Author: Anami K 1//Zhang T 3//Mori T 1//Kobayashi Y 1////
Affiliation: Dept. of Psychiatry, National Center Hospital for Mental, Nervous, and Muscular Disorders, NCNP. (Tokyo, Japan) [1]//Dept. of Radiology, National Center Hospital for Mental, Nervous, and Muscular Disorders, NCNP. (Tokyo, Japan) [2]//National Institute of Radiological Sciences (Chiba, Japan) [3]
Conference/Journal: J Intl Soc Life Info Science
Date published: 2003
Other:
Volume ID: 21 , Issue ID: 1 , Pages: 106-109 , Word Count: 163
Simultaneous and continuous recording of an electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) can allow brain mapping that reveals brain regions related to a variety of EEG events such as alpha activity, sleep spindle and event related potentials as well as epileptic discharges. However, this methodology is precluded by artifacts on EEG such as ballistocardiograms, and other imaging artifacts that often have overwhelming amplitudes of 1000 to 2500 mV. Recording the imaging artifacts with frequency range up to 3000 Hz revealed their real waveform, in which each major artifact peak precisely corresponded to each gradient component. It was elucidated that the imaging artifacts actually had differential waveforms of the original gradient pulses based on Faraday’s law. Given the above findings, to retrieve EEG signal during fMRI acquisition, a new blip type echo planar sequence (stepping stone sequence) was developed2) so that every EEG data sampling (1000 Hz digitization rate) might be performed exclusively in interspaces in which an imaging artifact resided near the baseline level.