Rhythm Coherence Research Articles

Phase coherence of the alpha rhythm during photic blocking

The pre- to post-blocked phase angle relationship of the photically blocked alpha rhythm is examined in light of a pacemaker model. The question is asked whether this pacemaker is in continuous operation during photic blocking even though, within this period, the detected alpha oscillation may vanish. The analysis of the data shows first, a post-blocked alpha rhythm coherence and second, a mean zero phase angle between the post-blocked and pre-blocked wave trains. These results are consistent with the idea of a basic pacemaking system, but because of conservation of phase information during the photic block, they are at variance with the concept that photically induced desynchronization must take place at the pacemaker level. The results are discussed further in terms of a visual information intake model used by Gaarder et al.