θ频段(4~8Hz)的活动反映了汉语口语产生中音节信息的加工

Theta band(4~8Hz)oscillations reflect syllables processing in Chinese spoken word production

大脑的神经振荡往往反映了人类的各种认知活动。语言理解的研究发现大脑θ频段的活动与音节的加工密切相关,但目前尚未有研究者探究语言产生过程中大脑特定频段活动与音节加工的联系。我们通过EEG时频分析技术,采用掩蔽启动范式,考察了23名健康被试在图片命名过程中θ频段的活动与音节加工过程的关系。行为结果发现,当启动词和目标图名称之间存在音节相关时,个体的命名反应时快于音节无关的条件,而音素相关条件的命名反应时慢于音素无关条件。时频结果发现,在刺激出现后的270~460ms,音节相关条件下个体θ频段神经振荡的能量显著低于音节无关条件,音素相关与音素无关之间无显著差异。综上,我们认为汉语口语产生中大脑θ频段的活动反映了对音节的加工,从神经振荡指标上为音节是汉语口语词汇产生中音韵编码的单元提供了证据。

Languages may differ in the proximate units of phonological encoding in spoken word production.It has been demonstrated that syllables are proximate units of phonological encoding in Chinese speech production.Previous studies report that theθband oscillations has been associated with syllables processing in language comprehension,however,it remains unknown what are the neural oscillations for syllables retrieval in speech production.The present study aims to investigate the neural oscillations of syllables retrieval at the stage of phonological encoding in Chinese spoken word production.We employed a masked priming paradigm and electrophysiological signals were recorded concurrently.In the task,participants were instructed to name pictures with disyllabic words which were preceded by briefly presented and masked prime words.Prime words were syllabically or phonemically related to the first syllable of targets or were unrelated,and the experimental design includes prime type(syllable vs.phoneme),relatedness(related vs.unrelated),and repetition(first vs.second).Behavioral data analysis showed a significant triple interaction among prime type,relatedness and repetition.In the first repetition,naming latencies were faster in syllabically related than unrelated condition,whereas latencies were longer in the phonemically related than unrelated condition.Time-frequency analysis also showed a significant interaction between prime type and relatedness in the time window of 300-600 ms after pictures onset.Specifically,theta band power was lower for syllabically related than unrelated while no significant differences between phonemically related and unrelated.Cluster based permutation test showed that,in the first repetition,syllabically related condition elicited lowerθband power than unrelated in the time window of 270-460 ms,while phoneme relatedness produced marginally higherθband power than phoneme unrelatedness in the 340-390 ms time window.These effects were absent in the second repetition.In sum,we found that syllable priming effect was reflected by the decrease ofθoscillation in spoken word production in Chinese.Time-frequency analysis also revealed an early syllable priming effect,and a late phonemic inhibition effect in Chinese spoken word production,which provides evidence for the proximate units principle.