Does Reward Mediate Human Maternal Bonding? A PET-fMRI study

描述(申请人提供)：母亲和婴儿之间的纽带对孩子一生的身心健康有重要的长期影响。因此，支持最佳结合的社会和生物机制对儿童的最佳发展至关重要。我们团队之前的工作表明，伏隔核(NAcc)的大胆激活与母亲和婴儿之间的行为同步水平有关，这被认为是最佳结合的指标。在与婴儿同步的母亲中，NAcc对婴儿的反应比不同步的母亲更强，并与催产素血浆水平相关。NAcc和其他几个关键结构属于我们最近发现的社会联系网络；这个网络中内在的连接能力与更大的社会联系联系在一起。综合这些发现，我们提出了一个创新的模型，通过该模型，母婴同步导致NAcc和社会联系网络的其他区域中的催产素依赖的多巴胺释放。在这个R21应用中，我们计划使用一种创新的多学科方法来开始探索这一模型并测量它的四个组成部分：母婴同步性的行为评估，它与催产素(将在血浆中测量)有关，而催产素又与内源性多巴胺分泌和社会联系神经网络连接(通过联合fMRI-PET成像测量)有关。结合起来，它们将使我们能够评估这个社会联系网络中的解剖、内在连接和功能反应在多大程度上与同步联系在一起，这种联系是由多巴胺和催产素介导的，而多巴胺和催产素是这个网络中的关键神经递质。具体地说，我们计划研究在社会联系网络中具有更强连接性的母亲是否与她们的婴儿更同步(目标1)。我们还将评估同步母亲在观看自己婴儿的电影20分钟时与观看陌生婴儿时相比是否有更大的大胆反应(目标2)。此外，我们将评估婴儿相关刺激是否促进内源性多巴胺释放，以及同步母亲是否会有更多与催产素相关的内源性多巴胺释放，以回应她们的婴儿。我们还将探索社会联系网络中的哪些区域显示出最大的多巴胺结合(目标3)。了解母亲体内促进成功结合的神经生物学机制可能会显著降低儿童疾病的患病率，并增加孩子的幸福感。此外，这项拟议的研究将确立社会奖励是人类母性联系的一种机制，并将开始解析参与这一机制的神经化学。最后，本研究计划将PET和fMRI相结合的研究方法应用于人类行为的功能研究，并将其应用于儿童的发展。

DESCRIPTION (provided by applicant): The bonding between mothers and their infants have critical long term impacts on the child's physical and mental well-being across lifespan. Thus the social and biological mechanisms that support optimal bonding are critical for the child's optimal development. Prior work from our team has shown that BOLD activation in the nucleus accumbens (NAcc) is related to the level of behavioral synchronization between a mother and an infant, which is taken to be an indicator of optimal bonding. Among mothers who are synchronous with their infants, the response of the NAcc to the infant is stronger than among non-synchronous mothers, and is correlated with oxytocin plasma levels. The NAcc, along with several other key structures, belong to our recently discovered social affiliation network; strength of intrinsic connectivity within this network is linked to greater social connectedness. Synthesizing these findings, we propose an innovative model by which mother- infant synchrony leads to a oxytocin-dependent dopamine release in the NAcc and other regions of the social affiliation network. In this R21 application, we plan to use an innovative multi-disciplinary method as we begin to explore this model and measure its four components: behavioral assessments of mother-infant synchrony, which is linked to oxytocin (that will be measured in the plasma), which in turn is linked to endogenous dopamine secretion and social affiliation neural network connectivity (measured by combined fMRI-PET imaging). Together, they will allow us to assess the extent to which the anatomy, intrinsic connectivity, and functional response in this social affiliation network is linked to synchrony in a way that is mediated by dopamine and oxytocin, which are key neurotransmitters in this network. Specifically, we plan to examine if mothers with stronger connectivity in the social affiliation network are more synchronous with their infants (Aim 1). We will also evaluate whether synchronous mothers have a greater BOLD response in this network when viewing a film of their own infant for 20 minutes vs. when viewing an unfamiliar infant (Aim 2). Moreover, we will evaluate whether infant-related stimuli enhance endogenous dopamine release and whether synchronous mothers will have greater endogenous dopamine release that is correlated to oxytocin, in response to their infants. We will also explore which regions in the social affiliation network show the greatest dopamine binding (Aim 3). Understanding the neurobiological mechanisms in the mother that promote successful bonding may significantly reduce the prevalence of childhood illness and increases the child's wellbeing. Additionally, the proposed research will establish that social reward is a mechanism for human maternal affiliation, and it will begin to parse apart the neurochemistry involved in this mechanism. Last, this study plan to use a novel research methodology of combined PET and fMRI in the functional study of human behavior, and to utilize it in favor of children's development.