Examinando por Autor "Barbieri, Riccardo"

Mostrando 1 - 9 de 9
  • Publicación
    Acceso abierto
    Brain Circuitry Supporting Multi-Organ Autonomic Outflow in Response to Nausea
    (2016-02) García, Ronald G.; Kim, Jieun; Sheehan, James D.; Beissner, Florian; Bianchi, Anna M.; Cerutti, Sergio; Kuo, Braden; Barbieri, Riccardo; Napadow, Vitaly; Sclocco, Roberta
    While autonomic outflow is an important co-factor of nausea physiology, central control of this outflow is poorly understood. We evaluated sympathetic (skin conductance level) and cardiovagal (high-frequency heart rate variability) modulation, collected synchronously with functional MRI (fMRI) data during nauseogenic visual stimulation aimed to induce vection in susceptible individuals. Autonomic data guided analysis of neuroimaging data, using a stimulus-based (analysis windows set by visual stimulation protocol) and percept-based (windows set by subjects’ ratings) approach. Increased sympathetic and decreased parasympathetic modulation was associated with robust and anti-correlated brain activity in response to nausea. Specifically, greater autonomic response was associated with reduced fMRI signal in brain regions such as the insula, suggesting an inhibitory relationship with premotor brainstem nuclei. Interestingly, some sympathetic/parasympathetic specificity was noted. Activity in default mode network and visual motion areas was anti-correlated with parasympathetic outflow at peak nausea. In contrast, lateral prefrontal cortical activity was anticorrelated with sympathetic outflow during recovery, soon after cessation of nauseogenic stimulation. These results suggest divergent central autonomic control for sympathetic and parasympathetic response to nausea. Autonomic outflow and the central autonomic network underlying ANS response to nausea may be an important determinant of overall nausea intensity and, ultimately, a potential therapeutic target.
  • Publicación
    Acceso abierto
    Complexity Variability Assessment of Nonlinear Time-Varying Cardiovascular Control
    (2017-02-20) García, Ronald G.; Citi, Luca; NoggleTaylor, Jessica; Toschi, Nicola; Barbieri, Riccardo; Valenza, Gaetano
    The application of complex systems theory to physiology and medicine has provided meaningful information about the nonlinear aspects underlying the dynamics of a wide range of biological processes and their disease-related aberrations. However, no studies have investigated whether meaningful information can be extracted by quantifying second-order moments of time-varying cardiovascular complexity. To this extent, we introduce a novel mathematical framework termed complexity variability, in which the variance of instantaneous Lyapunov spectra estimated over time serves as a reference quantifier. We apply the proposed methodology to four exemplary studies involving disorders which stem from cardiology, neurology and psychiatry: Congestive Heart Failure (CHF), Major Depression Disorder (MDD), Parkinson’s Disease (PD), and Post-Traumatic Stress Disorder (PTSD) patients with insomnia under a yoga training regime. We show that complexity assessments derived from simple time-averaging are not able to discern pathology-related changes in autonomic control, and we demonstrate that between-group differences in measures of complexity variability are consistent across pathologies. Pathological states such as CHF, MDD, and PD are associated with an increased complexity variability when compared to healthy controls, whereas wellbeing derived from yoga in PTSD is associated with lower time-variance of complexity.
  • Publicación
    Acceso abierto
    Dose-Optimization of Respiratory-Gated Auricular Vagal Afferent Nerve Stimulation (RAVANS) for Blood Pressure Modulation in Hypertensive Patients
    (2019-09-05) Stowell, Jessica; Garcia, Ronald G.; Staley, Rachel; Sclocco, Roberta; Fisher, Harrison; Napadow, Vitaly; Goldstein, Jill; Barbieri, Riccardo
    The objective of this study was to determine the optimal frequency of respiratory-gated auricular vagal afferent nerve stimulation (RAVANS) for the modulation of blood pressure in hypertensive patients. Twelve hypertensive subjects (52.5±6.0 years, 8 females) underwent five randomized stimulation sessions, during which they received exhalatory-gated stimulation at frequencies of 2, 10, 25, and 100 Hz or sham stimulation. A continuous blood pressure signal was collected during a 30-minute stimulation period and a 10-minute recovery period using a Finometer device (Finapress Medical System, the Netherlands). LabChart (ADInstruments, Colorado Springs, CO, USA) was used to process and compute blood pressure responses. A significantly greater reduction of systolic blood pressure values during stimulation was observed in the 100 Hz session compared to sham (p=0.02). In addition, significant reductions in diastolic blood pressure (p=0.04) and mean arterial pressure (p=0.04) values were observed during RAVANS stimulation compared to baseline during the 100 Hz session. Evaluation of other stimulation frequencies did not reveal significant results. RAVANS exhibits a frequency-dependent effect on the modulation of arterial blood pressure levels of hypertensive subjects.
