LF To HF Research Articles

Altered Heart Rate Variability During Mobile Game Playing and Watching Self-Mobile Gaming in Individuals with Problematic Mobile Game Use: Implications for Cardiac Health.

The surge in mobile gaming, fueled by smartphone and internet accessibility, lacks a comprehensive understanding of physiological changes during gameplay. This study, involving 93 participants (average age 21.75 years), categorized them into Problematic Mobile Gaming (PMG) and non-problematic Mobile Gaming (nPMG) groups based on Problematic Mobile Gaming Questionnaire (PMGQ) scores. The PMGQ is a 12-item scale developed in Taiwan to assess symptoms of problematic mobile gaming. The research delved into heart rate variability (HRV) alterations during real-time mobile gaming and self-gaming video viewing. Results showed that the PMG group significantly presents a lower root mean square of successive differences (RMSSD), and High Frequency (lnHF) than does the nPMG group (F=4.73, p=0.03; F=10.65, p=0.002, respectively) at the baseline. In addition, the PMG group significantly displayed elevated HF and low-frequency to high-frequency (LF/HF) in the mobile-gaming (F=7.59, p=0.007; F=9.31, p=0.003) condition as well as in the watching self-gaming videos (F=9.75, p=0.002; F=9.02, p=0.003) than did the nPMG. The study suggests targeted interventions to mitigate autonomic arousal, offering a potential avenue to address adverse effects associated with problematic mobile gaming behavior. The PMG group displayed increased craving scores after real-time mobile gaming and watching self-gaming video excerpts, unlike the nPMG group. Elevated LF/HF ratios in frequent gaming cases heightened autonomic arousal, presenting challenges in relaxation after mobile gaming. These findings contribute to a nuanced understanding of the complex interplay between mobile gaming activities, physiological responses, and potential intervention strategies.

안마의자를 활용하는 마사지가 성인 남녀의 자율신경균형도에 미치는 즉각적 영향: 전향적 관찰연구

Objectives The aim of this study was to examine the immediate impact of a massage chair intervention on homeostasis and the balance of the autonomic nervous system in individuals aged 20 to 64. Methods This study was a single-center, prospective, single-arm, investigator-initiated observational study. Non-underweight adults without significant health concerns underwent a 40-minute massage chair intervention. Measurements of heart rate variability, functional near-infrared spectroscopy, and vital signs were conducted before and after the intervention. Additionally, participants completed the Mibyeong questionnaire and a satisfaction survey. Results A 40-minute massage chair session led to a notable decrease in average heart rate and low frequency to high frequency (LF/HF) ratio, coupled with an increase in root mean square of the successive differences (RMSSD) and standard deviation of NN interval (SDNN). No adverse reactions were noted. Subjects with elevated sympathetic nerve activity exhibited a reduction in LF/HF ratio, whereas those with heightened parasympathetic activity demonstrated an increase in LF/HF ratio post-intervention. Conclusions The findings indicate that the massage chair intervention has the potential to activate the parasympathetic nervous system, promote blood pressure homeostasis and autonomic nervous system balance. However, further research over a more extended period is crucial to validate these conclusions.

Modulation of Heart Rate Variability and Brain Excitability through Acute Whole-Body Vibration: The Role of Frequency.

This cross-over study aimed to explore effects of acute whole-body vibration (WBV) at frequencies of 5-35 Hz on heart rate variability and brain excitability. Thirteen healthy physically active college students randomly completed eight interventions under the following conditions: static upright standing without vibration (CON), static squat exercise (knee flexion 150°) on the vibration platform (SSE), and static squat exercise (knee flexion 150°) combined with WBV at vibration frequency of 5, 9, 13, 20, 25, and 35 Hz. Five bouts × 30 s with a 30-s rest interval were performed for all interventions. The brain's direct current potentials (DCPs), frequency domain variables (FDV) including normalized low frequency power (nLF), normalized high frequency power (nHF) and the ratio of LF to HF (LF/HF), along with the mean heart rate (MHR) were collected and calculated before and after the WBV intervention. Results suggested that WBV frequency at 5 Hz had a substantial effect on decreasing DCPs [-2.13 μV, t(84) = -3.82, p < 0.05, g = -1.03, large] and nLF [-13%, t(84) = -2.31, p = 0.04, g = -0.62, medium]. By contrast, 20-35 Hz of acute WBV intervention considerably improved DCPs [7.58 μV, t(84) = 4.31, p < 0.05, g = 1.16, large], nLF [17%, t(84) = 2.92, p < 0.05, g = 0.79, large] and the LF/HF [0.51, t(84) = 2.86, p < 0.05, g = 0.77, large]. A strong (r = 0.7, p < 0.01) correlation between DCPs and nLF was found at 5 Hz. In summary, acute WBV at 20-35 Hz principally activated the sympathetic nervous system and increased brain excitability, while 5-Hz WBV activated the parasympathetic nervous system and reduced brain excitability. The frequency spectrum of WBV might be manipulated according to the intervention target on heart rate variability and brain excitability.

