title: Ultra-fast magnetic resonance encephalography of physiological brain activity - Glymphatic pulsation mechanisms?
abstract: The theory on the glymphatic convection mechanism of cerebrospinal fluid holds that cardiac pulsations in part pump cerebrospinal fluid from the peri-arterial spaces through the extracellular tissue into the peri-venous spaces facilitated by aquaporin water channels. Since cardiac pulses cannot be the sole mechanism of glymphatic propulsion, we searched for additional cerebrospinal fluid pulsations in the human brain with ultra-fast magnetic resonance encephalography. We detected three types of physiological mechanisms affecting cerebral cerebrospinal fluid pulsations: cardiac, respiratory, and very low frequency pulsations. The cardiac pulsations induce a negative magnetic resonance encephalography signal change in peri-arterial regions that extends centrifugally and covers the brain in ≈1 Hz cycles. The respiratory ≈0.3 Hz pulsations are centripetal periodical pulses that occur dominantly in peri-venous areas. The third type of pulsation was very low frequency (VLF 0.001-0.023 Hz) and low frequency (LF 0.023-0.73 Hz) waves that both propagate with unique spatiotemporal patterns. Our findings using critically sampled magnetic resonance encephalography open a new view into cerebral fluid dynamics. Since glymphatic system failure may precede protein accumulations in diseases such as Alzheimer's dementia, this methodological advance offers a novel approach to image brain fluid dynamics that potentially can enable early detection and intervention in neurodegenerative diseases.
authors.affiliation: Oulu Functional NeuroImaging, Department of Diagnostic Radiology, MRC, Oulu University Hospital, Oulu, Finland Medical Imaging, Physics and Technology, the Faculty of Medicine, University of Oulu, Oulu, Finland vesa.kiviniemi@oulu.fi.
authors.forename: Vesa
authors.initials: V
authors.lastname: Kiviniemi
authors.affiliation: Oulu Functional NeuroImaging, Department of Diagnostic Radiology, MRC, Oulu University Hospital, Oulu, Finland Medical Imaging, Physics and Technology, the Faculty of Medicine, University of Oulu, Oulu, Finland State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, China.
authors.forename: Xindi
authors.initials: X
authors.lastname: Wang
authors.affiliation: Oulu Functional NeuroImaging, Department of Diagnostic Radiology, MRC, Oulu University Hospital, Oulu, Finland Medical Imaging, Physics and Technology, the Faculty of Medicine, University of Oulu, Oulu, Finland.
authors.forename: Vesa
authors.initials: V
authors.lastname: Korhonen
authors.affiliation: Oulu Functional NeuroImaging, Department of Diagnostic Radiology, MRC, Oulu University Hospital, Oulu, Finland Medical Imaging, Physics and Technology, the Faculty of Medicine, University of Oulu, Oulu, Finland.
authors.forename: Tuija
authors.initials: T
authors.lastname: Keinänen
authors.affiliation: Oulu Functional NeuroImaging, Department of Diagnostic Radiology, MRC, Oulu University Hospital, Oulu, Finland Medical Imaging, Physics and Technology, the Faculty of Medicine, University of Oulu, Oulu, Finland.
authors.forename: Timo
authors.initials: T
authors.lastname: Tuovinen
authors.affiliation: Oulu Functional NeuroImaging, Department of Diagnostic Radiology, MRC, Oulu University Hospital, Oulu, Finland Functional Architecture Team, Center for Life Science Technologies, RIKEN, Japan.
authors.forename: Joonas
authors.initials: J
authors.lastname: Autio
authors.affiliation: Medical Physics, Department of Radiology, University Medical Center Freiburg, Freiburg, Germany.
authors.forename: Pierre
authors.initials: P
authors.lastname: LeVan
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, GA, USA.
authors.forename: Shella
authors.initials: S
authors.lastname: Keilholz
authors.affiliation: Center for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou, China.
authors.forename: Yu-Feng
authors.initials: YF
authors.lastname: Zang
authors.affiliation: Medical Physics, Department of Radiology, University Medical Center Freiburg, Freiburg, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hennig
authors.affiliation: School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, NY, USA.
authors.forename: Maiken
authors.initials: M
authors.lastname: Nedergaard
mesh_terms: D000328:Adult; D001921:Brain / Q000098:blood supply; D002555:Cerebrospinal Fluid / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D059906:Neuroimaging / Q000379:methods*; D011673:Pulsatile Flow / Q000502:physiology*; D055815:Young Adult
keywords: Resting state; blood oxygen level dependent; cardiorespiratory; glymphatics; magnetic resonance encephalography