title: BOLD-contrast functional MRI signal changes related to intermittent rhythmic delta activity in EEG during voluntary hyperventilation-simultaneous EEG and fMRI study.
abstract: Differences in the blood oxygen level dependent (BOLD) signal changes were studied during voluntary hyperventilation (HV) between young healthy volunteer groups, (1) with intermittent rhythmic delta activity (IRDA) (N = 4) and (2) controls (N = 4) with only diffuse arrhythmic slowing in EEG (normal response). Subjects hyperventilated (3 min) during an 8-min functional MRI in a 1.5-T scanner, with simultaneous recording of EEG (successful with N = 3 in both groups) and physiological parameters. IRDA power and average BOLD signal intensities (of selected brain regions) were calculated. Hypocapnia showed a tendency to be slightly lighter in the controls than in the IRDA group. IRDA power increased during the last minute of HV and ended 10-15 s after HV. The BOLD signal decreased in white and gray matter after the onset of HV and returned to the baseline within 2 min after HV. The BOLD signal in gray matter decreased approximately 30% more in subjects with IRDA than in controls, during the first 2 min of HV. This difference disappeared (in three subjects out of four) during IRDA in EEG. BOLD signal changes seem to depict changes, which precede IRDA. IRDA due to HV in healthy volunteers represent a model with a clearly defined EEG pattern and an observable BOLD signal change.
authors.affiliation: Department of Clinical Neurophysiology, Oulu University Hospital, University of Oulu, Kajaanintie 50, 90220 Oulu, Finland. Minna.Makiranta@oulu.fi
authors.forename: Minna J
authors.initials: MJ
authors.lastname: Mäkiranta
authors.forename: Jyrki
authors.initials: J
authors.lastname: Ruohonen
authors.forename: Kalervo
authors.initials: K
authors.lastname: Suominen
authors.forename: Eila
authors.initials: E
authors.lastname: Sonkajärvi
authors.forename: Timo
authors.initials: T
authors.lastname: Salomäki
authors.forename: Vesa
authors.initials: V
authors.lastname: Kiviniemi
authors.forename: Tapio
authors.initials: T
authors.lastname: Seppänen
authors.forename: Seppo
authors.initials: S
authors.lastname: Alahuhta
authors.forename: Ville
authors.initials: V
authors.lastname: Jäntti
authors.forename: Osmo
authors.initials: O
authors.lastname: Tervonen
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology / Q000502:physiology*; D004569:Electroencephalography / Q000706:statistics & numerical data*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006985:Hyperventilation / Q000378:metabolism / Q000503:physiopathology*; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D010092:Oximetry; D010100:Oxygen / Q000097:blood*
chemical_list: D010100:Oxygen