EEG gamma-band phase synchronization between posterior and frontal cortex during mental rotation in humans

The main purpose of the present paper was: (1) to study the phase synchroni zation pattern in the gamma -band while performing the classical Shepard-Me tzler task of mental rotation; (2) to investigate the role of musical train ing; and (3) to study hemispheric differences in the degree of synchronizat ion during mental rotation. Multivariate electroencephalograph signals from 20 male subjects (ten musicians and ten non-musicians) were recorded while performing the mental rotation task and also at resting condition. Phase s ynchronization was measured by a recent index, mean phase coherence. It was found that synchronization between frontal cortex and right parietal corte x was significantly increased during mental rotation with respect to rest, whereby musicians showed significantly higher degrees of synchronization th an non-musicians. Left hemispheric dominance in the degree of phase synchro nization, stronger in the posterior right parietal and occipital regions, w as observed in musicians. Right hemispheric dominance was generally observe d in nonmusicians. (C) 2001 Elsevier Science Ireland Ltd. All rights reserv ed.