Effects of menstrual cycle on electrophysiological correlates of selective auditory spatial attention
The fluctuations in steroid hormones associated with the female menstrual cycle have been suggested to modulate attentional brain processes. This study focused on cycle-dependent changes in the electrophysiological correlates of sound localization in a cocktail-party task, which has been shown to reflect the neural correlates of auditory selective attention. Event-related-potentials were recorded in three (1 - luteal, 2 - menses, 3 - follicular) phases (determined based on self-reports) in women not taking hormonal contraceptives, at three corresponding points in time in women taking oral hormonal contraceptives, and in men. An effect of phase in women was obtained exclusively for the N2 component, which may reflect processes of auditory selective spatial attention. N2 amplitudes were strongest in phase 1 (luteal phase or initial phase of pill intake) and lowest in phase 2 (menses or pause of pill intake). Compared with the male group, the N2 amplitudes were lower in women in phase 2, but not in phase 1 and 3. Cortical source localization at the time of the N2 revealed a related modulation of electrical activity in right superior frontal sulcus depending on phase. Also, electrical activity in left inferior frontal gyrus was increased in women in phase 2 compared with men. These findings suggest that the neural correlates of auditory selective spatial attention varied in women depending on their hormonal phase. The observed pattern is compatible with the view that higher concentrations of female steroid hormones enhance brain processes of selective spatial attention.