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Duggento A, Bianciardi M, Passamonti L, Wald LL, Guerrisi M, Barbieri R, Toschi N. Globally conditioned Granger causality in brain-brain and brain-heart interactions: a combined heart rate variability/ultra-high-field (7 T) functional magnetic resonance imaging study. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2016; 374:20150185. [PMID: 27044985 PMCID: PMC4822445 DOI: 10.1098/rsta.2015.0185] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/05/2016] [Indexed: 05/24/2023]
Abstract
The causal, directed interactions between brain regions at rest (brain-brain networks) and between resting-state brain activity and autonomic nervous system (ANS) outflow (brain-heart links) have not been completely elucidated. We collected 7 T resting-state functional magnetic resonance imaging (fMRI) data with simultaneous respiration and heartbeat recordings in nine healthy volunteers to investigate (i) the causal interactions between cortical and subcortical brain regions at rest and (ii) the causal interactions between resting-state brain activity and the ANS as quantified through a probabilistic, point-process-based heartbeat model which generates dynamical estimates for sympathetic and parasympathetic activity as well as sympathovagal balance. Given the high amount of information shared between brain-derived signals, we compared the results of traditional bivariate Granger causality (GC) with a globally conditioned approach which evaluated the additional influence of each brain region on the causal target while factoring out effects concomitantly mediated by other brain regions. The bivariate approach resulted in a large number of possibly spurious causal brain-brain links, while, using the globally conditioned approach, we demonstrated the existence of significant selective causal links between cortical/subcortical brain regions and sympathetic and parasympathetic modulation as well as sympathovagal balance. In particular, we demonstrated a causal role of the amygdala, hypothalamus, brainstem and, among others, medial, middle and superior frontal gyri, superior temporal pole, paracentral lobule and cerebellar regions in modulating the so-called central autonomic network (CAN). In summary, we show that, provided proper conditioning is employed to eliminate spurious causalities, ultra-high-field functional imaging coupled with physiological signal acquisition and GC analysis is able to quantify directed brain-brain and brain-heart interactions reflecting central modulation of ANS outflow.
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Affiliation(s)
- Andrea Duggento
- Medical Physics Section, Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Rome, Italy
| | - Marta Bianciardi
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Luca Passamonti
- Istituto di Bioimmagini e Fisiologia Molecolare, Consiglio Nazionale delle Richerche, Catanzaro, Italy Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Lawrence L Wald
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Maria Guerrisi
- Medical Physics Section, Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Rome, Italy
| | - Riccardo Barbieri
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milano, Italy
| | - Nicola Toschi
- Medical Physics Section, Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Rome, Italy Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
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GUERRISI MARIA, TOSCHI NICOLA. VENTRICULAR INTERACTION AND CARDIAC PATHOLOGIES IN A THICK SHELL MODEL OF CARDIAC CHAMBER DEFORMATION. J MECH MED BIOL 2011. [DOI: 10.1142/s0219519409002821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Ventricular interdependence is an important part of heart function, and hence a key mediator of most pathological consequences of its impairment. It can only be explained by accounting for overall chamber deformation as well as cardiac dimensions and nonlinear material properties. Further, clinically useful interpretation of imaging data about pathological alterations in chamber geometry is hampered by lack of understanding of its significance in cardiac function. A model has been developed which describes the ventricles and septum as portions of ellipsoid shells, allowing structural characterization of diastolic ventricular interaction over arbitrary ranges of chamber pressures and volumes as well as intrathoracic pressures. Chamber configuration is derived as a function of pressure gradients by combining shell element equilibrium equations through static boundary conditions applied at the sulcus. Coupling coefficients between state variables are then calculated by letting the system evolve quasistatically through the solution space. The model is used to simulate a number of cardiac pathologies (constrictive pericarditis, restrictive myocarditis, left/right free wall and septal hypertrophy, left dilatative cardiomyopathy) and quantify their effect on ventricular pressure–pressure coupling as well as diastolic pressure–volume relationships. Results match experimental observations where available. The model can aid in interpreting diagnostic data about chamber geometry in a quantitative manner, and the differential effect of cardiac pathologies with otherwise similar phenomenology on ventricular interaction can serve as a discriminating diagnostic criterion.
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Affiliation(s)
- MARIA GUERRISI
- Sezione di Fisica Medica, Facoltá Di Medicina, Università Degli Studi di Roma "Tor Vergata", Rome, Italy
| | - NICOLA TOSCHI
- Sezione di Fisica Medica, Facoltá Di Medicina, Università Degli Studi di Roma "Tor Vergata", Rome, Italy
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