女性月经周期的性激素水平能够影响大脑奖励环路的敏感度。当女性不断赢得奖励的时候,她们的大脑奖励环路在雌性激素水平高的前排卵期比在雌性激素和黄体酮同时存在的后排卵期更加活跃。《美国科学院院刊》1月29日在线报道了这项发现。
NIH美国国家精神健康研究院(NIMH)综合神经成像部主任Karen Berman博士说:“这是首次对影响大脑奖励环路的荷尔蒙进行成像,这也许有助于人们深入了解与月经有关的情绪变化,为什么女性比男性更容易出现情绪波动和焦虑现象,以及为什么女性精神分裂患者的比男性患者发病更晚,而程度更轻。”
科学家们对照研究了13位女性和13位男性在玩老虎机时的大脑活动,并且对照了女性在排卵前后的不同。核磁共振大脑成像显示女性在期望奖励的时候,他们大脑的杏仁核以及控制感情和计划的眼后皮层区在前排卵期(月经结束后四至八天)比在后排卵期更加活跃。而当女性赢钱的时候,她们的纹状体(Striatum)与快感和奖励有关的回路部分在前排卵期比在后排卵期更加活跃。
研究人员还证实与奖励有关的大脑活动与性激素水平直接相关。杏仁核和海马区的活动与雌激素水平息息相关,而与月经周期无关。
部分英文原文:
Menstrual cycle phase modulates reward-related neural function in women
Jean-Claude Dreher , Peter J. Schmidt , Philip Kohn , Daniella Furman , David Rubinow , and Karen Faith Berman ¶
Section on Integrative Neuroimaging and Behavioral Endocrinology Branch, National Institute of Mental Health, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892
Edited by Bruce S. McEwen, The Rockefeller University, New York, NY, and approved November 21, 2006 (received for review July 4, 2006)
There is considerable evidence from animal studies that the mesolimbic and mesocortical dopamine systems are sensitive to circulating gonadal steroid hormones. Less is known about the influence of estrogen and progesterone on the human reward system. To investigate this directly, we used functional MRI and an event-related monetary reward paradigm to study women with a repeated-measures, counterbalanced design across the menstrual cycle. Here we show that during the midfollicular phase (days 4-8 after onset of menses) women anticipating uncertain rewards activated the orbitofrontal cortex and amygdala more than during the luteal phase (6-10 days after luteinizing hormone surge). At the time of reward delivery, women in the follicular phase activated the midbrain, striatum, and left fronto-polar cortex more than during the luteal phase. These data demonstrate augmented reactivity of the reward system in women during the midfollicular phase when estrogen is unopposed by progesterone. Moreover, investigation of between-sex differences revealed that men activated ventral putamen more than women during anticipation of uncertain rewards, whereas women more strongly activated the anterior medial prefrontal cortex at the time of reward delivery. Correlation between brain activity and gonadal steroid levels also revealed that the amygdalo-hippocampal complex was positively correlated with estradiol level, regardless of menstrual cycle phase. Together, our findings provide evidence of neurofunctional modulation of the reward system by gonadal steroid hormones in humans and establish a neurobiological foundation for understanding their impact on vulnerability to drug abuse, neuropsychiatric diseases with differential expression across males and females, and hormonally mediated mood disorders.
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