In mothers, offspring cues are associated with a powerful reinforcing value that motivates maternal care. Animal studies show that this is mediated by dopamine release into the nucleus accumbens, a core component of the brain's reward system located in the ventral striatum (VStr). The VStr is also known to respond to infant signals in human mothers. However, it is unknown whether pregnancy modifies the anatomy or functionality of this structure, and whether such modifications underlie its strong reactivity to offspring cues. Therefore, we analyzed structural and functional neuroimaging data from a unique pre-conception prospective cohort study involving first-time mothers investigated before and after their pregnancy as well as nulliparous control women scanned at similar time intervals. First, we delineated the anatomy of the VStr in each subject's neuroanatomical space and examined whether there are volumetric changes in this structure across sessions. Then, we tested if these changes could predict the mothers' brain responses to visual stimuli of their infants. We found decreases in the right VStr and a trend for left VStr reductions in the women who were pregnant between sessions compared to the women who were not. Furthermore, VStr volume reductions across pregnancy were associated with infant-related VStr responses in the postpartum period, with stronger volume decreases predicting stronger functional activation to offspring cues. These findings provide the first indications that the transition to motherhood renders anatomical adaptations in the VStr that promote the strong responsiveness of a mother's reward circuit to cues of her infant.

中文翻译：

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成为母亲需要人脑腹侧纹状体的解剖学变化，促进其对后代线索的反应

在母亲身上，后代暗示与激励母亲照顾的强大强化价值相关联。动物研究表明，这是由多巴胺释放到伏隔核介导的，伏隔核是位于腹侧纹状体 (VStr) 的大脑奖赏系统的核心组成部分。众所周知，VStr 也会对人类母亲的婴儿信号做出反应。然而，尚不清楚怀孕是否会改变这种结构的解剖结构或功能，以及这种改变是否是其对后代线索的强烈反应的基础。因此，我们分析了来自一项独特的受孕前前瞻性队列研究的结构和功能神经影像数据，该研究涉及怀孕前后调查的首次生育母亲以及以相似时间间隔扫描的未生育对照妇女。第一的，我们在每个受试者的神经解剖空间中描绘了 VStr 的解剖结构，并检查了该结构在整个会话中是否存在体积变化。然后，我们测试了这些变化是否可以预测母亲对婴儿视觉刺激的大脑反应。我们发现，与未怀孕的女性相比，在治疗期间怀孕的女性的右侧 VStr 减少，左侧 VStr 减少的趋势。此外，怀孕期间 VStr 的体积减少与产后婴儿相关的 VStr 反应相关，体积减少越强，预示对后代线索的功能激活越强。这些发现提供了第一个迹象，即向母性的过渡使 VStr 的解剖结构适应，从而促进了母亲的强烈反应