title: Age-related decline in functional connectivity of the vestibular cortical network.
abstract: In the elderly, major complaints include dizziness and an increasing number of falls, possibly related to an altered processing of vestibular sensory input. In this study, we therefore investigate age-related changes induced by processing of vestibular sensory stimulation. While previous functional imaging studies of healthy aging have investigated brain function during task performance or at rest, we used galvanic vestibular stimulation during functional MRI in a task-free sensory stimulation paradigm to study the effect of healthy aging on central vestibular processing, which might only become apparent during stimulation processing. Since aging may affect signatures of brain function beyond the BOLD-signal amplitude-such as functional connectivity or temporal signal variability--we employed independent component analysis and partial least squares analysis of temporal signal variability. We tested for age-associated changes unrelated to vestibular processing, using a motor paradigm, voxel-based morphometry and diffusion tensor imaging. This allows us to control for general age-related modifications, possibly originating from vascular, atrophic or structural connectivity changes. Age-correlated decreases of functional connectivity and increases of BOLD--signal variability were associated with multisensory vestibular networks. In contrast, no age-related functional connectivity changes were detected in somatosensory networks or during the motor paradigm. The functional connectivity decrease was not due to structural changes but to a decrease in response amplitude. In synopsis, our data suggest that both the age-dependent functional connectivity decrease and the variability increase may be due to deteriorating reciprocal cortico-cortical inhibition with age and related to multimodal vestibular integration of sensory inputs.
authors.affiliation: Department of Neurology, Ludwig-Maximilians-University Munich, Marchioninistr. 15, 81377, Munich, Germany. carolin.cyran.14@ucl.ac.uk.|Institute of Neurology, University College London, Queen Square, London, WCN1 3BG, UK. carolin.cyran.14@ucl.ac.uk.
authors.forename: Carolin Anna Maria
authors.initials: CA
authors.lastname: Cyran
authors.affiliation: Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University Munich, Marchioninistr. 15, 81377, Munich, Germany.|German Center for Vertigo and Balance Disorders, (IFBLMU), Ludwig-Maximilians-University Munich, Marchioninistr. 15, 81377, Munich, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Boegle
authors.affiliation: Department of Neurology, Ludwig-Maximilians-University Munich, Marchioninistr. 15, 81377, Munich, Germany.|Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University Munich, Marchioninistr. 15, 81377, Munich, Germany.|German Center for Vertigo and Balance Disorders, (IFBLMU), Ludwig-Maximilians-University Munich, Marchioninistr. 15, 81377, Munich, Germany.|Institute for Clinical Neurosciences, Ludwig-Maximilians-University Munich, Marchioninistr. 15, 81377, Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Stephan
authors.affiliation: Department of Neurology, Ludwig-Maximilians-University Munich, Marchioninistr. 15, 81377, Munich, Germany.|Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University Munich, Marchioninistr. 15, 81377, Munich, Germany.|German Center for Vertigo and Balance Disorders, (IFBLMU), Ludwig-Maximilians-University Munich, Marchioninistr. 15, 81377, Munich, Germany.|SyNergy: Cluster for Systems Neurology, Munich, Germany.
authors.forename: Marianne
authors.initials: M
authors.lastname: Dieterich
authors.affiliation: Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University Munich, Marchioninistr. 15, 81377, Munich, Germany.|German Center for Vertigo and Balance Disorders, (IFBLMU), Ludwig-Maximilians-University Munich, Marchioninistr. 15, 81377, Munich, Germany.|Center for Sensorimotor Research, Ludwig-Maximilians-University Munich, Marchioninistr. 15, 81377, Munich, Germany.|Institute for Clinical Neurosciences, Ludwig-Maximilians-University Munich, Marchioninistr. 15, 81377, Munich, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Glasauer
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods; D056324:Diffusion Tensor Imaging; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D009434:Neural Pathways / Q000502:physiology; D014724:Vestibular Function Tests; D014722:Vestibule, Labyrinth / Q000502:physiology*; D055815:Young Adult
keywords: Aging; Functional connectivity; Independent component analysis; Temporal BOLD-signal variability; Vestibular; fMRI