heart rate was sampled twice: once for the attended tone pips and once for the nonattended stimulus series. Heart rate responded differently to attended tone pips. While subjects were waiting for the rare stimulus to occur, heart rate slowed until the deviant stimulus was detected, which was followed by heart rate acceleration. Anticipatory heart rate deceleration was largely absent for nonatended series, and rare tone pips presented at the nonattended ear were not followed by acceleratory recovery. All tone pips elicited cardiac cycle time effects, that is, stimuli presented at short delays after the R wave prolonged the concurrent interbeat interval more than stimuli presented later. The cardiac cycle time effect was not altered by stimulus relevance (attended vs. nonattended) or significance (standard vs. rare). These results suggest that all stimuli receive preliminary perceptual analysis, but only attended stimuli are processed for further evaluation.     

Heart rate and sustained attention during childhood: Age changes in anticipatory heart rate, primary bradycardia, and respiratory sinus arrhythmia

This study examined age changes in three aspects of heart rate responsivity elicited in an auditory oddball task; anticipatory heart rate change, primary bradycardia, and respiratory sinus arrhythmia. Three age groups (5-, 7-, and 9-year-old boys) were presented with series of target (15%) and standard (85%) tones. The results were consistent with the findings reported previously in the adult literature. Heart rate decreased in anticipation of the target tone. The morphology of anticipatory deceleration was somewhat different for the 5-year-olds compared to the older children. Stimuli presented during the early part of the cardiac cycle induced added deceleration, but this primary bradycardia did not differ between age groups. Respiratory sinus arrhythmia did not discriminate between age groups but was suppressed during the performance of the oddball task relative to base level. It was concluded that these three aspects of heart rate responsivity show developmental constancy rather than change.     

The effect of folic acid on the homocysteine metabolism in human umbilical vein endothelial cells (HUVECs)

Mild hyperhomocysteinaemia is associated with increased risk for vascular disease. We studied homocysteine export from human umbilical vein endothelial cells (HUVECs) by measuring total homocysteine (tHcy) concentrations in the culture medium. Under standard culture conditions tHcy concentrations in the HUVEC culture medium increased by constant amounts after 24, 48 and 72 h [mean = 2.5 (SD ± 0.7) μmol L⁻¹ homocysteine every 24 h]. As the cells are the only source of homocysteine increase in the culture medium, we designate this as homocysteine export from HUVEC. Folic acid supplementation to the culture medium lowered the homocysteine export in a dose-dependent manner. Methyl-tetrahydrofolate (MeTHF) and folinic acid (a stable precursor of MeTHF) were in this respect about 10 times more effective than folic acid. A 50% reduction in the homocysteine export was seen with 10–30 nmol L⁻¹ MeTHF supplementation; reduction to almost zero was seen with 100–300 nmol L⁻¹ MeTHF. Additions to the culture medium of the other vitamins involved in the homocysteine metabolism, such as vitamin B₁₂, vitamin B₆ and flavin adenine dinucleotide, did not show any effect on homocysteine export. Because homocysteine export reflects an imbalance in the homocysteine metabolism, our observations showed a susceptible dependency of this metabolism on folic acid in endothelial cells.     

A Generic Toxicokinetic Model for Persistent Lipophilic Compounds in Humans: An Application to TCDD

This paper discusses a toxicokinetic model describing the distributionof TCDD in the human body during a lifetime. The model dividesthe body into several physiological compartments, their weightsbeing functions of age. Ingested TCDD is instantaneously distributedover all compartments according to their lipid content. Theliver eliminates TCDD from the body by a first-order process.Intake depends on age, as estimated from food consumption surveydata combined with data on TCDD concentrations in various foods.It is shown that historical changes in intake, due to changesin environmental concentrations and in dietary habits, shouldbe taken into account as well. Elimination rate and bioavailability,the only unknown parameters in the model, were estimated bycalibrating the model to human data on internal concentrations.The generic formulation of the model makes it suitable for slowlyeliminated lipophilic compounds in general.     

Heart rate variability: Origins, methods, and interpretive caveats

Components of heart rate variability have attracted considerable attention in psychology and medicine and have become important dependent measures in psychophysiology and behavioral medicine. Quantification and interpretation of heart rate variability, however, remain complex issues and are fraught with pitfalls. The present report (a) examines the physiological origins and mechanisms of heart rate variability, (b) considers quantitative approaches to measurement, and (c) highlights important caveats in the interpretation of heart rate variability. Summary guidelines for research in this area are outlined, and suggestions and prospects for future developments are considered.     

Phase-sensitive interaction of cardiac and respiratory timing in humans

We asked whether the heart rate response to respiratory change varied as a function of timing within the cardiac cycle. Respiratory and electrocardiographic data were collected from seven men and seven women during three weekly sessions under conditions of normal and visually paced breathing. Results revealed that, when inspiration began sooner than 500 ms before the subsequent heart beat, inspiration had little effect on the subsequent interbeat interval. However, the timing of the subsequent beat was accelerated when inspiration began later than 450 ms before this heart beat. Similar relationships were observed for expiratory onset. Results were not attributable to volitional control or rate of breathing. The modulation of respiratory sinus arrhythmia by the timing of respiratory events in the cardiac cycle has implications for the role of vagal control in the synchronization of heart rate with respiratory and behavioral actions.     

Access to cancer services – do culture and ethnicity make a difference?

This module discusses the diverse cultural needs of people affected by cancer and how those needs can be assessed and met. The UK experience with Black or Minority Ethnic (BME) communities will be used to explore the issues of awareness of and detection of cancer.