Beyond the 30-Million-Word Gap: Children’s Conversational Exposure Is Associated With Language-Related Brain Function
研究通过家庭录音和功能性磁共振成像，发现4-6岁儿童与成人的对话次数越多，其左侧额下回（布罗卡区）激活越强，这解释了语言接触与语言技能的关系，且效应独立于社会经济地位和智商。
Children's early language exposure impacts their later linguistic skills, cognitive abilities, and academic achievement, and large disparities in language exposure are associated with family socioeconomic status (SES). However, there is little evidence about the neural mechanisms underlying the relation between language experience and linguistic and cognitive development. Here, language experience was measured from home audio recordings of 36 SES-diverse 4- to 6-year-old children. During a story-listening functional MRI task, children who had experienced more conversational turns with adults-independently of SES, IQ, and adult-child utterances alone-exhibited greater left inferior frontal (Broca's area) activation, which significantly explained the relation between children's language exposure and verbal skill. This is the first evidence directly relating children's language environments with neural language processing, specifying both an environmental and a neural mechanism underlying SES disparities in children's language skills. Furthermore, results suggest that conversational experience impacts neural language processing over and above SES or the sheer quantity of words heard.