Discriminating Orientation Information with Phase Consistency in Alpha and Beta Frequency Bands: An EEG Study

Recent studies suggest that noninvasive imaging methods (EEG, MEG) in the human brain scalp can decode the content of visual information in Visual-Working-Memory (VWM). Previous work demonstrated that with the sustained low-frequency Event-Related Potential (under 6 Hz) of scalp distributions, it is possible to decode the content of orientation information in the delay interval. However, it is unclear whether the orientation information is available in the phase values of the signal. In the present study, we suggest that the orientation information is also possibly accessible from the phase consistency of the occipital region in alpha band frequency. We show that the significant difference between orientations has occurred under 200 ms after stimulus offset in early visual sensory, while no effect is apparent in power and Event-related oscillation (ERO) in this region and periods. In addition, in later periods (400 – 500 ms after stimulus offset), a noticeable difference is evident in the phase consistency of the beta-band activity in the occipital area. Our results indicate that the phase consistency between trials of the orientation feature in the occipital alpha and beta-band can be a measurement to obtain orientation information in VWM.