Biology subjects

Candia-Rivera, D.

Publications and source records attributed to Candia-Rivera, D..

13 recordsLinked to original sources

bioRxiv2026

Brain-heart interactions predict brain activity recovery after systemic anoxia

Global cerebral anoxia is a leading cause of death and resuscitated patients often remain persistently affected by neurological deficits. While previous studies suggest that brain-heart electrophysiological interactions may predict severity and prognosis after hypoxic brain injury coma, little is known about the brain-heart dynamics at near-death. Gaining insight into these mechanisms is crucial for developing targeted interventions in critical conditions. Using a rodent model of reversible systemic anoxia (n=29, male and female rats), we investigated whether brain-heart interactions during the asphyxia onset could predict the return of brain electrical activities after resuscitation. Electrophysiological recordings confirmed that cerebral activity declines following asphyxia, coinciding with increased heart rate variability. Notably, the strong coupling between cardiac parasympathetic activity and high-frequency brain activity in the somatosensory cortex and hippocampus serves as a key predictor of a survival. Our study underscores the potential involvement of the brain-heart axis in the physiology of dying and the potential prognostic significance of the underlying mechanisms, paving the way for translational research into critical care, based on new characterizations of cardiac reflexes and brain-heart interactions. Significance StatementUnderstanding the physiological processes that determine survival and recovery following systemic anoxia is critical for improving outcomes in critical care. This study reveals that brain-heart dynamics during the onset of systemic anoxia relate to survival after resuscitation. In particular, the coupling between parasympathetic cardiac activity and high-frequency brain signals. Using a reversible anoxia rodent model, we demonstrate that early brain-heart interactions are not merely consequences of anoxia, but active markers of resilience. These findings offer a novel framework for understanding the physiology of dying and to ultimately developing prognostic tools based on real-time physiological monitoring.

neuroscience↗

bioRxiv2026

Infra-slow brain-heart-gut electrophysiological interactions reveal a coordinated multisystem physiological network in humans

Growing evidence indicates that brain continuously interacts with other physiological systems through neural and non-neural pathways. The brain-heart and brain-gut axes play a central role in homeostasis, allostasis and behaviour, but also in cognitive aspects including emotion and decision-making. Disruptions in these axes have been linked to a wide range of cardiovascular, neurological, and psychiatric disorders. Despite this evidence, triadic crosstalk between the brain, heart, and gut remains largely unexplored. Brain activity, cardiac autonomic fluctuations, and gastric rhythms all exhibit slow temporal components in resting state, suggesting that brain-heart-gut electrophysiological interactions may occur over timescales from the infra-slow (0.01-0.1 Hz) physiological range. Using non-invasive electrophysiological recordings from 28 healthy participants at rest, we extracted time-varying power dynamics describing the activity of the three organs: brain alpha power, cardiac sympathetic and parasympathetic indices, and the power of the gastric rhythm. Statistical associations among these organs were quantified using the maximal information coefficient across the extended temporal delay range. Physiological interactions were confirmed using surrogate-based testing, which allowed us to construct the network topology of interactions between the three organs. Our findings show that triadic brain-heart-gut interactions form a multi-directional network at infra-slow timescales, shaping resting state activity. This study offers one of the first insights into the physiology of brain-heart-gut interplay, providing a methodological baseline for the development of more comprehensive biomarkers based on network dynamics capable of linking pathological conditions to dysregulation across multiple organ systems. Abstract figure legend O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=90 SRC="FIGDIR/small/718683v1_ufig1.gif" ALT="Figure 1"> View larger version (20K): org.highwire.dtl.DTLVardef@6600d1org.highwire.dtl.DTLVardef@bfd404org.highwire.dtl.DTLVardef@1f85612org.highwire.dtl.DTLVardef@dac616_HPS_FORMAT_FIGEXP M_FIG C_FIG Simultaneous resting-state electroencephalographic (EEG), electrocardiographic (ECG), and electrogastrographic (EGG) recordings were processed to extract time-resolved physiological markers for each organ: EEG alpha-band power for the brain, cardiac sympathetic and parasympathetic indices (CSI, CPI) for the heart, and EGG power for the gastrointestinal tract. Coupling between time series was then quantified, and statistical significance was assessed using a surrogate-based method. Significant couplings were subsequently integrated to construct a large-scale network representation, summarizing the strength, temporal delays, and directionality of the predominant electrophysiological interactions among the three organs. Key points summaryO_LIFirst in-human, non-invasive investigation of parallel brain-heart-gut electrophysiological interactions in awake, healthy individuals. C_LIO_LIWe analysed simultaneous electroencephalographic (EEG), electrocardiographic (ECG) and electrogastrographic (EGG) recordings and quantified strength and temporal scale of the derived time-series associations, to construct a large-scale network of interactions. C_LIO_LIWe found that brain-heart-gut interactions extend into the infra-slow (0.01 - 0.1 Hz) range, indicating that spontaneous fluctuations in the electrophysiological activity of one organ at rest are typically followed by corresponding changes in the other two. C_LIO_LIWe found a consistent brain-heart-gut network topology across participants, with multidirectional interactions and bodily dynamics converging toward midline central-posterior brain regions. C_LIO_LIThese findings provide one of the first endeavours in understanding the physiology of brain-heart-gut interactions, and a methodology with strong biomarker development potential. C_LI

