新生儿语音感知的神经基础:元分析
深圳大学心理学院, 深圳 518060
The brain mechanism of speech perception in newborns: A meta-analysis
College of Psychology, Shenzhen University, Shenzhen 518060, China
通讯作者: 张丹丹, E-mail:zhangdd05@gmail.com
并列第一作者:陈钰, 莫李澄。
收稿日期: 2020-04-22 网络出版日期: 2020-08-15
基金资助: |
|
Received: 2020-04-22 Online: 2020-08-15
语言习得能力是人类在进化中获得的重要能力之一。语言认知的核心功能是语音加工, 因此, 语音加工的脑机制是认知心理学研究的重要课题。我们采用元分析方法, 对使用近红外技术考察新生儿语音感知的结构检测、偏差检测和母语感知的研究进行系统的定量分析, 探究新生儿的典型语音感知脑机制以及这三类语音加工相关脑区的异同。结果显示, 左侧额下回是新生儿检测语音结构的关键脑区; 双侧颞叶在新生儿语音偏差刺激检测中发挥关键作用; 新生儿的母语语音加工存在左侧化优势。
关键词:
Speech processing is the core function of language cognition, and the brain mechanism of speech processing are an important topic in linguistics and cognitive psychology. However, it is unclear that how the newborn's brain perceives speech. The purpose of this review is to investigate the brain mechanism of speech perception in newborns. We found that human beings have a relatively well-developed speech processing mechanism during the neonatal period. While the left frontal lobe (especially the inferior frontal gyrus) plays an important role in detecting speech structure, the bilateral temporal lobes are responsible for detecting speech deviation. In addition, the left hemisphere has an advantage in mother tongue perception.
Keywords:
本文引用格式
陈钰, 莫李澄, 毕蓉, 张丹丹.
CHEN Yu, MO Licheng, BI Rong, ZHANG Dandan.
1 引言
语言是人类沟通的主要方式, 是最重要的交际工具。语言是一种用来交流思想的符号系统, 是音义的结合体(祁志强, 彭聃龄, 2010)。语音是语言的物质载体, 由人的发音器官产生, 其物理属性主要包括音长、音色、音高、音强, 即语音的四要素。音节是构成语音的基本单位, 包括两个语音成分:音段(如元音、辅音)和超音段(如重音、声调) (Wenrich, Davidson, & Uchanski, 2017)。
语音是语言符号系统的重要载体, 语言依靠语音实现它的社会功能。通常情况下, 人们需要先学会正确地感知语音、掌握发音, 才能建立起音与义的联结, 进而使用语音向其他人传达意义。从这个意义上来说, 语音加工是语言认知的核心(祁志强, 彭聃龄, 2010)。关于人类的大脑是如何加工和处理语音这个问题, 先前已有大量研究对成人、儿童以及婴儿语音加工的脑机制进行探讨(Planton et al., 2019; Bhat, Palaniswamy, Pichaimuthu, & Thomas, 2018; von Holzen, Nishibayashi, & Nazzi, 2018)。相比之下, 关注新生儿语音加工的研究则较少(注:胎儿自娩出起到出生后28天, 被称为“新生儿”)。语音加工包括语音感知和语音输出两个方面, 新生儿仅能接收语音, 也就是语音感知, 因此本文的目的是探讨新生儿语音感知的神经基础。具体来讲, 我们将从以下三个方面考察新生儿的语音感知。
