Human Autonomic Nervous System Research Articles

Analysis of cardiovascular function in diabetic patients using EEMD-ICA fusion multi-scale percussion entropy.

Diabetes is a chronic disease that can lead to a variety of complications and even cause death. The signal characteristics of the photoplethysmography signals (PPG) and electrocardiogram signals (ECG) can reflect the autonomic and vascular aspects of the effects of diabetes on the body. Based on the complex mechanism of interaction between PPG and ECG, a set of ensemble empirical mode decomposition-independent component analysis (EEMD-ICA) fusion multi-scale percussion entropy index (MSPEI) method was proposed to analyze cardiovascular function in diabetic patients. Firstly, the original signal was decomposed into multiple Intrinsic Mode Function (IMFs) by ensemble empirical mode decomposition EEMD, principal components of IMF were extracted by independent component analysis (ICA), then the extracted principal components were reconstructed to eliminate the complex high and low frequency noise of physiological signals. In addition, the MSPEI was calculated for the ECG R-R interval and PPG amplitude sequence.(RRI and Amp) The results showed that, compared with EEMD method, the SNR of EEMD-ICA method increases from 2.1551 to 11.3642, and the root mean square error (RMSE) decreases from 0.0556 to 0.0067. This algorithm can improve the performance of denoising and retain more feature information. The large and small scale entropy of MSPEI (RRI,Amp) was significantly different between healthy and diabetic patients (p< 0.01). Compared with arteriosclerosis index (AI) and multi-scale cross-approximate entropy (MCAE): MSPEISS (RRI,Amp) indicated that diabetes can affect the activity of human autonomic nervous system, while MSPEILS (RRI,Amp) indicated that diabetes can cause or worsen arteriosclerosis. Multi-scale Percussion Entropy algorithm has more advantages in analyzing the influence of diabetes on human cardiovascular and autonomic nervous function.

Assessing the Anxiolytic and Relaxation Effects of Cinnamomum camphora Essential Oil in University Students: A Comparative Study of EEG, Physiological Measures, and Psychological Responses.

Cinnamomum camphora is a commercially important tree species in China, and it's also a common native tree in the forests of southern China. However, literature on the impact of Cinnamomum camphora essential oil (CCEO) on human psychophysiological activity is scarce. Hence, the primary objective of this study was to examine the effect of exposure to CCEO on the functioning of the human autonomic nervous system, electroencephalographic (EEG) activity, and emotional state. Forty-three healthy university students participated. The data collected included heart rate (HR), blood pressure (BP), pulse rate, blood oxygen saturation (SpO2), electroencephalographic (EEG) activity, and the results of the Profile of Mood States (POMS) test. A drop in diastolic pressure (DBP) and pulse rate was also noticed after participants inhaled CCEO. Furthermore, EEG studies have demonstrated notable reductions in absolute beta (AB), absolute gamma (AG), absolute high beta (AHB), and relative gamma (RG) power spectra during exposure to CCEO. Conversely, the relative theta (RT) and power spectra values showed a significant increase. Additionally, the finding from POMS indicated that the fragrance evoked positive emotions and suppressed negative feelings. The results suggest that exposure to CCEO may promote mental and physical relaxation, facilitate cognitive processes such as memory and attention, and enhance mood states.

A Literature Review on Anxiety of the Athletes' Performance

In this era of modernization, performance is one of the stress factors that often trigger affective reactions of anxiety, as well as psychophysiological changes in the human autonomic nervous system. In the context of sports performance assessment, athletes experience high levels of anxiety which often have a negative influence on their performance as anxiety tend to be a typical phenomenon experienced by athletes across various sports disciplines. Anxiety can be understood as a negative affective variable associated with a low level of performance (Gómez‐Íñiguez, Rodríguez, &amp; Cantero, 2021). Present study applied narrative review on the previous studies as the research method to examine the factors and effects of the anxiety on the athletes’ performance. By synthesizing the findings from multiple previous studies, this study also aims to provide a deeper understanding of anxiety in athletes' performance and offer insights for future researchers and all other parties who involved in sports. Present study concluded that internal factors are the crucial elements that contribute to the anxiety on the athletes’ performance, and anxiety level tend to be able to increase or decrease the athletes’ performance. In order to ensure the positive effects of anxiety, athletes have to aware and stay in their optimal intensity zone for them to maximize their performance. More research, interventions and application of technology in anxiety awareness and management are recommended for the future researchers.