Abstract P196: The Effects of Initiating a 24-hour Fast With a Low versus a High Carbohydrate Protein Shake on Heart Rate Variability in the Elderly

Introduction: While multiple studies demonstrate the potential cardiovascular benefits of fasting, the effects of the fast-initiating meal have not been evaluated. The aim of this secondary analysis was to examine the effects of the macronutrient composition of a fast-initiating meal on the autonomic nervous system through measurements of heart rate variability (HRV) in older, sedentary adults with abdominal obesity. Methods: Using a crossover design, each of the 24 participants (13 male, 11 female) completed two 24-hour fasts (8:00 am to 8:00 am) separated by 6-10 days. Participants were 59.54 ± 6.67 years old and had a body mass index of 31.59 ± 5.59 kg/m 2 . Each fast was initiated with either a low carbohydrate protein shake or an isocaloric and isovolumetric high carbohydrate protein shake (592.13 ± 104.57 kcal). Heart rate variability was measured for 10 minutes immediately prior to, one hour after, and then 24 hours after shake consumption. Results: A mixed effects model with repeated measures was used to assess the effects of the fasting conditions on various HRV outcomes. The sympathetic (SNS) index increased significantly over the time of each fast (p = 0.0033), but was not different between conditions (p = 0.7229). The parasympathetic PNS index experienced no change over time (p = 0.1521) and no change between conditions (p = 0.8961). The stress index increased over time (p = 0.0021), but was not different between conditions (p = 0.7308). There was no difference in standard deviation of the normal-to-normal interval (SDNN) or root mean square of successive difference (RMSSD) over time (p = 0.2022 and p = 0.2770, respectively) or between condition (p = 0.9054 and p = 0.9857, respectively). The High Frequency (HF) reading was elevated in the high-carbohydrate condition compared to the low-carbohydrate condition (p &lt; 0.0001), and the low frequency to high frequency (LF/HF) ratio showed no difference between conditions (p = 0.3460), but increased over time (p = 0.0044) and demonstrated a time by condition interaction (p = 0.0089). Conclusions: Acute fasting places strain on the cardiometabolic systems as evident by the increased SNS index and stress index as well as the increase in LF/HF ratio over the course of both fasts. A low carbohydrate shake reduced HF readings, indicating more anxiety or panic in this condition. These results agree with previous works and are unique in demonstrating that most HRV parameters are neither strengthened nor weakened by the composition of the pre-fast meal.

Effect of "needle sensation" and the real-time changes in autonomic nervous system activity during acupuncture analgesia.

Acupuncture analgesia (AA) is widely used in clinical practice. The autonomic nervous system (ANS) may be an important pathway for acupuncture signal transduction. However, real-time changes in autonomic function during AA and the effect of "needle sensation" remain unclear. We established a human pain model in healthy adults and randomly assigned 128 participants to the model, sham acupuncture, and acupuncture groups in a 1:1:2 ratio. Heart rate variability (HRV), including total power (TP), low-frequency power (LF), high-frequency power (HF), ratio of LF to HF (LF/HF), standard deviation of the normal-normal intervals (SDNN), and root mean square of successive interval differences (RMSSD), were used to assess autonomic function. The visual analog scale (VAS) and efficiency were used to assess the analgesic effect of acupuncture. The Massachusetts General Hospital acupuncture sensation scale (MASS) was used to indicate the intensity of the needle sensation. Anxiety levels were also measured. Finally, the correlation of MASS with HRV, VAS, and anxiety levels was analyzed. VAS decreased after 10 min of needling and 5 min after needle withdrawal in the acupuncture group compared with those in the model group (p = 0.038, p = 0.020). The efficacy rates were 82.0, 50.0, and 61.3% in the acupuncture, model, and sham groups, respectively. These represent significant differences between the acupuncture group and the model and sham acupuncture groups (p < 0.001 in each case). No differences were observed between the model and sham acupuncture groups. HF, TP, SDNN, and RMSSD were all increased in the acupuncture group compared with those in the model group (p = 0.045, p = 0.041, p = 0.002, p = 0.006, respectively). No differences were observed in the sham acupuncture group compared to the model group (p = 0.632, p = 0.542, p = 0.093, p = 0.222, respectively). The LF and LF/HF did not differ among all three groups. A positive correlation was observed between MASS and RMSSD2, LF2, RMSSD4, TP4, VAS5, and anxiety levels. AA was associated with enhanced vagal activity. The intensity of needle sensation was positively correlated with vagal and sympathetic nerve activities. Acupuncture is an effective means of regulating autonomic function, and needle sensation may be an important modulator.