  • Publicación
    Acceso abierto
    Neuroimaging brainstem circuitry supporting cardiovagal response to pain : A combined heart rate variability/ultrahigh-field (7 T) functional magnetic resonance imaging study
    (2016-01) García, Ronald G.; Sclocco, Roberta; Beissner, Florian; Desbordes, Gaelle; Polimeni, Jonathan R.; Wald, Lawrence L.; Kettner, Norman W.; Kim, Jieun; Renvall, Ville; Bianchi, Anna M.; Cerutti, Sergio; Napadow, Vitaly; Barbieri, Riccardo
    Central autonomic control nuclei in the brainstem have been difficult to evaluate non-invasively in humans. We applied ultrahigh-field (7 T) functional magnetic resonance imaging (fMRI), and the improved spatial resolution it affords (1.2 mm isotropic), to evaluate putative brainstem nuclei that control and/or sense pain-evoked cardiovagal modulation (high-frequency heart rate variability (HF-HRV) instantaneously estimated through a point-process approach). The time-variant HF-HRV signal was used to guide the general linear model analysis of neuroimaging data. Sustained (6 min) pain stimulation reduced cardiovagal modulation, with the most prominent reduction evident in the first 2 min. Brainstem nuclei associated with pain-evoked HF-HRV reduction were previously implicated in both autonomic regulation and pain processing. Specifically, clusters consistent with the rostral ventromedial medulla, ventral nucleus reticularis (Rt)/nucleus ambiguus (NAmb) and pontine nuclei (Pn) were found when contrasting sustained pain versus rest. Analysis of the initial 2-min period identified Rt/NAmb and Pn, in addition to clusters consistent with the dorsal motor nucleus of the vagus/nucleus of the solitary tract and locus coeruleus. Combining high spatial resolution fMRI and high temporal resolution HF-HRV allowed for a non-invasive characterization of brainstem nuclei, suggesting that nociceptive afference induces pain-processing brainstem nuclei to function in concert with known premotor autonomic nuclei in order to affect the cardiovagal response to pain.
  • Publicación
    Acceso abierto
    Nonlinear digital signal processing in mental health : Characterization of major depression using instantaneous entropy measures of heartbeat dynamics
    (2015-03-13) Valenza, Gaetano; García, Ronald G.; Citi, Luca; Scilingo, Enzo P.; Tomaz, Carlos A.; Barbieri, Riccardo
    Nonlinear digital signal processing methods that address system complexity have provided useful computational tools for helping in the diagnosis and treatment of a wide range of pathologies. More specifically, nonlinear measures have been successful this study, we propose the use of instantaneous measures of entropy, namely the inhomogeneous point-process approximate entropy (ipApEn) and the inhomogeneous point-process sample entropy (ipSampEn), to describe a novel characterization of MD patients undergoing affective elicitation. Because these measures are built within a nonlinear point-process model, they allow for the assessment of complexity in cardiovascular dynamics at each moment in time. Heartbeat dynamics were characterized from 48 healthy controls and 48 patients with MD while emotionally elicited through either neutral or arousing audiovisual stimuli. Experimental results coming from the arousing tasks show that ipApEn measures are able to instantaneously track heartbeat complexity as well as discern between healthy subjects and MD patients. Conversely, standard heart rate variability (HRV) analysis performed in both time and frequency domains did not show any statistical significance. We conclude that measures of entropy based on non linear point-process models might contribute to devising useful computational tools for care in mental health
  • Publicación
    Acceso abierto
    Relationship between cardiac vagal activity and mood congruent memory bias in major depression
    (2016-01) García, Ronald G.; Valenza, Gaetano; Tomaz, Carlos A.; Barbieri, Riccardo
    Background Previous studies suggest that autonomic reactivity during encoding of emotional information could modulate the neural processes mediating mood-congruent memory. In this study, we use a point-process model to determine dynamic autonomic tone in response to negative emotions and its influence on long-term memory of major depressed subjects. Methods Forty-eight patients with major depression and 48 healthy controls were randomly assigned to either neutral or emotionally arousing audiovisual stimuli. An adaptive point-process algorithm was applied to compute instantaneous estimates of the spectral components of heart rate variability [Low frequency (LF), 0.04–0.15 Hz; High frequency (HF), 0.15–0.4 Hz]. Three days later subjects were submitted to a recall test. Results A significant increase in HF power was observed in depressed subjects in response to the emotionally arousing stimulus (p=0.03). The results of a multivariate analysis revealed that the HF power during the emotional segment of the stimulus was independently associated with the score of the recall test in depressed subjects, after adjusting for age, gender and educational level (Coef. 0.003, 95%CI, 0.0009–0.005, p=0.008). Limitations These results could only be interpreted as responses to elicitation of specific negative emotions, the relationship between HF changes and encoding/recall of positive stimuli should be further examined. Conclusions Alterations on parasympathetic response to emotion are involved in the mood-congruent cognitive bias observed in major depression. These findings are clinically relevant because it could constitute the mechanism by which depressed patients maintain maladaptive patterns of negative information processing that trigger and sustain depressed mood.