第一, 人类在加工语言结构时存在知觉偏好, 对语音序列的特殊位置以及有特殊结构的语音序列非常敏感。例如, 一项成人语言记忆研究发现, 被试对序列中第一项和最后一项的记忆成绩优于对中间项的记忆, 即序列位置效应(Schroeder & Rembrandt, 2018)。另一项行为实验发现7个月大的婴儿已存在该效应:让婴儿先熟悉一个多音节序列后, 交换中间音节, 保留边缘音节, 婴儿仍然将改变过的序列识别为听过的序列; 相反, 交换首末音节后婴儿会将序列识别为新序列(Benavides- Varela & Mehler, 2015)。本文将这类对比考察语音特殊结构和一般结构的研究称为结构检测研究, 并对该类研究在新生儿阶段的成果进行元分析。
第二, 已知重复刺激序列中突然出现的新异刺激会在成人和儿童的脑皮层诱发出失匹配负波(mismatch negativity, MMN), 该事件相关电位成分是听觉研究中的常用指标, 代表大脑对新、旧两种声音刺激之间差异的识别(Saarikivi, Putkinen, Tervaniemi, & Huotilainen, 2016; Marklund, Lacerda, & Schwarz, 2018)。本文将这类研究称为偏差检测研究, 其中重复出现的刺激称为标准刺激, 突然出现的新异刺激称为偏差刺激。进一步地, 我们对新生儿在音段特征以及超音段特征的偏差检测研究进行元分析, 以探讨其关键脑区。其中音段特征包括辅音、元音等(Wenrich et al., 2017), 对音段特征的感知可以看作是对“说话内容”进行感知; 超音段特征是指超越音段的语音特征, 例如重音、声调、语调、谐律等的变化。对超音段特征的感知可以看作是对“说话方式”及“说话人”的感知。
第三, 已有研究表明人们对母语比对非母语更加敏感, 在母语加工中存在明显的大脑左侧优势效应。例如, 采用脑电技术, Peña, Pittaluga和Mehler (2010)发现婴儿在母语条件下, 大脑表现出更强的gama频段能量。Paquette等人(2015)使用功能近红外成像技术(functional near-infrared spectroscopy, fNIRS)发现, 成人、青少年以及儿童使用母语表达时, 大脑左半球的激活均显著强于右半球。在尚未具备表达能力的婴儿中也存在这种母语左侧优势。Minagawa-Kawai等人(2011)的研究表明, 4月龄的婴儿在收听母语时左侧颞叶显著激活, 而右侧颞叶则无明显反应。另有研究发现尚处于语言学习最初始阶段的新生儿也表现出对母语的偏好与敏感。一项行为实验发现当新生儿听到母语时, 他们的吮吸频率明显增高(Moon, Cooper, & Fifer, 1993)。但关于新生儿是否已存在母语的左半球优势效应尚不清楚, 针对这一问题, 我们对已有相关研究进行了元分析。
由于新生儿群体的特殊性, 新生儿语音感知方面的研究大多采用近红外成像技术。fNIRS是近年来发展起来的一种光学神经成像技术, 它是在近红外光谱范围内(70~1100 nm)通过对含氧血红蛋白(HbO2)、脱氧血红蛋白(HbR)、总血红蛋白(HbT)等指标的监测, 反映大脑组织氧代谢功能的非创伤性技术(高晋健, 唐文渊, 1996; Paquette et al., 2015)。fNIRS可以监测许多不同的组织和器官, 并以其安全、无创性、较高的高空间分辨率、较小运动伪影以及低环境要求的优点在新生儿研究领域得到了广泛的应用(de Roever et al., 2016; Zhang, Chen, Hou, & Wu, 2019)。近年来, 许多研究者采用fNIRS技术考察新生儿语音感知的大脑激活, 试图阐明语音感知的神经机制。在此背景下, 我们对测量新生儿语音感知的fNIRS研究进行了系统回顾, 以期帮助我们更全面地了解新生儿语音感知的脑机制。本研究从以往的研究中提取出了上述三个最主要的语音感知相关变量(结构检测、偏差检测、母语感知), 并试图寻找这三个变量的特异性脑区。
2 材料与方法
2.1 纳入标准
文献检索涵盖了中文和英文文献, 检索截止日期为2019年10月31日。中文文献检索使用中国知网数据库(CNKI), 基于本文的主题选择了检索关键词, 即和“新生儿”以及“语音”相近或相关的中英文词汇:[“语言” OR “语音” OR “母语” OR “外语” OR “元音” OR “辅音” OR “音节” OR “音位” OR “音素”] AND "新生儿”; 英文文献检索使用 PubMed和ISI Web 数据库, 检索关键词为:[“language” OR “speech ” OR “ speech sound” OR “mother tongue” OR “native language” OR “native tongue” OR “foreign language” OR “non-native language” OR “syllable” OR “vowel” OR “consonant” OR “phoneme”] AND [“newborn” OR “neonate” OR “young infant”]。进一步地, 我们还对检索出的文献中的参考文献(即二次文献)进行了筛选。所有入选文献需同时符合以下标准:(1) 被试为健康新生儿(出生年龄为0~28天), 年龄大于28天的婴儿不纳入本次元分析; (2) 以语音刺激为实验材料并采用fNIRS技术测量大脑活动; (3) 报告脑区激活结果。文献筛选流程如图1所示。最终纳 入本研究的13篇fNIRS英文文献, 均为期刊论文,其中包含“结构检测”对比条件(contrast)的有5篇(表1), 包含“偏差检测”对比条件的有5篇(表2), 包含“母语感知”对比条件的有3篇(表3)。