INTEGRATING HEART RATE VARIABILITY AND PSYCHOMETRIC ASSESSMENTS TO EVALUATE STRESS AND BURNOUT IN ICU NURSING STAFF: A PILOT STUDY

Background: Intensive Care Units (ICUs) are recognized as highly demanding environments that significantly contribute to stress and burnout among nursing staff. Despite increasing concern over burnout in healthcare, the relationship between physiological stress indicators, such as Heart Rate Variability (HRV), and psychometric assessments has not been thoroughly explored in this setting. Objective: This pilot study aimed to evaluate the relationship between HRV metrics and psychometric assessments of stress and anxiety in ICU nursing staff. Additionally, it explored the influence of shift type, shift duration, demographic factors, and lifestyle habits on these stress indicators. Methods: An observational cross-sectional pilot study was conducted with 24 ICU healthcare professionals at a University Hospital in Madrid, Spain. HRV data were collected under controlled conditions, with measurements taken at the beginning and end of shifts. Psychometric assessments were conducted using the State-Trait Anxiety Inventory (STAI), Perceived Stress Scale (PSS-14), Nursing Stress Scale (NSS) and a Visual Analogue Scale for Stress (VASS). Non-parametric statistical tests were used to analyze correlations between HRV metrics, psychometric scores, and demographic/lifestyle variables. Results: Significant negative correlations were observed between HRV metrics and perceived stress levels, particularly between the Low-Frequency to High-Frequency (LF/HF) ratio and stress measures. Night and extended shifts were associated with elevated stress, as indicated by lower HRV and higher psychometric stress scores. These findings suggest that shift type and duration significantly influence stress levels in ICU nursing staff. Conclusion: This pilot study highlights the potential of HRV as an objective measure of stress in ICU nursing staff, with significant correlations observed between HRV metrics and psychometric assessments. The findings suggest that HRV could be a valuable tool for monitoring stress in real time and identifying individuals at risk of burnout. However, further research with larger samples and a longitudinal approach is needed to validate these results and explore their implications for occupational health practices in ICU settings.

The Effect of Acute Hyperglycaemia Induced by Oral Glucose Load on Heart Rate Variability and Skin Microvascular Reactivity in Young Adults.

We aimed to elucidate the effects of acute hyperglycaemia, induced by an oral glucose tolerance test (OGTT), on the autonomic nervous system (ANS) and skin microvascular reactivity at the time point of peak plasma glucose concentration (cglc) in 20 young, healthy participants. We assessed their heart rate variability (HRV) as a measure of the ANS activity and the parameters of post-occlusive reactive hyperaemia (PORH) to estimate skin microvascular reactivity as measured by laser Doppler (LD) fluxmetry. The tests were repeated 30 min after a standard OGTT (75 g glucose dissolved in 250 mL water) and, in a separate control experiment, after drinking the same amount of water. Participants had their cglc and serum insulin measured at three consecutive time-points according to the testing protocol. The low-frequency (LF) spectral power, the LF to high-frequency (LF/HF) ratio, and the diastolic blood pressure increased significantly more after water than after OGTT, and there was a trend of the peak LD flux of PORH decreasing more after OGTT than after water. Significant correlations between some PORH and all the HRV parameters and cglc increase after OGTT were found, implying diminished vascular reactivity evoked by hyperglycaemia in healthy subjects with lower glucose tolerance.

Assessment of Cardiac Autonomic Function in Women With Polycystic Ovary Syndrome Through Ewing's Battery, Heart Rate Variability Analysis, and Composite Autonomic Symptom Score-31 Scale.

Introduction Polycystic ovary syndrome (PCOS) is a frequently occurringendocrine condition prevalent in women of reproductive age characterized by chronic anovulation, hyperandrogenism, insulin resistance, and a low-grade inflammatory state. Patients with PCOS are more vulnerable to developing cardiac and metabolic co-morbidities. Sympathetic overactivity is also reported in PCOS patients. Objective This study aimed to assess cardiac autonomic function in PCOS by Heart Rate Variability Analysis, Ewing's Test, and Composite Autonomic Symptom Scale-31 (COMPASS-31). Methods Thirty female PCOS patients and 30 age-matched control females were enrolled in the study. Both cases and controls were subdivided into sub-groups based on body mass index (BMI) and waist-to-hip ratio (WHR). The cardiac autonomic functions were assessed by the COMPASS-31 questionnaire, Ewing's battery tests, and short-term heart rate variability analysis. Results There was no significant difference in age, BMI, and WHR of both groups. Additionally, cases had a significantly higher low frequency to high frequency (LF/HF) ratio and COMPASS-31 score andalsoreported more derangement in Ewing's battery test, indicating cardiac autonomic dysfunction in PCOS patients. Conclusion Patients with PCOS are more prone to developing cardiac and metabolic co-morbidities.Early assessment of cardiac autonomic function can prevent future complications with timely interventions. Altered autonomic function in PCOS patients can be due to hyperandrogenism and insulin resistance.

