Second language learning has been shown to impact and reshape the central nervous system, anatomically and functionally. Most of the studies on second language learning and neuroplasticity have been focused on cortical areas, whereas the subcortical neural encoding mechanism and its relationship with L2 learning have not been examined extensively. The purpose of this study was to utilize frequency-following response (FFR) to examine if and how learning a tonal language in adulthood changes the subcortical neural encoding in hearing adults. Three groups of subjects were recruited: native speakers of Mandarin Chinese (native speakers (NS)), learners of the language (L2 learners), and those with no experience (native speakers of foreign languages (NSFL)). It is hypothesized that differences would exist in FFRs obtained from the three language experience groups. Results revealed that FFRs obtained from L2 learners were found to be more robust than the NSFL group, yet not on a par with the NS group. Such results may suggest that in human adulthood, subcortical neural encoding ability may be trainable with the acquisition of a new language and that neuroplasticity at the brainstem level can indeed be influenced by L2 learning.

中文翻译：

---

成年后学习第二语言会改变皮层下神经编码

第二语言学习已被证明会在解剖学和功能上影响和重塑中枢神经系统。大多数关于第二语言学习和神经可塑性的研究都集中在皮层区域，而皮层下神经编码机制及其与 L2 学习的关系尚未得到广泛研究。本研究的目的是利用频率跟随响应 (FFR) 来检查在成年期学习声调语言是否以及如何改变听力成人的皮层下神经编码。招募了三组受试者：汉语母语者（母语者（NS））、语言学习者（L2学习者）和没有经验的人（外语母语者（NSFL））。假设从三个语言经验组获得的 FFR 存在差异。结果显示，从 L2 学习者获得的 FFR 被发现比 NSFL 组更稳健，但与 NS 组不相上下。这样的结果可能表明，在人类成年期，皮层下神经编码能力可能会随着新语言的习得而得到训练，而且脑干水平的神经可塑性确实会受到二语学习的影响。