Examinando por Autor "Sclocco, Roberta"

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  • Publicación
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    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.
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    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
    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
    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.