一项研究发现，在子宫内听到的声音可能塑造发育中的人类大脑，从而影响人出生后的语音和语言发育。人类胎儿在怀孕后大约27周开始感受到外部声音，引发胎儿听觉皮层重新组织以及正在发育的神经系统的成熟。但是胎儿是否能够学习这些声音从而影响在婴儿期的语音感受和发育，这仍然不清楚。Eino Partanen及其同事探索了胎儿期的经历如何影响胎儿进行学习的神经基础的，而该学记过程会响应胎儿在子宫内听到的声音。这组作者对33名芬兰女性从怀孕第29周直到出生进行了跟踪。其中半数母亲每周聆听几次重复数百遍的假词“tatata”的简短录音，有时候中间那个音节被替换为“to”或者以不同的音调发出。在出生后，比较了在子宫中曾经接触过这些发音和没有接触过这些发音的新生儿对这个假词以及不熟悉的发音变化的神经响应。这些发现提示胎儿的大脑具有在出生前进行听觉学习的能力，并且出现了结构变化，导致了可能在婴儿期影响语言习得的神经记忆踪迹。这组作者说，这些发现可能为着眼于预防未来的语言障碍或帮助缓解诵读困难等遗传疾病的干预手段提供信息。（生物谷 Bioon.com）
生物谷推荐的英文摘要
PNAS doi: 10.1073/pnas.1302159110
Learning-induced neural plasticity of speech processing before birth
Eino Partanena,b,1, Teija Kujalaa,c, Risto Näätänena,d,e, Auli Liitolaa, Anke Sambethf, and Minna Huotilainena,b,g
Learning, the foundation of adaptive and intelligent behavior, is based on plastic changes in neural assemblies, reflected by the modulation of electric brain responses. In infancy, auditory learning implicates the formation and strengthening of neural long-term memory traces, improving discrimination skills, in particular those forming the prerequisites for speech perception and understanding. Although previous behavioral observations show that newborns react differentially to unfamiliar sounds vs. familiar sound material that they were exposed to as fetuses, the neural basis of fetal learning has not thus far been investigated. Here we demonstrate direct neural correlates of human fetal learning of speech-like auditory stimuli. We presented variants of words to fetuses; unlike infants with no exposure to these stimuli, the exposed fetuses showed enhanced brain activity (mismatch responses) in response to pitch changes for the trained variants after birth. Furthermore, a significant correlation existed between the amount of prenatal exposure and brain activity, with greater activity being associated with a higher amount of prenatal speech exposure. Moreover, the learning effect was generalized to other types of similar speech sounds not included in the training material. Consequently, our results indicate neural commitment specifically tuned to the speech features heard before birth and their memory representations.
