Nathan Kline Institute for Psychiatric Research and Child & Adolescent Psychiatry, New York University School of Medicine, Orangeburg, NY 10962, USA.
Dev Psychobiol. 2010 Nov;52(7):651-60. doi: 10.1002/dev.20482.
Here we review the neurobiology of infant odor learning in rats, and discuss the unique role of the stress hormone corticosterone (CORT) in the learning necessary for the developing rat. During the first 9 postnatal (PN) days, infants readily learn odor preferences, while aversion and fear learning are attenuated. Such restricted learning may ensure that pups only approach their mother. This sensitive period of preference learning overlaps with the stress hyporesponsive period (SHRP, PN4-14) when pups have a reduced CORT response to most stressors. Neural underpinnings responsible for sensitive-period learning include increased activity within the olfactory bulb and piriform "olfactory" cortex due to heightened release of norepinephrine from the locus coeruleus. After PN10 and with the decline of the SHRP, stress-induced CORT release permits amygdala activation and facilitates learned odor aversions and fear. Remarkably, odor preference and attenuated fear learning can be reestablished in PN10-15 pups if the mother is present, an effect due to her ability to suppress pups' CORT and amygdala activity. Together, these data indicate that functional changes in infant learning are modified by a unique interaction between the developing CORT system, the amygdala, and maternal presence, providing a learning system that becomes more flexible as pups mature.
在这里，我们回顾了大鼠婴儿气味学习的神经生物学，并讨论了应激激素皮质酮（CORT）在发育中大鼠学习过程中的独特作用。在出生后的第 9 天内，婴儿很容易学习气味偏好，而厌恶和恐惧学习则减弱。这种受限的学习可以确保幼崽只接近它们的母亲。这种偏好学习的敏感时期与应激反应迟钝期（SHRP，PN4-14）重叠，在此期间，幼崽对大多数应激源的皮质酮反应降低。负责敏感时期学习的神经基础包括由于蓝斑核释放去甲肾上腺素增加，嗅球和梨状“嗅觉”皮层内的活动增加。在 PN10 之后，随着 SHRP 的下降，应激引起的 CORT 释放允许杏仁核激活，并促进习得的气味厌恶和恐惧。值得注意的是，如果母亲在场，PN10-15 日龄的幼崽可以重新建立气味偏好和减弱的恐惧学习，这是由于她能够抑制幼崽的 CORT 和杏仁核活动的能力所致。总之，这些数据表明，婴儿学习的功能变化是由发育中的 CORT 系统、杏仁核和母体存在之间的独特相互作用所调节的，为幼崽成熟时变得更加灵活的学习系统提供了依据。
