Observation of changes in neural activity due to the static magnetic field of an MRI scanner.
OBJECTIVE
To clarify whether a strong static magnetic field affects brain activity such as arousal level.


METHODS
We compared the electroencephalography (EEG) inside an MRI scanner in the presence/absence of the static magnetic field in two different arousal levels of task and rest conditions. Cardiac-related pulsations of head and blood flow induce an electric voltage at each EEG electrode in a static magnetic field. This induced voltage overlaps with the intrinsic EEG signal and becomes a large confounding factor. To extract the information of the intrinsic EEG from the contaminated EEG data measured in a static magnetic field, we developed a new analysis method.


RESULTS
No significant difference was observed in the intrinsic EEG in the absence of a magnetic field, whereas in the presence of the static magnetic field, the theta frequency band of the intrinsic EEG increased, especially during the task condition, but other frequency bands did not change.


CONCLUSIONS
Our results demonstrate that a static magnetic field affects brain activity.
Toyomaki
Atsuhito
A
Department of Psychiatry, Graduate School of Medicine, Hokkaido University, Sapporo, Japan. toyomaki@gmail.com
Yamamoto
Toru
T
D000328:Adult; D001143:Arousal / Q000502:physiology* / Q000528:radiation effects*; D001921:Brain / Q000502:physiology* / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D004569:Electroencephalography / Q000528:radiation effects*; D004574:Electromagnetic Fields; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage