Spatial Alignment of Scalp EEG Activity during Cognitive Tasks

Electrocorticogram (ECoG) analysis of human subjects demonstrated that beta-gamma oscillations carry perceptual information in spatial patterns across the cortex when the subjects were engaged in task-oriented activities. A hypothesis was tested that similar patterns could be found in the scalp EEG of human subjects during visual stimulation. Signals were continuously recorded from scalp electrodes and band-pass filtered. The Fast Fourier transform provides the phase, which is used to obtain directional phase information relating to cognitive tasks. Spatial patterns of EEG phase modulation were identified and classified with respect to stimulus. The obtained results suggest that the scalp EEG can yield information about the timing of episodically synchronized brain activity in higher cognitive function, so as to support mechanisms of brain-computer interfacing.