Heart rate variability and tension-type headache: A population-based cross-sectional study

BackgroundThe relationship between tension-type headache (TTH) and autonomic functions is poorly understood, although TTH is one of the most prevalent disorders in the general population. The aim of this study was to investigate the direct and indirect effects of TTH on the autonomic functions measured by heart rate variability (HRV). MethodsThis population-based cross-sectional study was carried out in the general population of Ulaanbaatar between July and September in 2020. After physical examination, trained researchers applied structured interviews to examine the remote history of TTH and mental distress, followed by a recording of HRV to detect autonomic activity. Psychological factors and the quality of life were measured using Hospital Anxiety Depression Scale (HADS), Pittsburgh Sleep Quality Index (PSQI), and the World Health Organization Quality of Life–Brief (WHOQOL-BREF). Binary logistic regression and GLM mediation model analysis were used to examine the effects of risk factors on the associations between TTH and autonomic functions. ResultsAmong participants (n = 217, mean age=41.8 ± 11.5 years), a total of 117 (53.9%) participants had a remote history of TTH. The age and sex-adjusted prevalence was 43%. Groups did not differ statistically in the HRV indices. LF/HF (ratio of low-frequency to high frequency), the index of sympathovagal balance, was correlated with the HADS anxiety. TTH was associated with mental distress. Binary logistic regression analysis confirms the relationship suggesting that TTH was associated with increased likelihood of mental distress, and decreasing RMSSD (root mean square of the sum of the squares of differences between adjacent NN intervals) and pNN50 (NN50 divided by the total number of NN intervals) were the independent predictors of TTH. GLM mediation model indicated that the relationship between TTH and RMSSD was mediated by mental distress. ConclusionsThe present study suggests that mental distress is a critical factor in the association between TTH and autonomic dysfunction. Additionally, our findings demonstrate the influence of age and gender on TTH. These results highlight the need to understand the mechanisms underlying pathophysiology to facilitate targeted and efficacious prevention and management approaches for TTH.

Predicting sympathovagal balance using parameters of breathing patterns in abdominal breathing

Introduction. Abdominal breathing is utilized as a non-pharmacological treatment method for various stress-related conditions and autonomic dysfunctions. The objective of the study was to determine the predictors in the modulation of sympathovagal balance, as indicated by the ratio of low frequency to high frequency power of heart rate variability, by utilizing the respiratory pattern parameters recorded during the abdominal breathing model. Material and methods. The study involved a group of 101 healthy subjects, where the breathing pattern was recorded using a respiratory induction plethysmograph. Heart activity was estimated through electrocardiography, followed by heart rate variability analysis during both resting and abdominal breathing. Eight parameters of the breathing pattern were recorded in the subjects during resting breathing and abdominal breathing, presumed to be predictors of the ratio of low frequency to high frequency power of heart rate variability. Separate predictive models were created for this ratio for both the resting and abdominal breathing types. Results. The multilinear regression analysis revealed that the primary predictor with the highest predictive power for determining the balance between sympathetic and parasympathetic cardiac influence, as indicated by the low frequency spectral power to high frequency spectral power ratio, in individuals practicing abdominal breathing is Tidal Volume (unstandardized coefficient = 5.007). This was followed by the duration of expiration (coefficient = -3.831) and respiratory minute-volume (coefficient = 4.415), both of which were recorded during resting breathing. In the abdominal breathing model, the most effective predictors were found to be time-related parameters, specifically the frequency of breathing during abdominal breathing (coefficient = -5.953), the duration of the inspiratory phase (coefficient = -4.037), and the duration of the expiration phase (coefficient = -4.194). Conclusions. Abdominal breathing has the potential to normalize sympathovagal balance by adjusting the duration of inspiration or expiration. Further studies should be conducted to investigate the practical application of breathing pattern parameters in restoring the low frequency to high frequency (LF/HF) ratio, particularly in disorders characterized by elevated sympathovagal balance.

