Krishnan Ananthanarayan, Xu Yisheng, Gandour Jackson, Cariani Peter
Department of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, IN 47907-2038, USA.
Brain Res Cogn Brain Res. 2005 Sep;25(1):161-8. doi: 10.1016/j.cogbrainres.2005.05.004.
Neural processes underlying pitch perception at the level of the cerebral cortex are influenced by language experience. We investigated whether early, pre-attentive stages of pitch processing at the level of the human brainstem may also be influenced by language experience. The human frequency following response (FFR), reflecting sustained phase-locked activity in a population of neural elements, was used to measure activity within the rostral brainstem. FFRs elicited by four Mandarin tones were recorded from native speakers of Mandarin Chinese and English. Pitch strength (reflecting robustness of neural phase-locking at the pitch periods) and accuracy of pitch tracking were extracted from the FFRs using autocorrelation algorithms. These measures revealed that the Chinese group exhibits stronger pitch representation and smoother pitch tracking than the English group. Consistent with the pitch data, FFR spectral data showed that the Chinese group exhibits stronger representation of the second harmonic relative to the English group across all four tones. These results cannot be explained by a temporal pitch encoding scheme which simply extracts the dominant interspike interval. Rather, these results support the possibility of neural plasticity at the brainstem level that is induced by language experience that may be enhancing or priming linguistically relevant features of the speech input.
大脑皮层水平上音高感知的神经过程受语言经验影响。我们研究了人类脑干水平上音高处理的早期、前注意阶段是否也受语言经验影响。人类频率跟随反应（FFR）反映了一群神经元中的持续锁相活动，用于测量延髓脑干内的活动。从汉语普通话和英语的母语者中记录了由四种汉语声调引发的FFR。使用自相关算法从FFR中提取音高强度（反映音高周期内神经锁相的稳健性）和音高跟踪的准确性。这些测量结果显示，汉语组比英语组表现出更强的音高表征和更平滑的音高跟踪。与音高数据一致，FFR频谱数据显示，在所有四种声调中，汉语组相对于英语组表现出更强的二次谐波表征。这些结果不能用简单提取主要峰峰间隔的时间音高编码方案来解释。相反，这些结果支持了脑干水平上神经可塑性的可能性，这种可塑性是由语言经验诱导的，可能会增强或启动语音输入中与语言相关的特征。
