Interoceptive training impacts the neural circuit of the anterior insula cortex

Abstract Interoception is the perception of afferent information that arises from anywhere and everywhere within the body. Recently, interoceptive accuracy could be enhanced by cognitive training. Given that the anterior insula cortex (AIC) is a key node of interoception, we hypothesized that resting functional connectivity (RSFC) from AIC was involved in an effect of interoceptive training. To address this issue, we conducted a longitudinal intervention study using interoceptive training and obtained RSFC using fMRI before and after the intervention. A heartbeat perception task evaluated interoceptive accuracy. Twenty-two healthy volunteers (15 females, age 19.9 ± 2.0 years) participated. After the intervention, interoceptive accuracy was enhanced, and anxiety levels and somatic symptoms were reduced. Also, RSFC from AIC to the dorsolateral prefrontal cortex (DLPFC), superior marginal gyrus (SMG), anterior cingulate cortex (ACC), and brain stem, including nucleus tractus solitarius (NTS) were enhanced, and those from AIC to the visual cortex (VC) were decreased according to enhanced interoceptive accuracy. The neural circuit of AIC, ACC, and NTS is involved in the bottom-up process of interoception. The neural circuit of AIC, DLPFC, and SMG is involved in the top-down process of interoception, which was thought to represent the cognitive control of emotion. The findings provided a better understanding of neural underpinnings of the effect of interoceptive training on somatic symptoms and anxiety levels by enhancing both bottom-up and top-down processes of interoception, which has a potential contribution to the structure of psychotherapies based on the neural mechanism of psychosomatics

Proof of mechanism investigation of Transcutaneous auricular vagus nerve stimulation through simultaneous measurement of autonomic functions: a randomized controlled trial protocol

Abstract Background The autonomic nervous system plays a vital role in regulating physiological functions. Transcutaneous auricular vagus nerve stimulation (taVNS) is a method that provides insights into autonomic nerve modulation. This paper presents a research protocol investigating proof of mechanism for the impact of taVNS on autonomic functions and aims to both deepen theoretical understanding and pave the way for clinically relevant applications. Methods This protocol employs a single-blind, randomized cross-over design involving 10 healthy male participants. Simultaneous assessment of both the afferent and efferent aspects of the vagus nerve will be performed by integrating physiological measures, magnetic resonance imaging, and a questionnaire survey. Electrocardiogram will be measured to assess changes in heart rate, as a primary outcome, and heart rate variability. Active taVNS and sham stimulation will be compared, which ensures precision and blinding. Electrical stimulation will be applied to the left concha cymba and the left lobule for the active and sham conditions, respectively. The specific parameters of taVNS involve a pulse width of 250 µs, a frequency of 25 Hz, and a current adjusted to the perception threshold (0.1 mA ≤ 5 mA), delivered in cycles of 32 s on and 28 s off. Conclusions This research investigates proof of mechanism for taVNS to elucidate its modulatory effects on the central and peripheral components of the autonomic nervous system. Beyond theoretical insights, the findings will provide a foundation for designing targeted neuromodulation strategies, potentially benefiting diverse patient populations experiencing autonomic dysregulation. By elucidating the neural mechanisms, this study contributes to the evolution of personalized and effective clinical interventions in the field of neuromodulation. Trial Registration JRCT, jRCTs032220332, Registered 13 September 2022; https://jrct.niph.go.jp/latest-detail/jRCTs032220332

Usefulness of modified Pulmonary Index Score (mPIS) as a quantitative tool for the evaluation of severe acute exacerbation in asthmatic children

Background: Acute exacerbation of asthma is divided qualitatively into mild, moderate, and severe attacks and respiratory failure. This system is, however, not suitable for estimating small changes in respiratory condition with time and for determining the efficacy of treatments, because it has a qualitative, but not quantitative nature. Methods: To evaluate the usefulness of quantitative estimation of asthma exacerbation, modified Pulmonary Index Score (mPIS) values were measured in 87 asthmatic children (mean age, 5.0 ± 0.4 years) during hospitalization. mPIS was calculated by adding the sum of scores for 6 items (scores of 0–3 were given for each item). These consisted of heart rate, respiratory rate, accessory muscle use, inspiratory-to-expiratory flow ratio, degree of wheezing, and oxygen saturation in room air. Measurements were made at visits and at hospitalization and were then made twice a day until discharge. Results: mPIS values were highly correlated among raters. mPIS values at visits were 9.1 ± 0.1 and 12.6 ± 0.4 in subjects with moderate and severe attacks, respectively (p < 0.001). mPIS values of subjects requiring continuous inhalation therapy (CIT) with isoproterenol in addition to systemic steroids were significantly higher than the values of those without CIT (12.0 ± 0.5 and 9.3 ± 0.2, respectively, p < 0.001). A score of 10 was suggested to be the optimal cutoff for distinguishing between subjects requiring and not requiring CIT, from the perspectives of both sensitivity and specificity. mPIS at hospitalization correlated well with the period until discharge, suggesting that this score was a useful predictor for the clinical course after hospitalization. Conclusions: mPIS could be a useful tool for several aspects during acute asthma attacks, including the determination of a treatment plan, and prediction of the period of hospitalization in admitted patients, although prospective studies would be required to establish our hypothesis