新奇な刺激に触れることが発達に重要

未 development

Programming social, cognitive, and neuroendocrine development by early exposure to novelty

Tang AC, Akers KG, Reeb BC, Romeo RD, McEwen BS.

Proc Natl Acad Sci U S A. 2006 Oct 9; [Epub ahead of print]

Mildly stressful early life experiences can potentially impact a broad range of social, cognitive, and physiological functions in humans, nonhuman primates, and rodents. Recent rodent studies favor a maternal-mediation hypothesis that considers maternal-care differences induced by neonatal stimulation as the cause of individual differences in offspring development. Using neonatal novelty exposure, a neonatal stimulation paradigm that dissociates maternal individual differences from a direct stimulation effect on the offspring, we investigated the effect of early exposures to novelty on a diverse range of psychological functions using several assessment paradigms. Pups that received brief neonatal novelty exposures away from the home environment showed enhancement in spatial working memory, social competition, and corticosterone response to surprise during adulthood compared with their home-staying siblings. These functional enhancements in novelty-exposed rats occurred despite evidence that maternal care was directed preferentially toward home-staying instead of novelty-exposed pups, indicating that greater maternal care is neither necessary nor sufficient for these early stimulation-induced functional enhancements. We suggest a unifying maternal-modulation hypothesis, which distinguishes itself from the maternal-mediation hypothesis in that (i) neonatal stimulation can have direct effects on pups, cumulatively leading to long-term improvement in adult offspring; and (ii) maternal behavior can attenuate or potentiate these effects, thereby decreasing or increasing this long-term functional improvement.

幼少期の経験がどう発達に影響するかについて。従来の Maternal-Mediation Hypothesis は親からのケアの違いが発達に影響をもたらすと考えていたが、新奇な刺激に触れることのほうが種々の発達(空間的ワーキングメモリ、社会競争、コルチコステロン反応)に重要である、という知見。親からのケアは発達初期の刺激誘発性の機能強化においては、必要条件でも充分条件でもない。著者らの Maternal-Modulation Hypothesis: (i)新生児期の刺激は直接発達に作用し、累積的に長期の向上をもたらす (ii)親の行動はこうした効果を調整し、長期の機能向上を増強もしくは減弱する。


　
新生児が何に触れるか、という要因と、親がどうケアするか、というのは発達において別のファクターであり、直接作用するのは前者である、という。