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

Abstract

The aim of the present study was to compare the EEG signal recorded outside and inside a 1.5T magnetic resonance (MR) scanner. The EEG was recorded in eyes open and eyes closed conditions using a digital recording MR-compatible system. To characterize how a static magnetic field induces changes in EEG signal, EEG data were analyzed using FFT frequency analysis. No significant difference between the alpha powers recorded outside and inside the magnetic field was observed in eyes closed conditions. However, in eyes open condition there was a significant increase in alpha power inside the magnet in comparison to the outside position. The changes in alpha power according to the eyes open/closed conditions could be inversely correlated to a subject's state of wakefulness and due to some physiological changes, rather than an effect of the magnetic field. This experiment suggests that subjects' state of wakefulness is of prime concern when performing functional MRI.

Keywords

EEG alpha power static magnetic field artifact

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References

Henning

Merboldt

Frahm

: Task and EEG-correlated analyses of BOLD MRI responses to eyes opening and closing. Brain Res 1073–1074: 359–64, 2006.

Allen

Polizzi

Krakow

: Identification of EEG events in the MR scanner: the problem of pulse artifact and a method for its subtraction. Neuroimage 8: 229–239, 1998.

Allen

Josephs

Turner

: A Method for Removing Imaging Artifact from Continuous EEG Recorded during Functional MRI. Neuroimage 12: 230–239, 2000.

Lemieux

Allen

Franconi

: Recording of EEG during fMRI experiments: patient safety. Magn Reson Med 38: 943–952, 1997.

Ives

Warach

Schmitt

: Monitoring the patient's EEG during echo planar MRI. Neurophysiol 87: 417–420, 1993.

Goldman

Stern

Engel

: Acquiring simultaneous EEG and functional MRI. Neurophysiol 111: 1974–1980, 2000.

Muri

Felblinger

Rosler

: Recording of electrical brain activity in a magnetic resonance environment: distorting effects of the static magnetic field. Magn Reson Med 39: 18–22, 1998.

Feige

Scheffler

Esposito

: Cortical and subcortical correlates of electroencephalographic alpha rhythm modulation. J Neurophysiol 93: 2864–2872, 2005.

Laufs

Kleinschmidt

Beyerle

: EEG-correlated fMRI of human alpha activity. Neuroimage 19: 1463–1476, 2003.

10.

Laufs

Krakow

Sterzer

: Electroencephalographic signatures of attentional and cognitive default modes in spontaneous brain activity fluctuations at rest. Proc Natl Acad Sci USA 100: 11053–11058, 2003.

11.

Moosmann

Ritter

Krastel

: Correlates of alpha rhythm in functional magnetic resonance imaging and near infrared spectroscopy. Neuroimage 20: 145–158, 2003.

12.

Rechtschaffen

Siegel

: Sleep and dreaming. In: Kandel

Schwartz

Jessel

: Principles of Neural Science. McGraw-Hill 2000: 936–947.

13.

Avesani

Milanese

Formaggio

: Continuous EEG-fMRI in Pre-Surgical Evaluation of a Patient with Symptomatic Seizures: Bold Activation Linked to Interictal Epileptic Discharges Caused by Cavernoma. The Neuroradiology Journal 21: 183–191, 2008.

14.

Gonçalves

de Munck

Pouwels

PJW

: Correlating the alpha rhythm to BOLD using simultaneous EEG/fMRI: Inter-subject variability. Neuroimage 30: 203–213, 2006.

15.

Manganotti

Formaggio

Milanese

: Continuous EEG-fMRI study in patients with partial epilepsy and focal interictal slow-wave discharges on EEG. Magnetic Resonance Imaging 26: 1089–100, 2008.

16.

Chatrian

Bergamini

Dondey

: A glossary of terms most commonly used by clinical electroen-cephalographers. Electroencephalogr Clin Neurophysiol 37: 538–548, 1974.

17.

Andreansen

O'Leary

Cizadlo

: Remembering the past: two facets of episodic memory explored with positron emission tomography. Am J Psychiatry 152: 1576–1585, 1995.

18.

Binder

Frost

Hammeke

: Conceptual processing during the conscious resting state: a functional MRI study. J Cogn Neurosci 11: 80–93, 1999.

19.

Christoff

Ream

Gabrieli

JDE

: Neural basis of spontaneous thought processes. Cortex 40: 623–630, 2004.

20.

Klimesch

: EEG alpha and theta oscillations reflect cognitive and memory performance: a review and analysis. Brain Res Rev 29: 169–195, 1999.

21.

Parkers

Bastiaansen

Norris

: Combining EEG and fMRI to investigate the post-movement beta rebound. Neuroimage 29: 685–696, 2006.

22.

Gevins

Zeitlin

Doyle

: Electroencephalogram correlates of higher cortical functions. Science 203: 665–8, 1979.

23.

Haik

Pai

Chen

C-J

: Apparent viscosity of human blood in a high static magnetic field. J Magn Mater 225: 180–186, 2001.

24.

Yamamoto

Nagayama

Tamura

: A blood-oxy-genation-dependent increase in blood viscosity due to a static magnetic field. Phys Med Biol 49: 3267–3277, 2004.