title: Magnetic vestibular stimulation modulates default mode network fluctuations.
abstract: Strong magnetic fields (>1 Tesla) can cause dizziness and it was recently shown that healthy subjects (resting in total darkness) developed a persistent nystagmus even when remaining completely motionless within a MR tomograph. Consequently, it was speculated that this magnetic vestibular stimulation (MVS) might influence fMRI results, as nystagmus is indicative of an imbalance in the vestibular system, potentially influencing other systems via multisensory vestibular interactions. The objective of our study was to investigate whether MVS does indeed modulate BOLD signal fluctuations. We recorded eye movements, as well as, resting-state fMRI of 30 volunteers in darkness at 1.5 T and 3.0 T to answer the question whether MVS modulated parts of the default mode resting-state network (DMN) in accordance with the Lorentz-force model for MVS, while distinguishing this from the known signal increase due to field strength related imaging effects. Our results showed that modulation of the default mode network occurred mainly in areas associated with vestibular and ocular motor function, and was in accordance with the Lorentz-force model, i.e., double than the expected signal scaling due to field strength alone. We discuss the implications of our findings for the interpretation of studies using resting-state fMRI, especially those concerning vestibular research. We conclude that MVS needs to be considered in vestibular research to avoid biased results, but it might also offer the possibility of manipulating network dynamics and may thus help in studying the brain as a dynamical system.
authors.affiliation: German Center for Vertigo and Balance Disorders (DSGZ-IFB(LMU)), Ludwig-Maximilians-University Munich, Germany; Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University Munich, Germany. Electronic address: Rainer.Boegle@googlemail.com.
authors.forename: Rainer
authors.initials: R
authors.lastname: Boegle
authors.affiliation: German Center for Vertigo and Balance Disorders (DSGZ-IFB(LMU)), Ludwig-Maximilians-University Munich, Germany; Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University Munich, Germany; Department of Neurology, Ludwig-Maximilians-University Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Stephan
authors.affiliation: Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University Munich, Germany; Department of Neurology, Ludwig-Maximilians-University Munich, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Ertl
authors.affiliation: German Center for Vertigo and Balance Disorders (DSGZ-IFB(LMU)), Ludwig-Maximilians-University Munich, Germany; Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University Munich, Germany; Center for Sensorimotor Research, Ludwig-Maximilians-University Munich, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Glasauer
authors.affiliation: German Center for Vertigo and Balance Disorders (DSGZ-IFB(LMU)), Ludwig-Maximilians-University Munich, Germany; Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University Munich, Germany; Department of Neurology, Ludwig-Maximilians-University Munich, Germany; SyNergy: Cluster for Systems Neurology, Munich, Germany.
authors.forename: Marianne
authors.initials: M
authors.lastname: Dieterich
mesh_terms: D001921:Brain / Q000502:physiology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D060526:Magnetic Fields / Q000009:adverse effects*; D008279:Magnetic Resonance Imaging / Q000009:adverse effects*; D008297:Male; D009759:Nystagmus, Pathologic / Q000175:diagnosis; D009760:Nystagmus, Physiologic; D014722:Vestibule, Labyrinth / Q000503:physiopathology
keywords: Magnetic vestibular stimulation; Resting-state fMRI; Resting-state networks; Vestibular imbalance