Asymmetry in EEG alpha coherence and power: effects of task and sex.

Male and female subjects performed two spatial and two verbal tasks while EEG was recorded from right and left temporal and parietal sites. Measures of alpha band power asymmetry, coherence and phase angle were derived. Spatial tasks produced increased coherence within the right hemisphere. Interhemispheric coherence was higher for females, and at parietal than at temporal sites. Power asymmetry effects confirmed previous findings, reflected upon sex differences in cerebral lateralisation and upon strategies associated with functional cerebral organisation for task performance. The relation to performance studies and the value of the method in investigating dynamic functional organisation are discussed.