  • Publicación
    Acceso abierto
    Respiratory-gated Auricular Vagal Afferent Nerve Stimulation (RAVANS) effects on autonomic outflow in hypertension
    (2017-09-05) Sclocco, Roberta; Garcia, Ronald G.; Gabriel, Aileen; Kettner, Norman W.; Napadow, Vitaly; Barbieri, Riccardo
    Transcutaneous stimulation of the auricular branch of the vagus nerve (ABVN) has been proposed as a non-invasive alternative to vagus nerve stimulation (VNS). However, its cardiovagal effects are inconsistent across studies, likely due to inhomogeneity in the stimulation parameters. Here, we evaluate respiratory-gated ABVN stimulation (Respiratory-gated Auricular Vagal Afferent Nerve Stimulation, RAVANS), where the stimuli are delivered in 1 s bursts during the exhalation phase of respiration, thus mimicking the breathing-induced modulation of cardiac vagal activity. In this study, we present preliminary results from an ongoing single-arm, open label trial investigating the effects of different intensities of RAVANS in hypertensive subjects. We found that a mid-intensity RAVANS stimulation (rated as a 5 on a 0-10 scale) increases the cardiovagal tone and reduces the sympathetic tone during a paced breathing task. The present results could contribute to optimize RAVANS as a non-invasive, low-cost therapeutic intervention for hypertension.
  • Publicación
    Acceso abierto
    The somatosensory link in fibromyalgia
    (2015-05) Kim, Jieun; Loggia, Marco L.; Cahalan, Christine M.; Harris, Richard E.; Beissner, Florian; García, Ronald G.; Kim, Hyungjun; Barbieri, Riccardo; Wasan, Ajay D.; Edwards, Robert R.; Napadow, Vitaly
    Objective.Fibromyalgia (FM) is a chronic func-tional pain syndrome characterized by widespread pain,significant pain catastrophizing, sympathovagal dysfunc-tion, and amplified temporal summation for evoked pain.While several studies have demonstrated altered restingbrain connectivity in FM, studies have not specificallyprobed the somatosensory system and its role in bothsomatic and nonsomatic FM symptoms. Our objective wasto evaluate resting primary somatosensory cortex (S1) con-nectivity and to explore how sustained, evoked deep tissuepain modulates this connectivity.Methods.We acquired functional magnetic reso-nance imaging and electrocardiography data on FMpatients and healthy controls during rest (the rest phase)and during sustained mechanical pressure–induced painover the lower leg (the pain phase). Functional connectiv-ity associated with different S1 subregions was calculated,while S1legconnectivity (representation of the leg in theprimary somatosensory cortex) was contrasted betweenthe rest phase and the pain phase and was correlated withclinically relevant measures in FM.Results.During the rest phase, FM patientsshowed decreased connectivity between multiple ipsilat-eral and cross-hemispheric S1 subregions, which wascorrelated with clinical pain severity. Compared to therest phase, the pain phase produced increased S1legconnectivity to the bilateral anterior insula in FMpatients, but not in healthy controls. Moreover, in FMpatients, sustained pain–altered S1legconnectivity tothe anterior insula was correlated with clinical/behavioral pain measures and autonomic responses.Conclusion.Our study demonstrates that bothsomatic and nonsomatic dysfunction in FM, includingclinical pain, pain catastrophizing, autonomic dysfunction,and amplified temporal summation, are closely linkedwith the degree to which evoked deep tissue pain alters S1 connectivity to salience/affective pain-processing regions. Additionally, diminished connectivity between S1 subregions during the rest phase in FM may result from ongoing widespread clinical pain.
  • Publicación
    Acceso abierto
    Stimulus frequency modulates brainstem response to respiratory-gated transcutaneous auricular vagus nerve stimulation
    (2020-03-27) Sclocco, Roberta; Garcia, Ronald G.; Kettner, Norman W.; Fisher, Harrison P.; Isenburg, Kylie; Makarovsky, Maya; Stowell, Jessica A.; Goldstein, Jill; Barbieri, Riccardo; Napadow, Vitaly; Neurociencias
    Background: The therapeutic potential of transcutaneous auricular VNS (taVNS) is currently being explored for numerous clinical applications. However, optimized response for different clinical indications may depend on specific neuromodulation parameters, and systematic assessments of their influence are still needed to optimize this promising approach. Hypothesis: We proposed that stimulation frequency would have a significant effect on nucleus tractus solitarii (NTS) functional MRI (fMRI) response to respiratory-gated taVNS (RAVANS). Methods: Brainstem fMRI response to auricular RAVANS (cymba conchae) was assessed for four different stimulation frequencies (2, 10, 25, 100 Hz). Sham (no current) stimulation was used to control for respiration effects on fMRI signal. Results: Our findings demonstrated that RAVANS delivered at 100 Hz evoked the strongest brainstem response, localized to a cluster in the left (ipsilateral) medulla and consistent with purported NTS. A colocalized, although weaker, response was found for 2 Hz RAVANS. Furthermore, RAVANS delivered at 100 Hz also evoked stronger fMRI responses for important monoamine neurotransmitter source nuclei (LC, noradrenergic; MR, DR, serotonergic) and pain/homeostatic regulation nuclei (i.e. PAG). Conclusion: Our fMRI results support previous localization of taVNS afference to pontomedullary aspect of NTS in the human brainstem, and demonstrate the significant influence of the stimulation frequency on brainstem fMRI response.