Active research has been conducted to resolve these practical issues (for reviews, see [157, 158]). Special efforts have been put forth upon devising MR-compatible EEG caps and amplifiers [152, 153], synchronizing the EEG sampling with fMRI pulses [159], EEG lead design and placement [155, 160, 161], cable wiring [152], signal transmitting [153, 162], subject comfort and safety [155, 163] etc. Signal processing algorithms have been developed to remove the GA [153, 164–168] and CBA [152, 154, 168–171] from the EEG simultaneously recorded with fMRI. Most of these methods are based on template matching/subtraction algorithms [153, 154, 164] or the blind source separation with principal component analysis [165–168] or independent component analysis [168, 170, 171]. Interleaved strategies are occasionally adopted to acquire fMRI data during the delayed time windows of little or no interest to EEG recordings [172, 173].