1093-P: Incretins and Cardiac Autonomic Function in Youth with Obesity across the Glycemia Spectrum

Incretins, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) have been related to vascular function with variable effects depending on obesity status in adults. The relationship of incretins to vascular function in youth is unclear. We hypothesized that endothelial and cardiac autonomic dysfunction (CAD) are related to lower GLP-1 and GIP in response to glucose ingestion in youth with dysglycemia compared with those with overweight (OW) or normal weight (NW) and normal glucose tolerance (NGT). Adolescents [50 male/52 female; 15.6±1.8 yrs; 24 NW-NGT, 22 OW-NGT, 27 prediabetes and 29 with type 2 diabetes (T2D)] underwent assessment of body composition (DXA scan), 2-hour oral glucose tolerance test (OGTT) with calculation of whole body insulin sensitivity index (WBISI), area under the curve (AUC) of glucose (BG), GLP-1 and GIP. Reactive hyperemia index (RHI), and heart rate variability (HRV), were measured by peripheral arterial tonometry. For HRV, a higher LF/HF (low frequency to high frequency ratio) is indicative of CAD with loss of parasympathetic tone and decreased HRV. The ratios of AUC-GLP-1 and AUC-GIP to AUC-BG were lower in the groups with dysglycemia compared NGT groups (p=0.016 and 0.001, respectively). GLP-1 and GIP were not related to RHI. Fasting and AUC-GLP-1, but not GIP, negatively related to LF/HF (r=-0.37, p=0.002 and r=-0.43, p&amp;lt;0.001 respectively). In a linear regression model with LnLF/HF as the dependent variable, AUC-BG (β=0.31, p=0.04) and AUC-GLP-1 (β=-0.44, p=0.002) contributed to the variance in LnLF/HF independent of %body fat, hs-CRP, WBISI, age, sex, race-ethnicity and Tanner stage (R2= 0.27, p=0.04). Youth with obesity and dysglycemia have impaired incretin response. Glycemia is negatively, whereas GLP-1 is positively associated with HRV after accounting for adiposity, WBIS and inflammation. GLP-1 may be an important determinant of CA function in youth with obesity across the glycemia spectrum. Disclosure H.El ayash: None. F.Bacha: Other Relationship; Takeda Pharmaceutical Co., Ltd., AstraZeneca. Funding U.S. Department of Agriculture-Agricultural Research Service

Effects of electroacupuncture pretreatment on GABAA receptor of fastigial nucleus and sympathetic nerve activity in rats with myocardial ischemia reperfusion injury

To observe the effects of electroacupuncture (EA) pretreatment on cardiac function, sympathetic nerve activity, indexes of myocardial injury and GABAA receptor in fastigial nucleus in rats with myocardial ischemia reperfusion injury (MIRI), and to explore the neuroregulatory mechanism of EA pretreatment in improving MIRI. A total of 60 male SD rats were randomly divided into a sham operation group, a model group, an EA group, an agonist group and an agonist+EA group, 12 rats in each group. The MIRI model was established by ligation of the left anterior descending coronary artery. EA was applied at bilateral "Shenmen" (HT 7) and "Tongli" (HT 5) in the EA group and the agonist+EA group, with continuous wave, in frequency of 2 Hz and intensity of 1 mA, 30 min each time, once a day for 7 consecutive days. After intervention, the MIRI model was established. In the agonist group, the muscone (agonist of GABAA receptor, 1 g/L) was injected in fastigial nucleus for 7 consecutive days before modeling, 150 μL each time, once a day. In the agonist+EA group, the muscone was injected in fastigial nucleus 30 min before EA intervention. The data of electrocardiogram was collected by PowerLab standard Ⅱ lead, and ST segment displacement and heart rate variability (HRV) were analyzed; the serum levels of norepinephrine (NE), creatine kinase isoenzyme MB (CK-MB) and cardiac troponin I (cTnI) were detected by ELISA; the myocardial infarction area was measured by TTC staining; the morphology of myocardial tissue was observed by HE staining; the positive expression and mRNA expression of GABAA receptor in fastigial nucleus were detected by immunohistochemistry and real-time PCR. Compared with the sham operation group, in the model group, ST segment displacement and ratio of low frequency to high frequency (LF/HF) of HRV were increased (P<0.01), HRV frequency domain analysis showed enhanced sympathetic nerve excitability, the serum levels of NE, CK-MB and cTnI were increased (P<0.01), the percentage of myocardial infarction area was increased (P<0.01), myocardial fiber was broken and interstitial edema was serious, the positive expression and mRNA expression of GABAA receptor in fastigial nucleus were increased (P<0.01). Compared with the model group, in the EA group, ST segment displacement and LF/HF ratio were decreased (P<0.01), HRV frequency domain analysis showed reduced sympathetic nerve excitability, the serum levels of NE, CK-MB and cTnI were decreased (P<0.01), the percentage of myocardial infarction area was decreased (P<0.01), myocardial fiber breakage and interstitial edema were lightened, the positive expression and mRNA expression of GABAA receptor in fastigial nucleus were decreased (P<0.01). Compared with the EA group, in the agonist group and the agonist+EA group, ST segment displacement and LF/HF ratio were increased (P<0.01), HRV frequency domain analysis showed enhanced sympathetic nerve excitability, the serum levels of NE, CK-MB and cTnI were increased (P<0.01), the percentage of myocardial infarction area was increased (P<0.01), myocardial fiber breakage and interstitial edema were aggravated, the positive expression and mRNA expression of GABAA receptor in fastigial nucleus were increased (P<0.01). EA pretreatment can improve the myocardial injury in MIRI rats, and its mechanism may be related to the inhibition of GABAA receptor expression in fastigial nucleus, thereby down-regulating the excitability of sympathetic nerve.

