title: fMRI hemodynamics accurately reflects neuronal timing in the human brain measured by MEG.
abstract: Neuronal activation sequence information is essential for understanding brain functions. Extracting such timing information from blood oxygenation level dependent (BOLD) fMRI is confounded by interregional neurovascular differences and poorly understood relations between BOLD and electrophysiological response delays. Here, we recorded whole-head BOLD fMRI at 100 ms resolution and magnetoencephalography (MEG) during a visuomotor reaction-time task. Both methods detected the same activation sequence across five regions, from visual towards motor cortices, with linearly correlated interregional BOLD and MEG response delays. The smallest significant interregional BOLD delay was 100 ms; all delays ≥400 ms were significant. Switching the order of external events reversed the sequence of BOLD activations, indicating that interregional neurovascular differences did not confound the results. This may open new avenues for using fMRI to follow rapid activation sequences in the brain.
authors.affiliation: Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan. fhlin@ntu.edu.tw
authors.forename: Fa-Hsuan
authors.initials: FH
authors.lastname: Lin
authors.forename: Thomas
authors.initials: T
authors.lastname: Witzel
authors.forename: Tommi
authors.initials: T
authors.lastname: Raij
authors.forename: Jyrki
authors.initials: J
authors.lastname: Ahveninen
authors.forename: Kevin Wen-Kai
authors.initials: KW
authors.lastname: Tsai
authors.forename: Yin-Hua
authors.initials: YH
authors.lastname: Chu
authors.forename: Wei-Tang
authors.initials: WT
authors.lastname: Chang
authors.forename: Aapo
authors.initials: A
authors.lastname: Nummenmaa
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Polimeni
authors.forename: Wen-Jui
authors.initials: WJ
authors.lastname: Kuo
authors.forename: Jen-Chuen
authors.initials: JC
authors.lastname: Hsieh
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Rosen
authors.forename: John W
authors.initials: JW
authors.lastname: Belliveau
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D009474:Neurons / Q000502:physiology*; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology*; D055815:Young Adult