neuroscience↗

bioRxiv2025

Imagined movement increases the segregation of brain-heart networks

Understanding the mechanisms of motor imagery, the mental simulation of movement without execution, is key for the development of neurotechnologies, including understanding inter-individual variability in motor imagery performance. For instance, for detecting covert motor intent in noncommunicative patients or refining motor commands through brain-computer interfaces. While motor imagery engages motor-related brain regions, its precise mechanisms remain unclear, particularly in relation to cardiac dynamics. Evidence suggests heart-rate variability features have potential to enhance tasks classifications, yet the brain-heart relationship is not well understood. In this study, we examined motor imagery learning using a task involving right-hand grasping imagery. We found that motor imagery is correlated with a task-dependent modulation of cardiac sympathetic activity and its relation with directed functional connectivity from the supplementary motor area to premotor and primary motor cortices. Additionally, cerebellar-supplementary motor area segregation, in relation to cardiac parasympathetic activity, indexed longitudinal motor learning. These results suggest that dynamic reconfiguration of brain-heart interactions contributes to sensorimotor function and learning-related physiology during motor imagery, supporting the brain-heart axis as a functional component of motor imagery rather than a passive correlate.

neuroscience↗

bioRxiv2025

Cardiac-neurovascular crosstalk: Cardiac rhythms reveal maladaptive cerebral autoregulation and constrained ventilatory status

In brain-heart interactions, several pathways have been proposed to mediate feedback loops between systems. Among these, cerebrovascular dynamics operate at their interface. However, how cardiovascular control, ventilation mechanisms, and cerebral autoregulation interact is not well characterized, especially in ageing and post-stroke conditions, where perfusion can be compromised. In a cohort of 57 elderly participants, including 30 stroke survivors, we investigated the relationship between cardiac sympathetic activity and both, cerebral blood flow regulation and ventilatory status. Sympathetic reflexes, assessed via cardiac sympathetic index (CSI) during sit-to-stand transitions, were preserved across all participants, with marginal group differences between stroke and non-stroke populations. However, among individuals with constrained ventilation, indexed by reduced end-tidal CO2 at baseline, we identified a more elevated CSI following postural change, scaling with the degree of CO2 dysregulation. Furthermore, transcranial Doppler measurements revealed exaggerated changes in mean flow velocity (MFV) within the right middle cerebral artery in most participants. These MFV shifts significantly correlated with the magnitude of cardiac sympathetic change under orthostatic stress, suggesting that CSI can capture maladaptive cerebrovascular responses. Together, these findings highlight a distinct cardiac-cerebrovascular crosstalk in elderly individuals, revealing patterns consistent with compensatory or maladaptive sympathetic overactivation under conditions of impaired cerebrovascular control.

neuroscience↗

bioRxiv2024

Linking heartbeats with the cortical network dynamics involved in self-other distinction during affective touch.