Cardiac psychophysiological tuning to socioaffective content is disrupted in aged rhesus monkeys (Macaca mulatta).

Aging ushers in numerous disruptions to autonomic nervous system (ANS) function. Although the effects of aging on ANS function at rest are well characterized, there is surprising variation in reports of age-related differences in ANS reactivity to psychosocial stressors, with some reports of decreases and other reports of increases in reactivity with age. The sources of variation in age-related differences are largely unknown. Nonhuman primate models of socioaffective aging may help to uncover sources of this variation as nonhuman primates share key features of human ANS structure and function and researchers have precise control over the environments in which they age. In this report, we assess how response patterns to dynamic socioaffective stimuli in the parasympathetic and sympathetic branches of rhesus monkeys (Macaca mulatta) ANS differ in aged compared to middle-aged monkeys. We find that respiratory sinus arrhythmia, a cardiac indicator of activity in the parasympathetic branch of the ANS, exhibits age-related disruptions in responding while monkeys view videos of conspecifics. This suggests that there are evolutionarily conserved mechanisms responsible for the patterns of affective aging observed in humans and that aged rhesus monkeys are a robust translational model for human affective aging.

A systematic review of HRV during diving in very cold water

ABSTRACT Heart rate variability (HRV) is a useful method to study the autonomic nervous system (ANS) status. As measuring devices have developed and become smaller, many researchers have become interested in the possibilities to implement the method for diving medicine research. The aim of this study was to review human ANS responses in cold water diving (water temperature <5°C), and to comprise the current knowledge of HRV studies in diving and hyperbaric exposure into one review article. A literature search was conducted on 5 Decemberth 2022, with the search terms “HRV” or “heart rate variability” and “diving” or “diver” or “divers”, with search functions of the data bases PubMed and Ovid Medline. Peer reviewed original articles, review articles and case reports were accepted to this review. Twenty-six articles met the pre-defined criteria and were included in this review. Studies from very cold water conditions were rare, but suggested that cold strengthens the ANS responses of diving – especially parasympathetic nervous system (PNS) activity due to the trigeminocardiac reflex and baroreceptor and cardiac stretch receptor activity, caused cold and pressure-induced centralisation of the blood. Overall, studies showed predominant PNS activity when putting the face in water, during immersion and when ambient pressure increased.

DESIGNING OF HEALTH-SAVING MEN’S GLOVES

Living during a COVID-19 pandemic has negative effects on a person's psychophysiological state such as high-stress levels, leading to poor health, chronic fatigue and insomnia. As a result, the immunity is reduced, which is particularly dangerous today. One way to solve this problem is the use of health-saving clothing, which has additional features that provide the positive effect on the wearer’s body. The developed gloves affect the state of the human autonomic nervous system through biological-active locations in the places of the hand and wrist. An anthropometric study of the biological-active locations of the wrist and hand is performed to construct the glove design. An algorithm for constructing a drawing of the design of the designed product based on four measurements is proposed. The effectiveness of the adaptive gloves is confirmed by studying its effect on the psycho-emotional and psychophysiological state of a person without exposure to the product and after its use by software "Intera-Diacor" and "ROFES", and a questionnaire. The evaluation is performed after wearing gloves for 20-40 minutes. It was found that 83.3 % of the wearers of the health-saving gloves showed positive changes in the body's compensatory forces (stress) and the state of internal emotional fatigue. Thus, the use of health-saving gloves has a positive social, therapeutic (health-saving) and economic effect, as the product has several functions It is an accessory fashion, has hand protection, and, has additional features to positively influence the body of the person wearing it. This allows the future to talk about the use of consumer-friendly and effective ways to correct the men's psychoemotional and psychophysiological states, based on the safer-by-design concept.

