STUDIES OF AUTONOMIC BALANCE: A SUMMARY

A summary of a series of studies of autonomic balance and differential patterns of autonomic function in normal and hospitalized adult males, covering the period of 1944 to the present.     

Effects of gramine on energy metabolism of rat and bovine mitochondria

The indole alkaloid gramine is found in several plant families. Its effects on mammalian mitochondria and submitochondrial particles were studied. Low concentrations of gramine slightly stimulated basal electron transport, totally inhibited the Ca2+-induced respiratory control and partially abolished the enhancement of 8-anilino-1-naphthalene sulfonate fluorescence induced by proton translocation coupled to ATP hydrolysis or to succinate oxidation. At higher concentrations gramine inhibited specifically the electron transport at the level of Complex I of the respiratory chain. The I50 values (2-6 mM) were dependent on the presence of uncouplers. Higher concentrations of the alkaloid also inhibited coupled succinate oxidation and ATP hydrolysis (I50 = 10 mM). Possible explanations for these effects are discussed.     

Acute effects on heart rate variability when exposed to hand transmitted vibration and noise

Objectives This study investigates possible acute effects on heart rate variability (HRV) when people are exposed to hand transmitted vibration and noise individually and simultaneously. Methods Ten male and 10 female subjects were recruited by advertisement. Subjects completed a questionnaire concerning their work environment, general health, medication, hearing, and physical activity level. The test started with the subject resting for 15 min while sitting down. After resting, they were exposed to one of four exposure conditions: (1) only vibration; (2) only noise; (3) both noise and vibration; or (4) a control condition of exposure to the static load only. All four exposures lasted 15 min and the resting time between the exposures was 30 min. A continuous electrocardiogram (ECG) signal was recorded and the following HRV parameters were calculated: total spectral power (P _TOT); the spectral power of the very low frequency component (P _VLF); the low frequency component (P _LF); the high frequency component (P _HF); and the ratio LF/HF. Results Exposure to only vibration resulted in a lower P _TOT compared to static load, whereas exposure to only noise resulted in a higher P _TOT. The mean values of P _TOT, P _VLF, P _LF, and P _HF were lowest during exposure to vibration and simultaneous exposure to vibration and noise. Conclusions Exposure to vibration and/or noise acutely affects HRV compared to standing without these exposures. Being exposed to vibration only and being exposed to noise only seem to generate opposite effects. Compared to no exposure, P _TOT was reduced during vibration exposure and increased during noise exposure.     

The psychobiology of emotional development: The case for examining sociocultural processes

Psychobiological techniques to assess emotional responding have revolutionized the field of emotional development in recent decades by equipping researchers with the tools to quantify children's emotional reactivity and regulation more directly than behavioral approaches allow. Knowledge gained from the incorporation of methods spanning levels of analysis has been substantial, yet many open questions remain. In this prospective review, we (a) describe the major conceptual and empirical advances that have resulted from this methodological innovation, and (b) lay out a case for what we view as the most pressing challenge for the next decades of research into the psychobiology of emotional development: focusing empirical efforts toward understanding the implications of the broader sociocultural contexts in which children develop that shape the psychobiology of emotion. Thus, this review integrates previous knowledge about the psychobiology of emotion with a forward-looking set of recommendations for incorporating sociocultural processes into future investigations.     

Groupitizing modifies neural coding of numerosity

Numerical estimation of arrays of objects is faster and more accurate when items can be clustered into groups, a phenomenon termed “groupitizing.” Grouping can facilitate segregation into subitizable “chunks,” each easily estimated, then summed. The current study investigates whether spatial grouping of arrays drives specific neural responses during numerical estimation, reflecting strategies such as exact calculation and fact retrieval. Fourteen adults were scanned with fMRI while estimating either the numerosity or shape of arrays of items, either randomly distributed or spatially grouped. Numerosity estimation of both classes of stimuli elicited common activation of a right lateralized frontoparietal network. Grouped stimuli additionally recruited regions in the left hemisphere and bilaterally in the angular gyrus. Multivariate pattern analysis showed that classifiers trained with the pattern of neural activations read out from parietal regions, but not from the primary visual areas, can decode different numerosities both within and across spatial arrangements. The behavioral numerical acuity correlated with the decoding performance of the parietal but not with occipital regions. Overall, this experiment suggests that the estimation of grouped stimuli relies on the approximate number system for numerosity estimation, but additionally recruits regions involved in calculation.     