Research on interoception has revealed the role of heartbeats in shaping our perceptual awareness and embodying a first-person perspective. These heartbeat dynamics exhibit distinct responses to various types of touch. We advanced that those dynamics are directly associated to the brain activity that allows self-other distinction. In our study encompassing self and social touch, we employed a method to quantify the distinct couplings of temporal patterns in cardiac sympathetic and parasympathetic activities with brain connectivity. Our findings revealed that social touch led to an increase in the coupling between frontoparietal networks and parasympathetic/vagal activity, particularly in alpha and gamma bands. Conversely, as social touch progressed, we observed a decrease in the coupling between brain networks and sympathetic dynamics across a broad frequency range. These results show how heartbeat dynamics are intertwined with brain organization and provide fresh evidence on the neurophysiological mechanisms of self-social touch distinction.

neuroscience↗

bioRxiv2024

Measuring the time-dependent effects of dobutamine on the modulations of cardiac activity in rats

Assessing cardiac dynamics over time is essential for understanding cardiovascular health and its parallel patterns of activity with the brain. We present a methodology to estimate the time-resolved sympathetic and parasympathetic modulations of cardiac dynamics, specifically tailored for the rat heart. To evaluate the performance of our method, we study a dataset comprising spontaneously hypertensive rats and Wistar-Kyoto rats. These rats were administered dobutamine to elicit autonomic dynamics. The results obtained from our method demonstrated accurate time-resolved depiction of sympathetic reactivity induced by dobutamine administration. These responses closely resembled the expected autonomic alterations observed during physical exercise conditions, albeit emulated pharmacologically. We further compared our method with standard measures of low-frequency (LF) and high-frequency (HF) components, which are commonly used, although debated, for sympathetic and parasympathetic activity estimation. The comparisons with LF and HF measures further confirmed the effectiveness of our method in better capturing autonomic changes in rat cardiac dynamics. Our findings highlight the potential of our adapted method for time-resolved analysis in future clinical and translational studies involving rodents models. The validation of our approach in animal models opens new avenues for investigating the relationship between ongoing changes in cardiac activity and parallel changes in brain dynamics. Such investigations are crucial for advancing our understanding of the brain-heart connection, particularly in cases involving neurodegeneration, brain injuries, and cardiovascular conditions. Key points- We developed a method for time-resolved estimation of sympathetic and parasympathetic modulations in rat cardiac dynamics, validated against standard LF and HF measures. - We used a cohort of spontaneously hypertensive rats and Wistar-Kyoto rats, with dobutamine administration to induce autonomic responses. - Our method accurately depicted time-resolved sympathetic reactivity similar to autonomic changes during physical exercise. - Our findings suggest potential for future clinical and translational studies on the brain-heart connection, particularly in cardiovascular conditions.

neuroscience↗

bioRxiv2024

Autonomic modulations to cardiac dynamics in response to affective touch: Differences between social touch and self-touch

The autonomic nervous system plays a vital role in self-regulation and responding to environmental demands. Autonomic dynamics have been hypothesized to be involved in perceptual awareness and the physiological implementation of the first-person perspective. Based on this idea, we hypothesized that the autonomic activity measured from cardiac dynamics could differentiate between social touch and self-touch. In our study, we used a newly developed method to analyze the temporal dynamics of cardiac sympathetic and parasympathetic activities during an ecologically valid affective touch experiment. We revealed that different types of touch conditions--social-touch, self-touch, and a control object-touch--resulted in a decrease in sympathetic activity. This decrease was more pronounced during social touch, as compared to the other conditions. Following sympathetic decrease, we quantified an increase in parasympathetic activity specifically during social touch, further distinguishing it from self-touch. Importantly, by combining the sympathetic and parasympathetic indices, we successfully differentiated social touch from the other experimental conditions, indicating that social touch exhibited the most substantial changes in cardiac autonomic indices. These findings may have important clinical implications as they provide insights into the neurophysiology of touch, relevant for aberrant affective touch processing in specific psychiatric disorders and for the comprehension of nociceptive touch.

neuroscience↗

bioRxiv2023

Robust and time-resolved estimation of cardiac sympathetic and parasympathetic indices

The time-resolved analysis of heart rate (HR) and heart rate variability (HRV) is crucial for the evaluation of the dynamic changes of autonomic activity under different clinical and behavioral conditions. Standard HRV analysis is performed in the frequency domain because the sympathetic activations tend to increase low-frequency HRV oscillations, while the parasympathetic ones increase high-frequency HRV oscillations. However, a strict separation of HRV in frequency bands may cause biased estimations, especially in the low frequency range. To overcome this limitation, we propose a robust estimator that combines HR and HRV dynamics, based on the correlation of the Poincare plot descriptors of interbeat intervals from the electrocardiogram. To validate our method, we used electrocardiograms gathered from open databases where standardized paradigms were applied to elicit changes in autonomic activity. Our proposal outperforms the standard spectral approach for the estimation of low- and high-frequency fluctuations in HRV, and its performance is comparable to newer methods. Our method constitutes a valuable, robust, time-resolved, and cost-effective tool for a better understanding of autonomic activity through HR and HRV in healthy state and potentially for pathological conditions.