Non-contact neuromodulation of the human autonomic nervous system function via different odors: Sex, menstrual cycle, and odor dose- and duration-specific effects.

In recent decades, it has been uncovered that the autonomic nervous system (ANS) can be influenced using non-contact neuromodulation via odor stimulation. Increasing parasympathetic-vagal activation of the ANS is integral to improving the sympathovagal balance between the sympathetic- and parasympathetic nervous systems, which is often imbalanced in several chronic inflammatory disorders, such as rheumatoid arthritis and inflammatory bowel diseases. Although research into olfactory stimulation has been observed on the ANS, it is still lacking in the exploration of odor concentration and odor-specific effects. This is particularly the case as research has not utilized specified tools, such as the olfactometer to provide precise odor delivery. Furthermore, no research has compared the results in separate sex cohorts to investigate the role of sex or the menstrual stage on the subsequent interactions. In this study, we investigated the olfactory stimulation effects of four natural odors (mushroom, lavender, jasmine, and rose) in three concentrations (low, moderate, and high) on the ANS. To observe activity from the ANS, we used an electrocardiogram (ECG) based heart rate variability (HRV) and eye-tracker technology (pupil diameter). We found for the first time in literature that there were acute dose- and duration-specific odor effects of odors on the ANS. We also found sex and menstrual cycle effects in this interaction. Furthermore, there were stark distinctions in sympathovagal activity dependent ANS activation (HRV) in comparison to the oculomotor nerve-parasympathetic/cervical sympathetic nerves dependent ANS responses (pupil diameter). Sympathovagal activity dependent HRV showed odor, sex, and menstrual-stage interactions in both divisions of the ANS while the pupil responses only indicated increased sympathetic activation. These results shed light on the use of odor-specific stimulation to modulate the ANS activity in the context of sex and the menstrual stage. Future studies should be performed using a chronic odor delivery design to investigate the long-term effects of odors on the ANS.Clinical trial registrationAustralian New Zealand Clinical Trials Registry, identifier [ACTRN12622000415707].

The omnipresence of autonomic modulation in health and disease.

The Autonomic Nervous System (ANS) is a critical part of the homeostatic machinery with both central and peripheral components. However, little is known about the integration of these components and their joint role in the maintenance of health and in allostatic derailments leading to somatic and/or neuropsychiatric (co)morbidity. Based on a comprehensive literature search on the ANS neuroanatomy we dissect the complex integration of the ANS: (1) First we summarize Stress and Homeostatic Equilibrium - elucidating the responsivity of the ANS to stressors; (2) Second we describe the overall process of how the ANS is involved in Adaptation and Maladaptation to Stress; (3) In the third section the ANS is hierarchically partitioned into the peripheral/spinal, brainstem, subcortical and cortical components of the nervous system. We utilize this anatomical basis to define a model of autonomic integration. (4) Finally, we deploy the model to describe human ANS involvement in (a) Hypofunctional and (b) Hyperfunctional states providing examples in the healthy state and in clinical conditions.

Longitudinal Changes and Recovery in Heart Rate Variability of Young Healthy Subjects When Exposure to a Hypobaric Hypoxic Environment.

