女性月經(jīng)周期的性激素水平能夠影響大腦獎勵環(huán)路的敏感度。當女性不斷贏得獎勵的時候,，她們的大腦獎勵環(huán)路在雌性激素水平高的前排卵期比在雌性激素和黃體酮同時存在的后排卵期更加活躍,。《美國科學院院刊》1月29日在線報道了這項發(fā)現(xiàn),。
NIH美國國家精神健康研究院（NIMH）綜合神經(jīng)成像部主任Karen Berman博士說：“這是首次對影響大腦獎勵環(huán)路的荷爾蒙進行成像,，這也許有助于人們深入了解與月經(jīng)有關(guān)的情緒變化，為什么女性比男性更容易出現(xiàn)情緒波動和焦慮現(xiàn)象,，以及為什么女性精神分裂患者的比男性患者發(fā)病更晚,，而程度更輕。”
科學家們對照研究了13位女性和13位男性在玩老虎機時的大腦活動,，并且對照了女性在排卵前后的不同,。核磁共振大腦成像顯示女性在期望獎勵的時候，他們大腦的杏仁核以及控制感情和計劃的眼后皮層區(qū)在前排卵期（月經(jīng)結(jié)束后四至八天）比在后排卵期更加活躍,。而當女性贏錢的時候,，她們的紋狀體（Striatum）與快感和獎勵有關(guān)的回路部分在前排卵期比在后排卵期更加活躍。
研究人員還證實與獎勵有關(guān)的大腦活動與性激素水平直接相關(guān),。杏仁核和海馬區(qū)的活動與雌激素水平息息相關(guān),，而與月經(jīng)周期無關(guān)。
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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