The role of the vagus nerve during fetal development and its relationship with the environment

The autonomic nervous system (ANS) regulatory capacity begins before birth as the sympathetic and parasympathetic activity contributes significantly to the fetus' development. Several studies have shown how vagus nerve is involved in many vital processes during fetal, perinatal and postnatal life: from the regulation of inflammation through the anti-inflammatory cholinergic pathway, which may affect the functioning of each organ, to the production of hormones involved in bioenergetic metabolism. In addition, the vagus nerve has been recognized as the primary afferent pathway capable of transmitting information to the brain from every organ of the body. Therefore, this hypothesis paper aims to review the development of ANS during fetal and perinatal life, focusing particularly on the vagus nerve, to identify possible "critical windows" that could impact its maturation. These "critical windows" could help clinicians know when to monitor fetuses to effectively assess the developmental status of both ANS and specifically the vagus nerve. In addition, this paper will focus on which factors (i.e. fetal characteristics and behaviors, maternal lifestyle and pathologies, placental health and dysfunction, labor, incubator conditions, and drug exposure) may have an impact on the development of the vagus during the above-mentioned "critical window" and how. This analysis could help clinicians and stakeholders define precise guidelines for improving the management of fetuses and newborns, particularly to reduce the potential adverse environmental impacts on ANS development that may lead to persistent long-term consequences. Since the development of ANS and the vagus influence have been shown to be reflected in cardiac variability, this paper will rely in particular on studies using fetal heart rate variability (fHRV) to monitor the continued growth and health of both animal and human fetuses.Comment: Word count: 16,009 Tables: 1 Figures:

Transcutaneous Auricular Vagus Nerve Stimulation (TAVNS): Long-Term Effect on Neurodevelopment and Sensory Performance

Infants who do not succeed at early feeding are likely discharged from the nursery with a gastrostomy tube (G-tube), putting them at risk for worse neurodevelopmental and sensory outcomes than infants who achieve full oral feeds. This study aims to investigate the impact of Non-invasive transcutaneous auricular vagal nerve stimulation (taVNS) on infants\u27 early motor development and long-term neurodevelopmental sensory performance at 18 months. Besides the observed feeding improvement using taVNS paired with bottle-feeding, we explore if pre-treatment total STEP scores\u27 is able to predict response to taVNS intervention. The pre-treatment total STEP scores did not contribute to the prediction model significantly. Then, we looked at the long-term effect of early taVNS treatment in both neurodevelopmental and sensory outcomes at 18 months follow-up. We found that infants who responded to early taVNS treatment when paired with bottle-feeding had better overall neurodevelopmental outcomes than non- responders. We also found that responders had significantly better typical scores in the general sensory section, and had more typical average mean scores in almost all the sensory profile sections than non-responders. These preliminary results are encouraging of the use of taVNS. Future studies can include randomization of active and control taVNS intervention with larger sample size

Attachment and Internalizing and Externalizing Problems in Adolescence: Exploring the Mediating Role of Physiological Self-Regulation Capacity

Internalizing and externalizing problems impact functioning and health in adolescence. Therefore, understanding risk and protective factors related to these behaviors is of practical interest. The proposed study examined the relationship between parent-adolescent attachment security, self-regulation capacity, and internalizing and externalizing problems. Previous studies have supported prospective links between parent-child attachment security and self-regulation capacities. Similarly, self-regulation is as a protective factor from internalizing and externalizing problems. This study proposed a mediation model combining these findings. It was hypothesized that youth with stronger parent-adolescent attachment security would demonstrate fewer internalizing and externalizing problems, and that this relationship would be mediated by better physiological self-regulation capacity among youth with stronger attachment. Attachment was measured through parent report of their own attachment behaviors, and child report of attachment security with their parents. Results supported the hypothesis that greater parent-adolescent attachment security would be related to fewer internalizing (cross-sectional β = -3.38, p \u3c .00; longitudinal β = -4.34, p \u3c .00) and externalizing problems (cross-sectional β = -3.63, p \u3c .00; longitudinal β = -3.92, p \u3c .00). However, results including physiological self-regulation capacity were unexpected. Child rated attachment security was not significantly related to regulation capacity (β = -.16, p = 0.28); while, greater parent attachment behaviors were significantly related to poorer, not better, physiological self-regulation capacity (β = -.31, p = 0.02). Mediation analyses revealed two models trending towards significance; though no models reached significance based on a 95% confidence interval. Models trending toward significance included the effect of parent attachment behaviors on externalizing problems through physiological self-regulation capacity prospectively (β = .18, 95% CI [-.02, .57]) and concurrently (β = -.24, 95% CI [-.80, .08]). However, within these models, greater parent attachment behaviors were related to lower, not greater, physiological self-regulation capacity, making theoretical interpretation of findings less clear. Interpretation and implications of these findings are discussed

Microbiome-Gut-Brain Axis: A Pathway for Improving Brainstem Serotonin Homeostasis and Successful Autoresuscitation in SIDS-A Novel Hypothesis.