Background: The autonomic nervous system (ANS) is crucial for acclimatization. Investigating the responses of acute exposure to a hypoxic environment may provide some knowledge of the cardiopulmonary system’s adjustment mechanism.Objective: The present study investigates the longitudinal changes and recovery in heart rate variability (HRV) in a young healthy population when exposed to a simulated plateau environment.Methods: The study followed a strict experimental paradigm in which physiological signals were collected from 33 healthy college students (26 ± 2 years, 171 cm ± 7 cm, 64 ± 11 kg) using a medical-grade wearable device. The subjects were asked to sit in normoxic (approximately 101 kPa) and hypoxic (4,000 m above sea level, about 62 kPa) environments. The whole experimental process was divided into four stable resting measurement segments in chronological order to analyze the longitudinal changes of physical stress and recovery phases. Seventy-six time-domain, frequency-domain, and non-linear indicators characterizing rhythm variability were analyzed in the four groups.Results: Compared to normobaric normoxia, participants in hypobaric hypoxia had significantly lower HRV time-domain metrics, such as RMSSD, MeanNN, and MedianNN (p < 0.01), substantially higher frequency domain metrics such as LF/HF ratio (p < 0.05), significantly lower Poincaré plot parameters such as SD1/SD2 ratio and other Poincaré plot parameters are reduced considerably (p < 0.01), and Refined Composite Multi-Scale Entropy (RCMSE) curves are reduced significantly (p < 0.01).Conclusion: The present study shows that elevated heart rates, sympathetic activation, and reduced overall complexity were observed in healthy subjects exposed to a hypobaric and hypoxic environment. Moreover, the results indicated that Multiscale Entropy (MSE) analysis of RR interval series could characterize the degree of minor physiological changes. This novel index of HRV can better explain changes in the human ANS.

Toward a Real-Time Index of Pupillary Activity as an Indicator of Cognitive Load

The Low/High Index of Pupillary Activity (LHIPA), an eye-tracked measure of pupil diameter oscillation, is redesigned and implemented to function in real-time. The novel Real-time IPA (RIPA) is shown to discriminate cognitive load in re-streamed data from earlier experiments. Rationale for the RIPA is tied to the functioning of the human autonomic nervous system yielding a hybrid measure based on the ratio of Low/High frequencies of pupil oscillation. The paper's contribution is drawn from provision of documentation of the calculation of the RIPA. As with the LHIPA, it is possible for researchers to apply this metric to their own experiments where a measure of cognitive load is of interest.

Inter-Brain Synchrony Levels According to Task Execution Modes and Difficulty Levels: An fNIRS/GSR Study.

Hyperscanning is a brain imaging technique that measures brain synchrony caused by social interactions. Recent research on hyperscanning has revealed substantial inter-brain synchrony (IBS), but little is known about the link between IBS and mental workload. To study this link, we conducted an experiment consisting of button-pressing tasks of three different difficulty levels for the cooperation and competition modes with 56 participants aged 23.7± 3.8 years (mean±standard deviation). We attempted to observe IBS using functional near-infrared spectroscopy (fNIRS) and galvanic skin response (GSR) to assess the activities of the human autonomic nervous system. We found that the IBS levels increased in a frequency band of 0.075-0.15 Hz, which was unrelated to the task repetition frequency in the cooperation mode according to the task difficulty level. Significant relative inter-brain synchrony (RIBS) increases were observed in three and 10 channels out of 15 for the hard tasks compared to the normal and easy tasks, respectively. We observed that the average GSR values increased with increasing task difficulty levels for the competition mode only. Thus, our results suggest that the IBS revealed by fNIRS and GSR is not related to the hemodynamic changes induced by mental workload, simple behavioral synchrony such as button-pressing timing, or autonomic nervous system activity. IBS is thus explicitly caused by social interactions such as cooperation.

LSD and ketanserin and their impact on the human autonomic nervous system.

