Learning of food preferences: mechanisms and implications for obesity & metabolic diseases

Omnivores, including rodents and humans, compose their diets from a wide variety of potential foods. Beyond the guidance of a few basic orosensory biases such as attraction to sweet and avoidance of bitter, they have limited innate dietary knowledge and must learn to prefer foods based on their flavors and postoral effects. This review focuses on postoral nutrient sensing and signaling as an essential part of the reward system that shapes preferences for the associated flavors of foods. We discuss the extensive array of sensors in the gastrointestinal system and the vagal pathways conveying information about ingested nutrients to the brain. Earlier studies of vagal contributions were limited by nonselective methods that could not easily distinguish the contributions of subsets of vagal afferents. Recent advances in technique have generated substantial new details on sugar- and fat-responsive signaling pathways. We explain methods for conditioning flavor preferences and their use in evaluating gut–brain communication. The SGLT1 intestinal sugar sensor is important in sugar conditioning; the critical sensors for fat are less certain, though GPR40 and 120 fatty acid sensors have been implicated. Ongoing work points to particular vagal pathways to brain reward areas. An implication for obesity treatment is that bariatric surgery may alter vagal function.

Self-Reported Emotion Regulation Is Associated With Response to Test of Cardiac Vagal Function

Parasympathetic function and emotional self-regulation (ESR) share neuroanatomic structures. Based on Porges’ Polyvagal Theory and the Neurovisceral Integration Model (NIM), we compared vagally mediated heart-rate variability (vmHRV) with psychometrically assessed ESR. We hypothesized that vmHRV and ESR would be associated during rest, a vagal function test, and recovery from that test. A significant association would justify the psychometric measuring of parasympathetic health, which is less burdensome than its psychophysiological assessment. Two hundred thirteen healthy males (aged: 18–26 years, M = 20.29 years) took part in the present study. They completed the Emotion Regulation Questionnaire (ERQ) and underwent the Cold Face Test (CFT) for 4 min wearing ambulatory electrocardiograms. A High frequency (HF) band was used as a measure of vmHRV before, during, and after the CFT. Associations between the HF band and ESR were analyzed with partial rank correlations. There was no significant association between ERQ scores and the response to the CFT itself. But there was an almost significant association between the ERQ scale Cognitive Appraisal and baseline vmHRV, and a significant association between Cognitive Appraisal and cardiac recovery from the CFT, that is, participants with higher scores on that ESR scale revealed a tendency to exhibit greater vmHRV during baseline and they exhibited greater vagal withdrawal during recovery from the CFT. Cognitive appraisal as a psychometrically assessed emotion regulatory process was reflected in a more flexible parasympathetic activity (i.e., better cardiac vagal health) during recovery from an exclusively physiological stressor. This lends convergent validity to self-reported emotion regulation, and justification for its use as a measure of ESR as a trait, offering further support for the Polyvagal Theory and NIM.

Moving Beyond Disciplinary Silos Towards a Transdisciplinary Model of Wellbeing: An Invited Review

The construct of wellbeing has been criticised as a neoliberal construction of western individualism that ignores wider systemic issues such as inequality and anthropogenic climate change. Accordingly, there have been increasing calls for a broader conceptualisation of wellbeing. Here we impose an interpretative framework on previously published literature and theory, and present a theoretical framework that brings into focus the multifaceted determinants of wellbeing and their interactions across multiple domains and levels of scale. We define wellbeing as positive psychological experience, promoted by connections to self, community and environment, supported by healthy vagal function, all of which are impacted by socio-contextual factors that lie beyond the control of the individual. By emphasising the factors within and beyond the control of the individual and highlighting how vagal function both affects and are impacted by key domains, the biopsychosocial underpinnings of wellbeing are explicitly linked to a broader context that is consistent with, yet complementary to, multi-levelled ecological systems theory. Reflecting on the reciprocal relationships between multiple domains, levels of scale and related social contextual factors known to impact on wellbeing, our GENIAL framework may provide a foundation for a transdisciplinary science of wellbeing that has the potential to promote the wellbeing of individuals while also playing a key role in tackling major societal challenges.

