title: Effects of astrocytic dynamics on spatiotemporal hemodynamics: Modeling and enhanced data analysis.
abstract: The effects of astrocytic dynamics on the blood oxygen-level dependent (BOLD) response are modeled. The dynamics are represented via an astrocytic response function that approximates the effects of astrocytic activity, including delay between neural activity and hemodynamic response. The astrocytic response function is incorporated into a spatiotemporal hemodynamic model to predict the BOLD response measured using functional magnetic resonance imaging (fMRI). Adding astrocytic dynamics is shown to significantly improve the ability of the model to robustly reproduce the spatiotemporal properties of the experimental data such as characteristic frequency and time-to-peak. Moreover, the results are consistent across different astrocytic response functions, thus a simple impulsive form suffices to model the effective time delay of astrocytic responses. Finally, the results yield improved estimates of previously reported hemodynamic parameters, such as natural frequency and decay rate of the flow signal, which are consistent with experimentally verified physiological limits. The techniques developed in this study will contribute to improved analysis of BOLD-fMRI data.
authors.affiliation: School of Physics, University of Sydney, New South Wales 2006, Australia; Center for Integrative Brain Function, University of Sydney, New South Wales 2006, Australia. Electronic address: james.pang@sydney.edu.au.
authors.forename: J C
authors.initials: JC
authors.lastname: Pang
authors.affiliation: School of Physics, University of Sydney, New South Wales 2006, Australia; Center for Integrative Brain Function, University of Sydney, New South Wales 2006, Australia.
authors.forename: P A
authors.initials: PA
authors.lastname: Robinson
authors.affiliation: School of Physics, University of Sydney, New South Wales 2006, Australia; Sir Peter Mansfield Imaging Center, School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom.
authors.forename: K M
authors.initials: KM
authors.lastname: Aquino
authors.affiliation: School of Physics, University of Sydney, New South Wales 2006, Australia; Sydney Medical School, University of Sydney, New South Wales 2006, Australia.
authors.forename: N
authors.initials: N
authors.lastname: Vasan
mesh_terms: D000328:Adult; D001253:Astrocytes / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D059907:Functional Neuroimaging / Q000379:methods*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008959:Models, Neurological; D014796:Visual Perception / Q000502:physiology
keywords: Astrocyte; BOLD; Hemodynamics; Modeling; Prediction; fMRI