Capacity of fetus for memory and learning

本研究旨在探讨在胎儿期直接注入羊水的味觉/气味刺激对新生小鼠记忆的影响。来自Slc的451只新生幼崽；采用ICR雌性小鼠，共设8个实验组，分别为3个实验组（VV、ApAp、SS）、3个对照组（NV、NAp、NS）、假手术组（sham）、完整组（NN）。VV组、ApAp组和SS组在胎儿期分别给予香草、苹果汁和生理盐水，出生后分别对香草、苹果汁和生理盐水进行偏好测试。NV组、NAp组和NS组在胎儿期不接受任何刺激，出生后分别测试对香草、苹果汁和生理盐水的偏好。在妊娠第16天，将0.025ml的味觉/气味刺激剂（香草、苹果汁或生理盐水）注射到每个胎儿鼻口附近的羊膜囊中。出生后第2天，麻醉母鼠乳头涂上香草、苹果汁或生理盐水，分别检测实验组和对照组新生幼鼠的刺激偏好。以NV组和VV组效果最为显著。当测试NV幼崽对香草的偏好时，它们会避开香草涂层的乳头。这表明香草对新生幼崽是一种厌恶的刺激。然而，在胎儿时期接触香草的VV幼崽并没有避免它们。苹果汁和生理盐水对幼鼠对它们的偏好没有影响。这些结果表明，胎儿能够记忆羊水中味道/气味的变化（特别是在厌恶刺激下），子宫内的产前环境对胎儿记忆的发育起着非常重要的作用。

This study was conducted in order to investigate whether the newborn mice remember the taste/odor stimulus directly injected into the amniotic fluid in their fetal period.The 451 newborn pups from Slc;ICR female mice were used and 8 subject groups was formed as follows: 3 experimental groups (VV, ApAp, and SS), 3 control groups (NV, NAp, and NS), sham operation group (Sham), and intact group (NN). The VV group, ApAp group, and SS group received vanilla, apple juice, and saline in fetal period and was tested the preference to vanilla, apple juice, and saline after birth, respectively. The NV group, NAp group, and NS,group was not received any stimulus in fetal period, but was tested the preference to vanilla, apple juice,,and saline after birth, respectively.On Day 16 of gestation, 0.025ml of taste/odor stimulus (vanilla, apple juice, or saline) was injected into the amniotic sac adjacent to the nose-mouth area of each fetus. On day 2 after birth, nipples of the anesthetized mother were coated with vanilla, apple juice or saline, and the stimulus preference of the newborn pups were tested in the experimental groups and control groups.The most remarkable results were obtained in the NV and VV groups. The NV pups avoided the vanilla coated nipples when their preference to vanilla was tested. It shows that vanilla is an aversive stimulus for the newborn pups. The VV pups, exposed to the vanilla in fetal period, however, did not avoid them. Apple juice and saline had no effect on the preference of pups to them. These results suggest that the fetuses can memorize the taste/odor change (especially in aversive stimulus) in the amniotic fluid, and that the prenatal environment in utero plays a very important role for the development of fetal memory.