Traveling EEG slow oscillation along the dorsal attention network initiates spontaneous perceptual switching

An ambiguous figure such as the Necker cube causes spontaneous perceptual switching (SPS). The mechanism of SPS in multistable perception has not yet been determined. Although early psychological studies suggested that SPS may be caused by fatigue or satiation of orientation, the neural mechanism of SPS is still unknown. Functional magnetic resonance imaging (fMRI) has shown that the dorsal attention network (DAN), which mainly controls voluntary attention, is involved in bistable perception of the Necker cube. To determine whether neural dynamics along the DAN cause SPS, we performed simultaneous electroencephalography (EEG) and fMRI during an SPS task with the Necker cube, with every SPS reported by pressing a button. This EEG–fMRI integrated analysis showed that (a) 3–4 Hz spectral EEG power modulation at fronto-central, parietal, and centro-parietal electrode sites sequentially appeared from 750 to 350 ms prior to the button press; and (b) activations correlating with the EEG modulation traveled along the DAN from the frontal to the parietal regions. These findings suggest that slow oscillation initiates SPS through global dynamics along the attentional system such as the DAN

Simultaneous and Continuous Recording of Electroencephalogram and Functional Magnetic Resonance Imaging and Their Clinical Applications

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\u27s 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