A Feature Fusion Method for Driving Fatigue of Shield Machine Drivers Based on Multiple Physiological Signals and Auto-Encoder

The driving fatigue state of shield machine drivers directly affects the safe operation and tunneling efficiency of shield machines during metro construction. To cope with the problem that it is challenging to simulate the working conditions and operation process of shield machine drivers using driving simulation platforms and that the existing fatigue feature fusion methods usually show low recognition accuracy, shield machine drivers at Shenyang metro line 4 in China were taken as the research subjects, and a multi-modal physiological feature fusion method based on an L2-regularized stacked auto-encoder was designed. First, the ErgoLAB cloud platform was used to extract the combined energy feature (E), the reaction time, the HRV (heart rate variability) time-domain SDNN (standard deviation of normal-to-normal intervals) index, the HRV frequency-domain LF/HF (energy ratio of low frequency to high frequency) index and the pupil diameter index from EEG (electroencephalogram) signals, skin signals, pulse signals and eye movement data, respectively. Second, the physiological signal characteristics were extracted based on the WPT (wavelet packet transform) method and time–frequency analysis. Then, a method for driving fatigue feature fusion based on an auto-encoder was designed aiming at the characteristics of the L2-regularization method to solve the over-fitting problem of small sample data sets in the process of model training. The optimal hyper-parameters of the model were verified with the experimental method of the control variable, which reduces the loss of multi-modal feature data in compression fusion and the information loss rate of the fused index. The results show that the method proposed outperforms its competitors in recognition accuracy and can effectively reduce the loss rate of deep features in existing decision-making-level fusion.

Effects of environmental control before sleeping on autonomic nervous activity and sleep: A pilot study

Sleep disorders are one of the causes that impair our quality of life, and adjustment of autonomic nervous activity can improve the sleep quality. The authors examined the effects on the sleep quality with adjustment of autonomic nervous activity by individually optimizing complex environment before sleep. Sixteen subjects underwent an environment optimization experiment during the day and subsequent sleep experiment (9 days/individual) and the ratio of low-frequency to high-frequency (LF/HF) components of heart rate variability was measured during the experiment. The LF/HF decreased under optimal conditions by 19% compared to the control conditions. Next, the effects of optimal conditions before sleep on the sleep quality were evaluated. Based on the index for the sleep quality (light sleep index), effect of the optimal environment conditions before sleep was not clearly observed for all subjects. Clustering analysis was evaluated to analyze the cause deeply. As a result, for the group of experiment subjects who did not feel nervous about the experiment, the light sleep index was decreased under optimal conditions by 29% compared to the control conditions. It was found that the effect on such stimuli could disappear in the subjects who were nervous about the experiment.

Deletion of AhR attenuates fear memory leaving other types of memory intact

The aryl hydrocarbon receptor (AhR), a classic “environmental sensor”, has been found to play an important role in cognitive and emotional function. Recent studies showed AhR deletion led to an attenuated fear memory, providing a potential target against fear memory, whether it is the consequence of attenuated sense of fear or memory ability deficit or both is unclear. Here this study aims to work this out. The freezing time in contextual fear conditioning (CFC) reduced significantly in AhR knockout mice, indicating an attenuated fear memory. Hot plate test and acoustic startle reflex showed that AhR knockout did not change the pain threshold and hearing, excluded the possibility of sensory impairments. Results from NORT, MWM and SBT showed that deletion of AhR had little effects on other types of memory. But the anxiety-like behaviors reduced both in naïve or suffered (tested after CFC) AhR knockout mice, showing that AhR-deficient mice have a reduced basal and stressful emotional response. The basal low-frequency to high-frequency (LF/HF) ratio of the AhR knockout mice was significantly lower than that of the control group, indicating lower sympathetic excitability in the basal state, suggesting a low level of basal stress in the knockout mice. Before and after CFC, the LF/HF ratio of AhR-KO mice tended to be significantly lower than that of WT mice, and their heart rate was significantly lower; and the AhR-KO mice also has a decreased serum corticosterone level after CFC, suggesting a reduced stress response in AhR knockout mice. Altogether, the basal stress level and stress response were significant reduced in AhR knockout mice, which might contribute to the attenuated fear memory with little impairment on other types of memory, suggesting AhR as a “psychologic sensor” additional to “environmental sensor”.

