Environmental enrichment, particularly during the early life phases of enhanced neuroplasticity, can stimulate cognitive development. However, individuals exhibit considerable variation in their response to environmental enrichment. Recent evidence suggests that certain neurophenotypes such as hippocampal size may index inter-individual differences in sensitivity to environmental conditions. We conducted a prospective, longitudinal investigation in a cohort of 75 mother-child dyads to investigate whether neonatal hippocampal volume moderates the effects of the postnatal environment on cognitive development. Newborn hippocampal volume was quantified shortly after birth (26.2 ± 12.5 days) by structural MRI. Measures of infant environmental enrichment (assessed by the IT-HOME) and cognitive state (assessed by the Bayley-III) were obtained at 6 months of age (6.09 ± 1.43 months). The interaction between neonatal hippocampal volume and enrichment predicted infant cognitive development (b = 0.01, 95 % CI [0.00, 0.02], t = 2.08, p = .04), suggesting that exposure to a stimulating environment had a larger beneficial effect on cognitive outcomes among infants with a larger hippocampus as neonates. Our findings suggest that the effects of the postnatal environment on infant cognitive development are conditioned, in part, upon characteristics of the newborn brain, and that newborn hippocampal volume is a candidate neurophenotype in this context.

丰富环境，尤其是在神经可塑性增强的早期阶段，可以刺激认知发展。然而，个体对环境富集的反应表现出相当大的差异。最近的证据表明，某些神经表型，例如海马体大小，可能表明个体对环境条件敏感性的差异。我们在75个母子二元组的队列中进行了一项前瞻性纵向研究，以调查新生儿海马体积是否减轻了产后环境对认知发展的影响。出生后不久（26.2±12.5天）通过结构MRI定量新生儿海马体积。在6个月大时（6.09±1.43个月）获得了婴儿环境富集（由IT-HOME评估）和认知状态（由Bayley-III评估）的量度。新生儿海马体积与富集之间的相互作用预测了婴儿的认知发展（b = 0.01，95％CI [0.00，0.02]，t = 2.08，p = .04），表明暴露于刺激性环境对新生儿海马体较大的婴儿的认知结局具有较大的有益作用。我们的发现表明，产后环境对婴儿认知能力的影响部分取决于新生大脑的特征，在这种情况下，新生海马体积是候选的神经表型。