Laboratory for Affiliative Social Behavior, RIKEN Center for Brain Science, 351-0198, Saitama, Japan.
Laboratory for Human Cognition and Learning, RIKEN Center for Brain Science, Saitama, 351-0198, Japan.
J Physiol Sci. 2023 Mar 14;73(1):3. doi: 10.1186/s12576-023-00860-w.
The mother-infant relation is key to infant physical, cognitive and social development. Mutual regulation and cooperation are required to maintain the dyadic system, but the biological foundation of these responses remains to be clarified. In this study, we report the maternal calming responses to infant suckling during breastfeeding. Using behavioral measures and a Holter electrocardiogram as a readout of the maternal autonomic nervous system, the maternal activities during resting, sitting with her infant on her lap, and breastfeeding were assessed. We found that during breastfeeding, mothers talked less and maternal heart rate was lower than during sitting with the infant without breastfeeding. Congruently, maternal heart rate variability measurements indicated a higher parasympathetic activity during breastfeeding. Time-locked analyses suggested that this maternal calming response was initiated by the tactile stimulation at the breast by the infant face or mouth latch, which preceded the perceived milk ejection. These findings suggest that somatosensory stimuli of breastfeeding activate parasympathetic activity in mothers. Just as how the infant Transport Response facilitates the carrying of infants, the maternal calming responses during breastfeeding may promote efficient milk intake by inhibiting spontaneous maternal activities.
母婴关系是婴儿生理、认知和社会发展的关键。母婴之间需要相互调节和合作来维持这种二元系统，但这些反应的生物学基础仍有待阐明。在这项研究中，我们报告了母亲在母乳喂养过程中对婴儿吮吸的安抚反应。我们使用行为测量和动态心电图（Holter 心电图）作为母亲自主神经系统的读数，评估了母亲在休息、与婴儿坐在腿上和母乳喂养时的活动。我们发现，在母乳喂养期间，母亲说话较少，心率低于与婴儿不哺乳时坐在腿上的情况。一致的是，母亲心率变异性测量结果表明，母乳喂养期间副交感神经活动更高。时间锁定分析表明，这种母亲的平静反应是由婴儿的面部或口腔衔乳时对乳房的触觉刺激引起的，这先于感知到的奶液喷射。这些发现表明，母乳喂养的躯体感觉刺激会激活母亲的副交感神经活动。正如婴儿的转运反应促进婴儿的携带一样，母乳喂养期间的母亲平静反应可能通过抑制自发的母亲活动来促进有效的乳汁摄入。