neuroscience↗

bioRxiv2023

The entropic heart: Tracking the psychedelic state via heart rate dynamics

A growing body of work shows that autonomic signals provide a privileged evidence-stream to capture various aspects of subjective and neural states. This work investigates the potential for autonomic markers to track the effects of psychedelics -- potent psychoactive drugs with important scientific and clinical value. For this purpose, we introduce a novel Bayesian framework to estimate the entropy of heart rate dynamics under psychedelics. We also calculate Bayesian estimates of mean heart rate and heart rate variability, and investigate how these measures relate to subjective reports and neural effects. Results on datasets covering four drugs -- lysergic acid diethylamide (LSD), dimethyltryptamine (DMT), psilocybin, and sub-anaesthetic doses of the dissociative agent ketamine -- show consistent increases in mean heart rate, high-frequency heart rate variability, and heart rate entropy during the psychedelic experience. Moreover, these effects have predictive power over various dimensions of the psychedelic experience. Changes in heart rate entropy were found to be correlated with increases in brain entropy, while other autonomic markers were not. Overall, our results show that a cost-efficient autonomic measure has the potential to reveal surprising detail about subjective and brain states, opening up a range of new research avenues to explore in both basic and clinical neuroscience.

physiology↗

bioRxiv2022

Dynamic fluctuations in ascending heart-to-brain modulations under mental stress elicitation

Dynamical information exchange between central and autonomic nervous systems, as referred to functional brain-heart interplay, occurs during emotional and physical arousal. It is well documented that physical and mental stress lead to sympathetic activation. Nevertheless, the role of autonomic inputs in nervous-system-wise communication under mental stress is yet unknown. In this study, we estimated the causal and bidirectional neural modulations between EEG oscillations and peripheral sympathetic and parasympathetic activities using a recently proposed computational framework for a functional brain-heart interplay assessment, namely the sympathovagal synthetic data generation model. Mental stress was elicited in 37 healthy volunteers by increasing their cognitive demands throughout three tasks associated with increased stress levels. Stress elicitation induced an increased variability in sympathovagal markers, as well as increased variability in the directional brain-heart interplay. The observed heart-to-brain interplay was primarily from sympathetic activity targeting a wide range of EEG oscillations, whereas variability in the efferent direction seemed mainly related to EEG oscillations in the gamma band. These findings extend current knowledge on stress physiology, which mainly referred to top-down neural dynamics. Our results suggest that mental stress may not cause an increase in sympathetic activity exclusively as it initiates a dynamic fluctuation within brain-body networks including bidirectional interactions at a brain-heart level. We conclude that directional brain-heart interplay measurements may provide suitable biomarkers for a quantitative stress assessment and bodily feedback may modulate the perceived stress caused by increased cognitive demand.

neuroscience↗

bioRxiv2022

Nonlinear Neural Patterns Are Revealed In High Frequency fNIRS Analysis

Vasomotor tone has a direct implication in oxygen transport to neural tissue, and its dynamics are known to be under constant control from feedback loops with visceral signals, such as sympathovagal interactions. Functional Near Infrared Spectroscopy (fNIRS) offers a nuanced measure of hemoglobin concentration that also comprises high frequencies, though most fNIRS literature studies traditional frequency ranges of hemodynamics (< 0.2 Hz). Linear theory of the hemodynamic response function supports this low frequency band, but we hypothesize that nonlinear effects elicited from the complex system sustaining vasomotor tone presents itself in higher frequencies. To characterize these effects, we investigate how plausible modulation of autoregulatory effects impact aforementioned high frequency components of fNIRS through simulations of mechanistic hemodynamic models. Then, we compare representational similarities between fast (0.2 Hz to 0.6 Hz) and slow (< 0.2 Hz) wave fNIRS to demonstrate that representations acquired through nonlinear analysis are distinct between the frequency bands, whereas when using linear time-domain analysis they are not. Furthermore, by comparing topoplots of significant detectors using nonlinear random vector correlation methods (distance correlation), we demonstrate through a 2nd level group analysis that the median concentrations acquired by fNIRS are independent when analyzing the nonlinearity of their dynamics in their fast and slow component, while they are dependent when utilizing linear time-domain analysis. This study not only provides motivation for researchers to also include higher frequency components in their analysis, but also provides motivation to explore nonlinear effects, e.g. topological entropy. The results of this study motivate future research to explore the nonlinear autoregulatory impacts of regional blood flow and hemoglobin concentrations. Author summaryConventionally, hemodynamic response from induced neural metabolic demand is studied as a slow signal, i.e < 0.2 Hz. Though this may be justified in linear analysis of hemodynamics, vascular mechanics nonlinearly transform the neural metabolic demand to hemodynamic response, where a nonlinear spectral profile may show higher frequency responses. Higher frequency ranges may give insight into local vascular dynamics, particularly their reflection of autoregulatory phenomena, hypothesized to be controlled by sympathovagal feedback loops, thus opening a new avenue for studying brain-body interactions. Functional near infrared spectroscopy (fNIRS) offers a method with high temporal resolution (10 Hz) for observing these effects in hemoglobin concentrations. In this study, we utilize stochastic dynamical simulations of plausible autoregulatory phenomena and an open fNIRS dataset to study differences of fast and slow wave neurovascular representations. We demonstrate that, while linear time-domain analysis provides similar representations of fast and slow wave activity, representations derived from nonlinear methods are not. Furthermore, we show how stress tasks, which may elicit autonomic activity, further desynchronizes nonlinear activity between fast and slow wave signals compared to a non-stress inducing task, demonstrating unique high frequency neurovascular phenomena that is mediated by stress processing.