The association between supportive social ties and autonomic nervous system function—differences between family ties and friendship ties in a cohort of older adults

Supportive family and friendship ties can serve different functions and thus might show different associations with an individual’s health. Particularly, older adults might show varying health benefits of different types of supportive ties depending on their marital and retirement status. Our aim is to analyze relationships between different types of supportive social ties and autonomic nervous system (ANS) function, a physiological indicator of health that can help to establish the biological plausibility of the association—measured by heart rate variability (HRV). We present cross-sectional linear regression analyses of a German cohort of community-dwelling older adults (2008–2010; n = 1,548; mean age = 68.7 years). Our findings indicate that supportive friendship ties show significant positive associations (i.e., higher HRV) in individuals that are either not married or above retirement age. Supportive family ties show significant positive associations in individuals below retirement age. Significant results vanish or are reduced after accounting for behavioral/physical and psychological/cognitive indicators. We conclude that programs supporting the development or maintenance of friendship ties might be especially beneficial in unmarried older adults and adults above retirement age.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10433-021-00638-2.     

Autonomic Nervous System Dysfunction: JACC Focus Seminar

Autonomic nervous system control of the heart is a dynamic process in both health and disease. A multilevel neural network is responsible for control of chronotropy, lusitropy, dromotropy, and inotropy. Intrinsic autonomic dysfunction arises from diseases that directly affect the autonomic nerves, such as diabetes mellitus and the syndromes of primary autonomic failure. Extrinsic autonomic dysfunction reflects the changes in autonomic function that are secondarily induced by cardiac or other disease. An array of tests interrogate various aspects of cardiac autonomic control in either resting conditions or with physiological perturbations from resting conditions. The prognostic significance of these assessments have been well established. Clinical usefulness has not been established, and the precise mechanistic link to mortality is less well established. Further efforts are required to develop optimal approaches to delineate cardiac autonomic dysfunction and its adverse effects to develop tools that can be used to guide clinical decision-making.     

Baroreflex modulation during sleep and in obstructive sleep apnea syndrome

This review focuses on the complex integration between cardiovascular reflexes and central autonomic influences controlling physiological sleep-dependent changes in arterial blood pressure and heart rate. A brief introduction on the anatomic and functional organization of the arterial baroreflex and the methods available to assess its function in humans is followed by an analysis of the functional interaction between autonomic nervous system and sleep mechanisms at the highest levels of brain organization. An insight into these interactions is important to shed light on the physiopathology of the most frequent complications of obstructive sleep apnea syndrome, such as sustained arterial hypertension, and excessive daytime sleepiness.     

Orthostatic hypotension is associated with new-onset atrial fibrillation: Systemic review and meta-analysis

IntroductionOrthostatic hypotension (OH) is common among elderly patients. Its presence may herald severe underlying comorbidities and be associated with a higher risk of mortality. Interestingly, recent studies suggest that OH is associated with new-onset atrial fibrillation (AF). However, a systematic review and meta-analysis of the literature has not been performed. We assessed the association between AF and OH through a systematic review of the literature and a meta-analysis.MethodsWe comprehensively searched the databases of MEDLINE and EMBASE from inception to November 2018. Published prospective or retrospective cohort studies that compared new-onset AF between male patients with and without OH were included. Data from each study were combined using the random-effects, generic inverse-variance method of DerSimonian and Laird to calculate risk ratios and 95% confidence intervals.ResultsFour studies from October 2010 to March 2018 were included in the meta-analysis involving 76,963 subjects (of which 3318 were diagnosed with OH). The presence of OH was associated with new-onset AF (pooled risk ratio 1.48; 95% confidence interval [1.21, 1.81], p?< 0.001; I2 = 69.4%). In hypertensive patients, analysis revealed an association between OH and the occurrence of new-onset AF (OR 1.46; 95% CI [1.27, 1.68], p < 0.001 with I2 = 0).ConclusionsOH was associated with new-onset AF up to 1.5-fold compared with those subjects without OH. The interplay between OH and AF is likely bidirectional.