Association of heartbeat complexity with survival in advanced non-small cell lung cancer patients.

Previous studies have shown that the predictive value of traditional linear (time domain and frequency domain) heart rate variability (HRV) for the survival of patients with advanced non-small cell lung cancer (NSCLC) is controversial. Nonlinear methods, based on the concept of complexity, have been used to evaluate HRV, providing a new means to reveal the physiological and pathological changes in HRV. This study aimed to assess the association between heartbeat complexity and overall survival in patients with advanced NSCLC. This study included 78 patients with advanced NSCLC (mean age: 62.0 ± 9.3 years). A 5-min resting electrocardiogram of advanced NSCLC patients was collected to analyze the following HRV parameters: time domain indicators, i.e., standard deviation of the normal-normal intervals (SDNN) and root mean square of successive interval differences (RMSSD); frequency domain indicators, i.e., total power (TP), low frequency power (LF), high frequency power (HF), and the ratio of LF to HF (LF/HF); nonlinear HRV indicators characterizing heartbeat complexity, i.e., approximate entropy (ApEn), sample entropy (SampEn), and recurrence quantification analysis (RQA) indexes: mean diagonal line length (Lmean), maximal diagonal line length (Lmax), recurrence rate (REC), determinism (DET), and shannon entropy (ShanEn). Univariate analysis revealed that the linear frequency domain parameter HF and nonlinear RQA parameters Lmax, REC, and DET were significantly correlated with the survival of advanced NSCLC patients (all p < 0.05). After adjusting for confounders in the multivariate analysis, HF, REC, and DET were found to be independent prognostic factors for the survival of patients with advanced NSCLC (all p < 0.05). There was an independent association between heartbeat complexity and survival in advanced NSCLC patients. The nonlinear analysis method based on RQA may provide valuable additional information for the prognostic stratification of patients with advanced NSCLC and may supplement the traditional time domain and frequency domain analysis methods.

Combined empirical mode decomposition and phase space reconstruction based psychologically stressed and non-stressed state classification from cardiac sound signals

The psychological stress and associated mental health conditions causes high socioeconomic impacts on society and the onset of pandemic worsened the situation making it imperative to timely detect psychological stress. This paper presents a novel framework for using a combination of empirical mode decomposition (EMD) and phase space reconstruction (PSR) analysis to capture non-linear, non-stationary dynamics of cardiac sound signals acquired from fifty-four healthy male adults for detecting psychological stress. The time interval among successive S1 peaks of acquired cardiac sound signals is extracted to obtain Interbeat Interval signal used for decomposition to Intrinsic Mode Functions (IMFs) using EMD technique. Thereafter, the feature vectors namely- largest singular value, smallest singular value from two-dimensional PSRs of IMFs and the mean value of Euclidean distance, standard deviation of Euclidean distance from three-dimensional PSRs are extracted to detect psychologically stressed state. The non-parametric Kruskal-Wallis statistical test is applied to select statistically significant features that are fed to Decision Tree, Naïve Bayes and Support Vector Machine classifiers for classifying stressed and non-stressed state with fivefold cross-validation to make it a reliable system. The average accuracy, sensitivity and specificity achieved is 97.14%, 99.8% and 94% respectively using SVM and Radial Basis Function kernel function. The proposed framework performed better on the dataset in comparison to ratio of low-frequency to high-frequency (LF/HF) power parameter of Electrocardiography signal. The use of easy to acquire, cost-effective cardiac sound signals for detecting psychological stress makes proposed framework feasible for rural healthcare centres of developing economies, homecare and telemedicine.

Effect of Surya Namaskar on Autonomic Status and Serum Cortisol Levels in Male Medical Students: A Longitudinal Study

