Relevance of auditory cortical maturation to early language acquisition

我的实验室研究儿童大脑中的声音处理，以及这与他们的口语发展之间的关系。我们知道，同龄儿童的语言技能各不相同。通过用脑电图测量听觉诱发电位（AEPs），我们了解到，同年龄的儿童对声音的大脑反应也不同，这两种能力（听觉处理和语言）的复杂程度在某种程度上是相关的。先前的研究让该领域的许多人认为，大脑处理声音的能力会对儿童学习语言的方式产生因果影响。然而，研究尚未证实这种假设的影响方向。相反，大脑中更复杂的声音处理可能是儿童语言经验增长的结果，而我们之前的假设是错误的。*** ***在这个新的研究项目中，我将纵向研究早期语言习得过程中听觉和语言复杂程度之间的影响方向。为了做到这一点，我和我的学员将使用一个我们验证过的指标，并与我之前的NSERC资助的语言联系起来。这个指标是AEP-age，它是对儿童大脑对声音反应的年龄当量的估计。这个指标比传统方法有优势，因为它可以在最少的参与下获得，在5分钟内，对一个简单的音调做出反应，并且通过一种不需要识别听觉脑电波中单个峰值的分析方法。最后一个优势是关键，因为比较这个年龄段的孩子可能具有挑战性，因为这些峰值在形状、大小、方向和儿童的存在上都有所不同。使用这一指标，我们将收集12、18、24、30、36、48和62个月儿童群体的标准aep，以估计个体儿童反应的aep -年龄。然后，我们将跟踪18个月大的婴儿在aep年龄和语言能力方面的变化，直到他们长到48个月。这将使我们能够在一个纵向时期内检查这两个过程之间的影响方向。为了加强这种检查，我们不仅要研究表现出典型语言发展的儿童，还要研究那些能赶上的说话晚的儿童，以及那些持续迟缓的儿童。******了解影响的方向很重要。如果听觉的复杂性确实影响语言的复杂性，我们将有理由在未来的研究中更好地理解影响大脑听觉成熟的因素（如环境暴露和遗传），这些影响的时间，以及操纵它们（如果可能的话）是否会影响语言的发展。如果aep年龄在预测早期语言习得轨迹方面显示出希望，那么未来的研究可以通过检验临床翻译来预测哪些儿童在开始说话之前就有可能出现语言发展方面的问题。

My lab studies sound processing in children's brains and how this relates to their spoken language development. We know that children of the same age vary in their language skills. By measuring auditory-evoked potentials (AEPs) with electroencephalography, we have learned that children of the same age also vary in their brain responses to sounds, and that the sophistication of these two abilities (auditory processing and language) is somehow related. Prior research has led many in the field to assume that the brain's ability to process sounds causally influences how children learn language. However, research has yet to confirm this assumed direction of influence. Instead, it is possible that more sophisticated sound processing in the brain is a consequence of the child's growing experience with language, and that our prior assumptions have been wrong.*** ***In this new research program, I will longitudinally examine directions of influence between auditory and language sophistication during early language acquisition. To do this, my trainees and I will use a metric that we validated and linked to language with my prior NSERC funding. This metric is AEP-age, which is an estimate of the age equivalent of a child's brain response to sound. This metric has an advantage over traditional approaches because it can be acquired with minimal participation, in 5 minutes, in response to a simple tone, and via an analysis approach that does not require identifying individual peaks in the auditory brainwave. This last advantage is key because it can be challenging to compare children across this age range since these peaks can vary in shape, size, direction, and presence across children. Using this metric, we will gather normative AEPs from groups of children aged 12, 18, 24, 30, 36, 48 and 62 months to estimate the AEP-age of individual children's responses. Then we will track changes in both AEP-age and language ability in a group of 18 month olds until they reach 48 months. This will allow us to examine directions of influence between these two processes over a longitudinal period. To enhance this examination, we will not only study children showing typical language development but also late-talkers who catch up, and those with persistent delays. ******Understanding the direction of influence matters. If auditory sophistication indeed impacts language sophistication, we would be justified in dedicating future research efforts to better understanding the factors that influence auditory maturation in the brain (such as environmental exposures and genetics), the timing of these influences, and whether manipulating them (when possible) could impact language development. If AEP-age shows promise in predicting the trajectory of early language acquisition, future research could examine clinical translation into predicting which children are at risk for later problems in language development even before they begin talking.