The interest in lysergic acid diethylamide (LSD) has sparked again due to its supposed positive effects on psychopathological conditions. Yet, most research focuses on the actions of LSD on the central nervous system. The interaction with the autonomic nervous system (ANS) has been neglected so far. Therefore, the aim was to assess the effects of LSD and the serotonin 2A receptor antagonist ketanserin on the ANS as assessed by heart rate variability (HRV) measures and their correlation with subjective drug-induced effects in a randomized, placebo-controlled crossover trial. Thus, ANS activity was derived from electrocardiogram recordings after intake of placebo, LSD or ketanserin, and LSD by calculating R-peak-based measures of sympathetic and parasympathetic activity. Repeated measure ANOVA and partial correlation for HRV measures and subjective experience questionnaires were performed. LSD predominantly increased sympathetic activity, while ketanserin counteracted this effect on the ANS via an increase of parasympathetic tone. Sympathetic activity was positively and parasympathetic activity negatively associated with psychedelic effects of LSD. Furthermore, Placebo HRV measures predicted subjective experiences after LSD intake. The association between trait ANS activity and LSD-induced subjective experiences may serve as a candidate biomarker set for the effectiveness of LSD in the treatment of psychopathological conditions.

Global Study of Human Heart Rhythm Synchronization with the Earth’s Time Varying Magnetic Field

Changes in geomagnetic conditions have been shown to affect the rhythms produced by the brain and heart and that human autonomic nervous system activity reflected in heart rate variability (HRV) over longer time periods can synchronize to changes in the amplitude of resonant frequencies produced by geomagnetic field-line and Schumann resonances. During a 15-day period, 104 participants located in California, Lithuania, Saudi Arabia, New Zealand, and England underwent continuous ambulatory HRV monitoring. The local time varying magnetic field (LMF) intensity was obtained using a time synchronized and calibrated network of magnetometers located at five monitoring sites in the same geographical locations as the participant groups. This paper focuses on the results of an experiment conducted within the larger study where all of the participants simultaneously did a heart-focused meditation called a Heart Lock-In (HLI) for a 15-min period. The participant’s level of HRV coherence and HRV synchronization to each other before, during and after the HLI and the synchronization between participants’ HRV and local time varying magnetic field power during each 24-h period were computed for each participant and group with near-optimal chaotic attractor embedding techniques. In analysis of the participants HRV coherence before, during and after the HLI, most of the groups showed significantly increased coherence during the HLI period. The pairwise heart rhythm synchronization between participants’ in each group was assessed by determining the Euclidean distance of the optimal time lag vectors of each participant to all other participants in their group. The group member’s heart rhythms were significantly more synchronized with each other during the HLI period in all the groups. The participants’ daily LMF-HRV-synchronization was calculated for each day over an 11-day period, which provided a 5-day period before, the day of and 5-days after the HLI day. The only day where all the groups HRV was positively correlated with the LMF was on the day of the HLI and the synchronization between the HRV and LMF for all the groups was significantly higher than most of the other days.

Pupil dilation reflects the authenticity of received nonverbal vocalizations

The ability to infer the authenticity of other’s emotional expressions is a social cognitive process taking place in all human interactions. Although the neurocognitive correlates of authenticity recognition have been probed, its potential recruitment of the peripheral autonomic nervous system is not known. In this work, we asked participants to rate the authenticity of authentic and acted laughs and cries, while simultaneously recording their pupil size, taken as proxy of cognitive effort and arousal. We report, for the first time, that acted laughs elicited higher pupil dilation than authentic ones and, reversely, authentic cries elicited higher pupil dilation than acted ones. We tentatively suggest the lack of authenticity in others’ laughs elicits increased pupil dilation through demanding higher cognitive effort; and that, reversely, authenticity in cries increases pupil dilation, through eliciting higher emotional arousal. We also show authentic vocalizations and laughs (i.e. main effects of authenticity and emotion) to be perceived as more authentic, arousing and contagious than acted vocalizations and cries, respectively. In conclusion, we show new evidence that the recognition of emotional authenticity can be manifested at the level of the autonomic nervous system in humans. Notwithstanding, given its novelty, further independent research is warranted to ascertain its psychological meaning.

Content adaptation neural network method cause-specific the state of users

The aim of the study is to develop recommendations for adapting educational content based on the use of a neural network method for recognizing the human autonomic nervous system degree of activity. The initial data for decision making are the vectors of cardiointervals obtained with the help of the pulse sensor. The state of the autonomic nervous system is monitored by a two-layer artificial neural network of direct propagation. The artificial neural network was trained by combining gradient and stochastic training methods. A trial sample was used as a training set, consisting of 168 records of people’s cardiointervals belonging to different social and age groups. The presented method for recognizing the autonomic nervous system activity degree was tested via the shared programming support environment Lazarus. As a result of network training, a set of weighting coefficient values was found, for which 100% correct recognition is performed over the entire trial sample. A personalized training system that monitors the functional state of the student varies the presentation of educational content. When the functional state changes during the training load, the virtual agent organizes the training process so as to avoid stress load.

Identification of healthy and pathological heartbeat dynamics based on ECG-waveform using multifractal spectrum

Human body surface electrocardiogram (ECG) is non-stationary and frequency-varying by nature that belongs to a typical nonlinear signal. Therefore, traditional linear and time–frequency​ analysis methods cannot fully disclose its nonlinear nature. Meanwhile, physiological complexity of heartbeat signal may vary with age, diseases, drug administrations, or even behavioral modifiers. To test the intrinsic relationships among them, we first put forward a theoretical model for nonlinear time series analysis and then took the generally accepted multifractal sets to verify it. Upon that, we then investigated the multifractal singularity spectrum areas of synchronous 12-lead ECG signals taken from crowds with different age stages, healthy conditions and drug medications. Our results suggested that aging and diseases can not only decrease multifractal complexity of the signals, but also increase inhomogeneity of it. With aging and deepening lesion, fractal-like structure of the heartbeat system is damaged or even structurally changed, which lead to the declination of physiological complexity and at the same time the increasement of irregularity and anisotropy of ECG signal’s propagation. In addition, the mean value of multifractal spectrum area of human 12-lead ECG signals also reflect the self-discipline regulation of human autonomic nervous system. The value descends with age growing or drug intervention to restrain sympathetic nerves. That suggest self-discipline control function weakens when people are getting old, or they are under repressed heartbeat activities with lower heart rate and lower blood pressure. Then, complexity of heartbeat signal declines and even tends to turn from multifractality to monofractality, which means drops off of human individual adaptability.

Significance of electrodermal activity response in children with autism spectrum disorder

&lt;span&gt;The human Autonomic Nervous System (ANS) controls the body’s physiological responses such as heart rate, electrodermal activity, temperature, and pupil diameter. The physiological responses are increased in the presence of a stressing stimuli and this is a typical ANS response. However, in case of children with Autism Spectrum Disorder (ASD), &lt;/span&gt;&lt;span&gt;they suffer from autonomic dysregulation as reported in past owing to their atypical ANS response. This study investigated the ANS response of children with ASD and compares it with the response of normal children. &lt;/span&gt;&lt;span&gt;EDA response datasets of 35 children with ASD and 55 normal children were acquired with the help of E4 wristband at a sampling rate of 4Hz. &lt;/span&gt;&lt;span&gt;The signals were preprocessed to remove artefacts and noise and later compared. Furthermore, an SVM classifier was also used to classify the EDA response signals of normal children and children with ASD. The obtained results highlight that the ANS response of children with ASD is atypical as their EDA response is blunt and shows no significant tonic and phasic changes in EDA levels in the presence of stressing stimuli. In addition to that, an accuracy of 75% was obtained using the LF kernel of SVM classifier. The study further unfolds the hypoactive sympathetic response of children with ASD during a stressing event. Furthermore, this will help in future to anticipate the emotional responses of children with ASD such as anger, happiness, and anxiety.&lt;/span&gt;

Oxygen-Detecting Synaptic Device for Realization of Artificial Autonomic Nervous System for Maintaining Oxygen Homeostasis.