Sudden infant death syndrome (SIDS) continues to be a major public health issue. Following its major decline since the Back to Sleep campaign, the incidence of SIDS has plateaued, with an annual incidence of about 1,500 SIDS-related deaths in the United States and thousands more throughout the world. The etiology of SIDS, the major cause of postneonatal mortality in the western world, is still poorly understood. Although sleeping in prone position is a major risk factor, SIDS continues to occur even in the supine sleeping position. The triple-risk model of Filiano and Kinney emphasizes the interaction between a susceptible infant during a critical developmental period and stressor/s in the pathogenesis of SIDS. Recent evidence ranges from dysregulated autonomic control to findings of altered neurochemistry, especially the serotonergic system that plays an important role in brainstem cardiorespiratory/thermoregulatory centers. Brainstem serotonin (5-HT) and tryptophan hydroxylase-2 (TPH-2) levels have been shown to be lower in SIDS, supporting the evidence that defects in the medullary serotonergic system play a significant role in SIDS. Pathogenic bacteria and their enterotoxins have been associated with SIDS, although no direct evidence has been established. We present a new hypothesis that the infant\u27s gut microbiome, and/or its metabolites, by its direct effects on the gut enterochromaffin cells, stimulates the afferent gut vagal endings by releasing serotonin (paracrine effect), optimizing autoresuscitation by modulating brainstem 5-HT levels through the microbiome-gut-brain axis, thus playing a significant role in SIDS during the critical period of gut flora development and vulnerability to SIDS. The shared similarities between various risk factors for SIDS and their relationship with the infant gut microbiome support our hypothesis. Comprehensive gut-microbiome studies are required to test our hypothesis

An exploration of swallowing stimulation in the infant

The purpose of this study was twofold: to determine the effects of two types of non-invasive, peripheral sensory stimulation on the frequency of infant swallowing and to explore the cortical activation patterns in response to stimulation in the somatosensory and motor regions of the brain during infancy, between 2-4 months and 7-9 months of age. The two different forms of mechanical stimulation investigated include pacifier stimulation to the lips and oral cavity and vibrotactile stimulation via the external throat area to the laryngeal tissues. The study represents a prospective, repeated experimental research design. Investigators utilized an accelerometer and an inductive plethysmography system to identify swallowing events and functional near-infrared spectroscopy (NIRS), a non-invasive cortical optical-imaging technique, to cortical responses to the peripheral stimulation conditions by measuring the hemodynamic responses in cortical oral-motor and sensorimotor regions. A repeated-measures ANOVA was performed on the participants’ swallowing frequency data with and without the stimulation conditions. The results indicated a significant difference (p \u3c .001) among the three conditions (no stimulation, pacifier stimulation, and vibrotactile stimulation), with pairwise comparisons indicating that the pacifier and vibrotactile conditions significantly (p \u3c .001) increased the infants’ swallowing frequency compared to swallowing frequency without stimulation. Swallowing frequency did not differ between the pacifier and vibrotactile conditions (p \u3e .05). NIRS recordings were obtained on only a few subjects for technical reasons. NIRS pilot data changes in blood flow occurred during the pacifier and vibrotactile stimulation conditions in a few infants. Overall findings suggest that both pacifier and vibrotactile stimulation can serve to up-regulate the frequency of swallowing in normal infants. Non-nutritive pacifier stimulation may be beneficial for increasing the frequency of swallowing in infants in addition to the known benefits of aiding in sucking skills development. Vibrotactile stimulation represents an alternative or complementary intervention for increasing the frequency of swallowing in infants that may not interfere with the process of oral intake. The current study continues to collect data for normal infants and should be explored in infants with disordered swallowing, particularly in the neonatal intensive care unit

Inflammation and Autonomic Function

Inflammation is generally a temporary and limited condition but may lead to a chronic one if immune and physiological homeostasis are disrupted. The autonomic nervous system has an important role in the short- and, also, long-term regulation of homeostasis and, thus, on inflammation. Autonomic modulation in acute and chronic inflammation has been implicated with a sympathetic interference in the earlier stages of the inflammatory process and the activation of the vagal inflammatory reflex to regulate innate immune responses and cytokine functional effects in longer processes. The present review focuses on the autonomic mechanisms controlling proinflammatory responses, and we will discuss novel therapeutic options linked to autonomic modulation for diseases associated with a chronic inflammatory condition such as sepsis

Respiratory Control: Central and Peripheral Mechanisms

Understanding of the respiratory control system has been greatly improved by technological and methodological advances. This volume integrates results from many perspectives, brings together diverse approaches to the investigations, and represents important additions to the field of neural control of breathing. Topics include membrane properties of respiratory neurons, in vitro studies of respiratory control, chemical neuroanatomy, central integration of respiratory afferents, modulation of respiratory pattern by peripheral afferents, respiratory chemoreception, development of respiratory control, behavioral control of breathing, and human ventilatory control. Forty-seven experts in the field report research and discuss novel issues facing future investigations in this collection of papers from an international conference of nearly two hundred leading scientists held in October 1990. This research is of vital importance to respiratory physiologists and those in neurosciences and neurobiology who work with integrative sensory and motor systems and is pertinent to both basic and clinical investigations. Respiratory Control is destined to be widely cited because of the strength of the contributors and the dearth of similar works. The four editors are affiliated with the University of Kentucky: Dexter F. Speck is associate professor of physiology and biophysics, Michael S. Dekin is assistant professor of biological sciences, W. Robert Revelette is research scientist of physiology and biophysics, and Donald T. Frazier is professor and chairman of physiology and biophysics. Experts in the field report current research and discuss novel issues facing future investigations. —SciTech Book Newshttps://uknowledge.uky.edu/upk_biology/1002/thumbnail.jp