neuroscience↗

bioRxiv2022

Effects of neural monitoring and control of visceral signals on heart rate, respiration rate, and frontal hemodynamics

Recent studies have established that cardiac and respiratory phases can modulate perception and related neural dynamics. While heart rate and respiratory sinus arrhythmia possibly affect interoception biomarkers, such as heartbeat-evoked potentials, the relative changes in heart rate and cardiorespiratory dynamics in interoceptive processes have not yet been investigated. In this study, we investigated the variation in heart and breathing rates, as well as higher functional dynamics including cardiorespiratory correlation and frontal hemodynamics measured with fNIRS, during a heartbeat counting task. To further investigate the functional physiology linked to changes in vagal activity caused by specific breathing rates, we performed the heartbeat counting task together with a controlled breathing rate task. The results demonstrate that focusing on heartbeats decreases breathing and heart rates in comparison, which may be part of the physiological mechanisms related to "listening" to the heart, the focus of attention, and self-awareness. Focusing on heartbeats was also observed to increase frontal connectivity, supporting the role of frontal structures in the neural monitoring of visceral inputs. However, cardiorespiratory correlation is affected by both heartbeats counting and controlled breathing tasks. Based on these results, we concluded that variations in heart and breathing rates are confounding factors in the assessment of interoceptive abilities and relative fluctuations in breathing and heart rates should be considered to be a mode of covariate measurement of interoceptive processes.

neuroscience↗

bioRxiv2021

Cardiac sympathovagal activity initiates a functional brain-body response to emotional processing

A century-long debate on bodily states and emotions persists. While the involvement of bodily activity in emotion physiology is widely recognized, the specificity and causal role of such activity related to brain dynamics has not yet been demonstrated. We hypothesize that the peripheral neural monitoring and control of cardiovascular activity prompts and sustains brain dynamics during an emotional experience, so these afferent inputs are processed by the brain by triggering a concurrent efferent information transfer to the body. To this end, we investigated the functional brain-heart interplay under emotion elicitation in publicly available data from 62 healthy participants using a computational model based on synthetic data generation of EEG and ECG signals. Our findings show that sympathovagal activity plays a leading and causal role in initiating the emotional response, in which ascending modulations from vagal activity precede neural dynamics and correlate to the reported level of arousal. The subsequent dynamic interplay observed between the central and autonomic nervous systems sustains emotional processing. These findings should be particularly revealing for the psychophysiology and neuroscience of emotions. SignificanceWe investigate the temporal dynamics of brain and cardiac activities in healthy subjects who underwent an emotional elicitation through videos. We demonstrate that, within the first few seconds, emotional stimuli modulate the heart activity, which in turn stimulate an emotion-specific cortical response in the brain. Then, the conscious emotional experience is sustained by a bidirectional brain-heart interplay and information exchange. Moreover, the perceived intensity of an emotional stimulus is predicted by the intensity of neural control regulating the heart activity. These findings may constitute the fundamental knowledge linking neurophysiology and psychiatric disorders, including the link between depressive symptoms and cardiovascular disorders.

neuroscience↗