Incorporation of various functions of a biological nervous system into electronic devices is an intriguing challenge in the realization of a human-like recognition and response system. Emerging artificial synaptic devices capable of processing electronic signals through neuromorphic functions operate such biomimetic systems similarly to biological nervous systems. Here, an oxygen-sensitive artificial synaptic device that simultaneously detects oxygen concentration and generates a synaptic signal is demonstrated. The device successfully achieves an interconversion between the excitatory and inhibitory modes of the synaptic current at various oxygen concentrations by virtue of an oxygen-sensitive trilayered organic double heterojunction. The oxygen-induced traps in the organic layer modulate the majority charge carrier from holes to electrons, and this modulation induces an interconversion between the excitatory and inhibitory modes according to the environmental oxygen condition. Finally, the proposed synaptic device is applied to the realization of a negative feedback system for regulation of oxygen homeostasis, which mimics the human autonomic nervous system. The oxygen-sensitive synaptic device proposed in this study is expected to open up new possibilities for the development of a biomimetic neural system that can respond appropriately to various environmental changes.

Studying the Effect of Bengali Folk Music on Human Autonomic Nervous System Through Multi-Fractal Detrended Fluctuation Analysis of HRV Signals

Music therapy is a frequently used tool to treat cardiac and neurological diseases. It has been proven that music impacts human body as well as mind. The reason behind such impact of music on humans is because of the release of a chemical agent inside the brain known as dopamine also known as the happy hormone. Autonomic Nervous System (ANS) is reactive to the chemical stimuli which comprises of sympathetic and parasympathetic nerves. In this paper, we present the effect of Bengali folk music on ANS. The signals were taken while the subject is listening to music and also during normal resting condition. In time series analysis, multifractal detrended fluctuation analysis (MF-DFA) is used for determining the statistical self-affinity and highly chaotic behavior of a signal. Multifractal detrended fluctuation analysis is used as a quantifying parameter to detect the effect of Bengali folk music on ANS. Our experimental result shows a satisfactory result in this context.

Concomitant Evaluation of Heart Period and QT Interval Variability Spectral Markers to Typify Cardiac Control in Humans and Rats.

The variability of heart period, measured as the time distance between two consecutive QRS complexes from the electrocardiogram (RR), was exploited to infer cardiac vagal control, while the variability of the duration of the electrical activity of the heart, measured as the time interval from Q-wave onset to T-wave end (QT), was proposed as an indirect index of cardiac sympathetic modulation. This study tests the utility of the concomitant evaluation of RR variability (RRV) and QT variability (QTV) markers in typifying cardiac autonomic control of humans under different experimental conditions and of rat groups featuring documented differences in resting sympatho-vagal balance. We considered: (i) 23 healthy young subjects in resting supine position (REST) undergoing head-up tilt at 45° (T45) and 90° (T90) followed by recovery to the supine position; (ii) 9 Wistar (WI) and 14 wild-type Groningen (WT) rats in unstressed conditions, where the WT animals were classified as non-aggressive (non-AGG, n = 9) and aggressive (AGG, n = 5) according to the resident intruder test. In humans, spectral analysis of RRV and QTV was performed over a single stationary sequence of 250 consecutive values. In rats, spectral analysis was iterated over 10-min recordings with a frame length of 250 beats with 80% overlap and the median of the distribution of the spectral markers was extracted. Over RRV and QTV we computed the power in the low frequency (LF, from 0.04 to 0.15 Hz in humans and from 0.2 to 0.75 Hz in rats) band (LFRR and LFQT) and the power in the high frequency (HF, from 0.15 to 0.5 Hz in humans and from 0.75 to 2.5 Hz in rats) band (HFRR and HFQT). In humans the HFRR power was lower during T90 and higher during recovery compared to REST, while the LFQT power was higher during T90. In rats the HFRR power was lower in WT rats compared to WI rats and the LFQT power was higher in AGG than in non-AGG animals. We concluded that RRV and QTV provide complementary information in describing the functioning of vagal and sympathetic limbs of the autonomic nervous system in humans and rats.