Effect of a Static Magnetic Field (1.5T) on Brain Oscillatory Activities in Resting State Condition

Area of Science:

• Neuroscience
• Medical Imaging
• Biophysics

Background:

• Magnetic Resonance (MR) scanners generate strong static magnetic fields.
• Electroencephalography (EEG) measures brain electrical activity.
• Understanding MR's effect on EEG is crucial for combined functional MRI (fMRI) and EEG studies.

Purpose of the Study:

• To compare EEG signals recorded inside and outside a 1.5T MR scanner.
• To investigate the influence of static magnetic fields on EEG alpha power.
• To determine if observed EEG changes are due to the magnetic field or physiological state.

Main Methods:

• EEG was recorded using a digital, MR-compatible system in both eyes open and eyes closed conditions.
• Recordings were performed both inside and outside a 1.5T MR scanner.
• Fast Fourier Transform (FFT) frequency analysis was used to analyze EEG data, focusing on alpha power.

Main Results:

• No significant difference in alpha power was found between inside and outside the MR scanner in the eyes-closed condition.
• A significant increase in alpha power was observed inside the MR scanner compared to outside in the eyes-open condition.
• Observed alpha power changes correlated with the eyes open/closed state, suggesting a link to wakefulness.

Conclusions:

• The observed changes in EEG alpha power within the MR scanner are likely related to the subject's state of wakefulness rather than a direct effect of the static magnetic field.
• Subject's state of wakefulness is a critical factor to consider when interpreting EEG data acquired during functional MRI (fMRI) scans.
• Further research is needed to fully elucidate the interplay between magnetic fields, physiological states, and EEG signals in MR environments.