Hypofractionated Robotic Stereotactic Radiosurgery for Vagal Paragangliomas: A Novel Treatment Strategy for Cranial Nerve Preservation

Objective To provide the first description of hypofractionated stereotactic radiosurgery (SRS) and evaluate tumor control and safety for vagal paragangliomas (VPs), which begin at the skull base but often have significant extracranial extension. Study Design Retrospective chart review. Setting Tertiary-referral neurotology and neurosurgery practice. Subjects and Methods Five VPs in 4 patients (all male, ages 15-56 years) underwent SRS between 2010 and 2018. Outcome measures included tumor dimensions on serial imaging, cranial nerve function, and radiation side effects. Results CyberKnife hypofractionated SRS was performed. The prescription dose was 24 or 27 Gy (maximum dose 33.4 Gy; range, 29.3-35.5 Gy) delivered in 3 equal fractions. The mean isodose line was 79% (range, 76%-82%). Four VPs were treated primarily, and 1 tumor underwent SRS to treat regrowth 2 years after microsurgical subtotal resection via the modified infratemporal fossa approach. The treatment volume ranged from 8.81 to 86.3 cm3 (mean, 35.7 cm3). All demonstrated stable size (n = 3) or regression (n = 2) at last follow-up, 63 to 85 months after SRS (mean, 76 months). One patient had stable premorbid vocal fold paralysis from a prior ipsilateral glomus jugulare tumor resection. All others demonstrated normal vagal function following SRS. Treatment-related side effects, including dysgeusia (n = 1), mucositis (n = 1), and neck soft-tissue edema (n = 2), were self-limited. Conclusions Hypofractionated SRS appears to be both safe and effective for treating VPs, including large-volume and predominantly extracranial tumors, while preserving vagal function. SRS should be considered as a cranial nerve preservation option, especially in settings of contralateral lower cranial nerve deficits or in those with multiple paragangliomas risking both vagal nerves.

INFLUENCE OF CANCER SEVERITY AND FUNCTIONAL STATUS OF CANCER ON CARDIAC PARASYMPATHETIC INDICATORS

Objective: To investigate the influence of cancer severity and functional status of cancer patients on cardiac parasympathetic indicators. Methods: A total of 267 patients with a fresh clinical diagnosis of solid malignant tumor not yet put on cancer therapy and 250 controls matched for age, sex of study subjects were included. Severity of cancer was defined based on the American Joint Committee on Cancer staging. Accordingly, study subjects were subdivided into early stage (Stage I and II combined) and advanced stage (Stage III and IV combined). In cancer patients, the Eastern Cooperative Oncology Group (ECOG) performance score and the Faces Pain Scale score (FPS) was noted. Two indicators of vagal function, expiratory:inspiratory ratio (E:I ratio) and root mean square of successive N-N interval difference (r-MSSD) were included. E:I ratio during deep breathing at six respiratory cycles/minute and r-MSSD at rest was obtained from 1 minute lead II electrocardiogram. Data were analyzed by applying suitable statistical tests. p≤0.05 was considered significant. Results: R-MSSD and E:I ratio was significantly reduced in the early and advanced stage of cancer compared to controls (p≤0.0001). r-MSSD and E:I ratio was significantly reduced in advanced stage compared to the early stage of cancer (p≤0.0001). r-MSSD and E:I ratio was significantly different in subgroups of stages of cancer and controls (p≤0.0001). In cancer patients, r-MSSD was negatively correlated with ECOG and FPS score (p≤0.0278, p≤0.0100). Conclusion: Severity of cancer affects vagal function. However, r-MSSD alone was associated with functional status (ECOG, FPS) of cancer patients.