Introduction: Stress is an unavoidable and ongoing phenomenon in human life that affects physiological processes in the body. Regular practice of Surya Namaskar, a yogic exercise, has been shown to improve autonomic functions by reducing sympathetic activity, thereby decreasing stress levels and improving cortisol levels. Aim: To evaluate the effects of Surya Namaskar on autonomic status and serum cortisol levels among medical students. in the Department of Physiology at the Faculty of Medicine and Health Sciences, SGT University, Gurugram, Haryana, India. The study duration was three months, from November 2021 to January 2022. A total of 30 male medical students, aged between 18 and 21 years, were included in the study. Blood samples for cortisol estimation were collected before the start of the study and after six weeks of regular yogic practice. Parameters such as mean pulse rate, Blood Pressure (BP), and Low Frequency to High Frequency (LF/HF) ratio were also studied during these two time points. Statistical analysis of Heart Rate Variability (HRV) parameters, including Standard deviation of the N-N interval (SDNN), mean Heart Rate (HR), and pNN50, was performed using Analysis of Variance (ANOVA) at baseline and after six weeks. Comparison of serum cortisol levels within the groups was done using paired t-tests. Results: The mean age of the study participants was 20.37 years. Comparison of HRV frequency domain parameters (LF, HF, and LF/HF ratio) at baseline, day one, and after six weeks of yogic practice showed statistically significant variations in LF/ HF ratio after six weeks (p-value=0.001). Baseline serum cortisol levels compared to levels after six weeks of yogic practice were also found to be statistically significant (p&lt;0.001). Conclusion: There is a positive association between cortisol levels and autonomic parameters, as evidenced by the results of the autonomic battery of tests. Incorporating yogic interventions into one’s lifestyle helps reduce sympathetic parameters and shift the balance towards parasympathetic dominance.

Unobtrusive Cardio-Respiratory Assessment for Different Indoor Environmental Conditions

The achievement of a healthy indoor environ- ment—an indispensable requirement for human well-being—relies on the establishment of good air quality conditions and thermal comfort levels. This study addresses the development of a healthcare-focused Internet-of-Things (IoT) system for the cardiac assessment using photoplethysmography (PPG) and ballistocardiography (BCG) that can be applied in any indoor environment. Results from its experimental application include the analysis of heart rate variability (HRV) and respiratory status from a group of young adults under different thermal conditions and relative humidity (RH) levels. The final goal was to investigate the effects of short-term exposure to different air temperature and humidity conditions on human thermal comfort based on the analysis of the autonomic nervous system (ANS) activity. The experiment took place in a regular and nonisothermal office environment. Simulations based on computational fluid dynamics (CFD) were conducted to estimate heat distribution and select the optimal locations for the environmental sensor nodes’ placement. Results indicated that activation of the parasympathetic system was more notable in short-term exposures to environments with different air temperatures (24 °C–30 °C) than with different levels of RH (50%–70%). Changes in ambient air temperature led to the activation of thermal regulatory reflexes and thermal discomfort, perceived by an increase in the ratio of low frequency to high frequency (LF/HF) at higher air temperature exposures. In addition, HRV parameters were used to train machine learning models on predicting if the user is in a thermally comfortable environment or a discomfortable environment (hot or humid), having achieved an 87% average accuracy.

Autonomic nervous activity analysis based on visibility graph complex networks and skin sympathetic nerve activity.

Background: Autonomic nerve system (ANS) plays an important role in regulating cardiovascular function and cerebrovascular function. Traditional heart rate variation (HRV) and emerging skin sympathetic nerve activity (SKNA) analyses from ultra-short-time (UST) data cannot fully reveal neural activity, thereby quantitatively reflect ANS intensity. Methods: Electrocardiogram and SKNA from sixteen patients (seven cerebral hemorrhage (CH) patients and nine control group (CO) patients) were recorded using a portable device. Ten derived HRV (mean, standard deviation and root mean square difference of sinus RR intervals (NNmean, SDNN and RMSSD), ultra-low frequency (<0.003 Hz, uLF), very low frequency ([0.003 Hz, 0.04 Hz), vLF), low frequency ([0.04 Hz, 0.15 Hz), LF) and high frequency power ([0.15 Hz, 0.4 Hz), HF), ratio of LF to HF (LF/HF), the standard deviation of instantaneous beat-to-beat R-R interval variability (SD1), and approximate entropy (ApEn)) and ten visibility graph (VG) features (diameter (Dia), average node degree (aND), average shortest-path length (aSPL), clustering coefficient (CC), average closeness centrality (aCC), transitivity (Trans), average degree centrality (aDC), link density (LD), sMetric (sM) and graph energy (GE) of the constructed complex network) were compared on 5-min and UST segments to verify their validity and robustness in discriminating CH and CO under different data lengths. Besides, their potential for quantifying ANS-Load were also investigated. Results: The validation results of HRV and VG features in discriminating CH from CO showed that VG features were more clearly distinguishable between the two groups than HRV features. For effectiveness evaluation of analyzing ANS on UST segment, the NNmean, SDNN, RMSSD, LF, HF and LF/HF in HRV features and the CC, Trans, Dia and GE of VG features remained stable in both activated and inactivated segments across all data lengths. The capability of HRV and VG features in quantifying ANS-Load were evaluated and compared under different ANS-Load, the results showed that most HRV features (SDNN, LFHF, RMSSD, vLF, LF and HF) and almost all VG features were correlated to sympathetic nerve activity intensity. Conclusions: The proposed autonomic nervous activity analysis method based on VG and SKNA offers a new insight into ANS assessment in UST segments and ANS-Load quantification.