Robinson-Drummer Patrese A, Opendak Maya, Blomkvist Anna, Chan Stephanie, Tan Stephen, Delmer Cecilia, Wood Kira, Sloan Aliza, Jacobs Lily, Fine Eliana, Chopra Divija, Sandler Chaim, Kamenetzky Giselle, Sullivan Regina M
Emotional Brain Institute, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, United States.
Department of Child and Adolescent Psychiatry, Child Study Center at NYU Langone Medical Center, NYU School of Medicine, New York, NY, United States.
Front Behav Neurosci. 2019 Jun 21;13:132. doi: 10.3389/fnbeh.2019.00132. eCollection 2019.
Within the infant-caregiver attachment system, the primary caregiver holds potent reward value to the infant, exhibited by infants' strong preference for approach responses and proximity-seeking towards the mother. A less well-understood feature of the attachment figure is the caregiver's ability to reduce fear social buffering, commonly associated with the notion of a "safe haven" in the developmental literature. Evidence suggests this infant system overlaps with the neural network supporting social buffering (attenuation) of fear in the adults of many species, a network known to involve the prefrontal cortex (PFC). Here, using odor-shock conditioning in young developing rats, we assessed when the infant system transitions to the adult-like PFC-dependent social buffering of threat system. Rat pups were odor-shock conditioned (0.55 mA-0.6 mA) at either postnatal day (PN18; dependent on mother) or 28 (newly independent, weaned at PN23). Within each age group, the mother was present or absent during conditioning, with PFC assessment following acquisition using C 2-DG autoradiography and cue testing the following day. Since the human literature suggests poor attachment attenuates the mother's ability to socially buffer the infants, half of the pups at each age were reared with an abusive mother from PN8-12. The results showed that for typical control rearing, the mother attenuated fear in both PN18 and PN28 pups, although the PFC [infralimbic (IL) and ventral prelimbic (vPL) cortices] was only engaged at PN28. Abuse rearing completely disrupted social buffering of pups by the mother at PN18. The results from PN28 pups showed that while the mother modulated learning in both control and abuse-reared pups, the behavioral and PFC effects were attenuated after maltreatment. Our data suggest that pups transition to the adult-like PFC social support circuit after independence from the mother (PN28), and this circuit remains functional after early-life trauma, although its effectiveness appears reduced. This is in sharp contrast to the effects of early life trauma during infancy, where social buffering of the infant is more robustly impacted. We suggest that the infant social buffering circuit is disengaged by early-life trauma, while the adolescent PFC-dependent social buffering circuit may use a safety signal with unreliable safety value.
在婴儿-照顾者依恋系统中，主要照顾者对婴儿具有强大的奖赏价值，这表现为婴儿强烈倾向于接近母亲并寻求与母亲亲近。依恋对象一个尚未被充分理解的特征是照顾者减轻恐惧的能力——社会缓冲，这在发展心理学文献中通常与“安全港湾”的概念相关联。有证据表明，这种婴儿系统与支持许多物种成年个体恐惧社会缓冲（减轻）的神经网络重叠，已知该网络涉及前额叶皮层（PFC）。在此，我们利用幼龄发育大鼠的气味-电击条件反射，评估婴儿系统何时转变为类似成年个体的依赖PFC的威胁系统社会缓冲。将幼鼠在出生后第18天（依赖母亲）或第28天（刚独立，在出生后第23天断奶）进行气味-电击条件反射（0.55毫安 - 0.6毫安）。在每个年龄组中，条件反射过程中母亲在场或不在场，习得后使用碳 - 2 - 脱氧葡萄糖放射自显影术评估PFC，并在第二天进行线索测试。由于人类文献表明不良依恋会削弱母亲对婴儿进行社会缓冲的能力，每个年龄组的幼鼠中有一半从出生后第8天到第12天由虐待性母亲抚养。结果表明，对于典型的对照饲养，母亲在出生后第18天和第28天的幼鼠中都减轻了恐惧，尽管PFC[眶下（IL）和腹侧前边缘（vPL）皮层]仅在出生后第28天被激活。虐待性饲养在出生后第18天完全破坏了母亲对幼鼠的社会缓冲。出生后第28天幼鼠的结果表明，虽然母亲在对照饲养和虐待饲养的幼鼠中都调节了学习，但虐待后行为和PFC效应减弱。我们的数据表明，幼鼠在脱离母亲独立（出生后第28天）后转变为类似成年个体的依赖PFC的社会支持回路，并且该回路在早期生活创伤后仍然起作用，尽管其有效性似乎降低了。这与婴儿期早期生活创伤的影响形成鲜明对比，在婴儿期，婴儿的社会缓冲受到更强烈的影响。我们认为，婴儿社会缓冲回路因早期生活创伤而脱离，而青少年依赖PFC的社会缓冲回路可能使用具有不可靠安全价值的安全信号。
