Female menstrual phases modulate human prefrontal asymmetry: A magnetoencephalographic study ☆ Ren-Jen Hwang a,b,c , Chi-Hsun Wu b,f , Li-Fen Chen b,d,e , Tzu-Chen Yeh b,d,e , Jen-Chuen Hsieh a,b,d,e, ⁎ a Institute of Neuroscience, School of Life Science, National Yang-Ming University, Taipei, Taiwan b Laboratory of Integrated Brain Research, Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan c Chang Gung Institute of Technology, Tao-Yuan, Taiwan d Brain Research Center, National Yang-Ming University, Taipei, Taiwan e Institute of Brain Science, School of Medicine, National Yang-Ming University, Taipei, Taiwan f Department of Electrical Engineering, National Central University, Jhongli, Taiwan abstract article info Article history: Received 1 September 2008 Revised 9 October 2008 Accepted 9 October 2008 Available online 1 November 2008 Keywords: Emotion Fear Menstrual cycle Frontal asymmetry Brain Magnetoencephalography We previously reported that the trait/baseline prefrontal cortex (PFC) activity expresses a dynamic plasticity during female menstrual cycle. The shift of asymmetric lateralization of PFC baseline activity pinpoints a possible emotional regulation of negative affection. The current emotional Go/NoGo study aimed to investigate the state PFC responses of different menstrual phases during fear facial stimulation in fourteen healthy women. Our data disclosed that the menstrual cycle was coupled with a shift of asymmetric lateralization of frontal activation across different menstrual phases. Evoked magnetic field activity in the time window 200–300 ms (M1) and 300–450 ms (M2) after stimulus onset demonstrated significant interactions between hemispheric side and menstrual phase. The right hemispheric dominance in periovulatory phase (OV) changed to left hemispheric dominance in menstrual (MC) phase. Significant association between the anxiety score and the left PFC activation was particularly observed in MC phase. Our study revealed a plastic resilience of functional organization of human brain and a dynamic automaticity of inter-hemispheric synergism for possible adaptive regulation under the aversive confrontation in accordance with hormonal fluctuation during the menstrual cycle. © 2008 Elsevier Inc. All rights reserved. Introduction Female's capability to regulate the negative emotion, an ability which is associated with women health or hedonic well-being with adaptation to the changing environments, has been considered one of the central functions of the prefrontal cortex (PFC) (Davidson et al., 2000; Keenan et al., 2001). It has been postulated that the left and right anterior regions of the brain are parts of two separate neural systems underlying approach and withdrawal (promotion vs. preven- tion) motivation, respectively (Amodio 2004; Davidson et al., 2000; Eddington et al., 2007; Higgins, 1997). Gonadal steroid hormones vary systematically during the menstrual cycle and can influence neuronal activity, which in turn may be responsible for cyclic modulation of mood or affective processing (Dreher et al., 2007; Protopopescu et al., 2005). However, the exact relationship between different menstrual phases and the PFC lateralization for negative emotional processing remains undocumented. Kline et al. (2007) proposed that a greater left frontal baseline activity may reflect a protective factor against maladaptive responses to stress. Subjects with higher left frontal baseline activity may show a significant increase in the left anterior activation from aversive to recovery condition and are better in stress adjustment and emotional regulation, resulting in a reduced occurrence of psychological and/or physiological dysfunction (Davidson, 2003; Jackson et al., 2003). It has also been reported that greater left PFC activity can be associated with lower metabolic activity in the amygdale (Davidson et al., 2000) and can manifest a top-down coping or inhibition of negative reactivity (Jackson et al., 2003). However, our recent study reported that female hormone cycle may influence the resting PFC activity; relative higher left frontal activation during menstruation phase (MC) as compared with the periovulatory phase (OV) (Hwang et al., 2008). The shift of asymmetric lateralization of PFC baseline activity pinpoints a possible emotional regulation of negative affection to meet with different demand across menstrual cycle. The emotional Go/NoGo task can serve as an effective probe for frontal lobe functions (Swainson et al., 2003; Watanabe et al., 2002). Fear facial expression may invoke biological stress responses (Lerner et al., 2007). The fear facial NoGo task has been used to elicit negative emotion as compared with passively viewing simple unpleasant pictures for the NoGo condition (Boecker et al., 2007; Phan et al., Hormones and Behavior 55 (2009) 203–209 ☆ MEG study of prefrontal activity across menstrual cycle. ⁎ Corresponding author. Brain Research Center and Institute of Brain Science, School of Medicine, National Yang-Ming University, No.155, Sect. 2, Linong Street, Taipei 112, Taiwan. Fax: +886 2 28757480. E-mail addresses: rjhwang2@vghtpe.gov.tw (R.-J. Hwang), jchsieh@ym.edu.tw (J.-C. Hsieh). 0018-506X/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.yhbeh.2008.10.008 Contents lists available at ScienceDirect Hormones and Behavior journal homepage: www.elsevier.com/locate/yhbeh