图1
表1 语音结构检测文献列表
文献 | N | 对比条件(contrast) | 主要激活位置 | 效应量 |
---|---|---|---|---|
Ferry et al., 2016 | 32 | 特殊结构 > 一般结构 | 双侧颞-额 | 0.66 |
Gervain et al., 2008 | 22 | 特殊结构 > 一般结构 | 双侧颞-额(左额激活最大) | 0.33 |
Gervain et al., 2012 | 22 | 特殊结构 > 一般结构 | 双侧颞-额 | 0.34 |
Gervain et al., 2012 | 20 | 特殊结构 > 一般结构 | 双侧颞-额(左额激活最大) | 0.37 |
Gómez et al., 2014 | 24 | 特殊结构 > 一般结构 | 双侧颞-额 | 0.39 |
Gómez et al., 2014 | 24 | 特殊结构 > 一般结构 | 双侧颞-额 | 0.41 |
Kudo et al., 2011 | 18 | 特殊结构 > 一般结构 | 双侧颞-额(左额激活最大) | 0.54 |
表2 语音偏差刺激检测文献列表
文献 | N | 对比条件(contrast) | 主要激活位置 | 效应量 |
---|---|---|---|---|
Arimitsu et al., 2011 | 14 | 偏差刺激 > 标准刺激 | 双颞 | 0.47 |
Carlier-Torres et al., 2014 | 13 | 偏差刺激 > 标准刺激 | 双颞 | 0.51 |
Carlier-Torres et al., 2014 | 13 | 偏差刺激 > 标准刺激 | 双颞 | 0.62 |
Mahmoudzadeh et al., 2013 | 6 | 偏差刺激 > 标准刺激 | 双颞 | 1.03 |
Mahmoudzadeh et al., 2017 | 19 | 偏差刺激 > 标准刺激 | 双颞 | 0.44 |
Sambeth, 2009 | 10 | 偏差刺激 > 标准刺激 | 双颞 | 0.87 |
表3 母语感知文献列表
文献 | N | 对比条件(contrast) | 主要激活位置 | 效应量 |
---|---|---|---|---|
Peña et al., 2003 | 12 | 左颞 > 右颞 | 左颞 | 0.65 |
Sato et al., 2012 | 17 | 左颞 > 右颞 | 左颞 | 0.28 |
Vannasing et al., 2016 | 27 | 左颞 > 右颞 | 左颞 | 2.73 |
2.2 统计分析
fNIRS的测量指标包括HbO2, HbR和HbT (Ferrari & Quaresima, 2012)。但通过文献回顾, 我们发现大多数文章并没有报告HbR和HbT的变化, 仅报告和讨论了HbO2的变化。此外, HbO2也被认为是fNIRS测量中对神经反应-脑血流耦合最敏感的指标(Saito et al., 2007), 因此, 本研究采用HbO2作为反映新生儿大脑活动的指标。
由于fNIRS技术的进步以及不同公司产品的差异, 各项研究中使用的fNIRS仪器型号不一而足。在HbO2平均值变化的统计分析中, 本研究的一个难点来自fNIRS装置的通道数目和覆盖脑区在不同文献中的差异性。针对这个难题, 本研究利用新生儿脑模, 基于fNIRS通道定位与大脑脑区的对应关系, 将新生儿脑区大致划分为左侧额叶、右侧额叶、左侧颞叶、右侧颞叶, 并提取分别覆盖这4个脑区的通道信号进行数据分析。本研究使用Revman 5.3软件(Chen, Sun, Ma, Yin, & Liang, 2019; Zhang et al., 2015)进行分析, 选用Fisher’s Z转换法计算效应值(郑凤英, 彭少麟, 2001)。效应值是定量元分析中的结合统计量, 其计算方法主要依赖于对原文献数据的获取程度。由于本研究中的大部分文献没有提供原始数据(如HbO2的平均值、标准差以及样本量), 仅报告了统计检验的F值和t值, 因此我们将F值或t值转化为相关系数, 再用Fisher’s Z转换计算效应值(郑凤英, 彭少麟, 2001; 注:Z的大小范围在-∞和+∞之间, 负值代表负效应, 正值代表正效应, 等于0时无效应)。本文的元分析主要分为以下三个步骤:首先检索相关文献并按照结构检测、偏差检测、母语感知这三个研究方向进行分类; 然后提取每篇文献的关键统计数据即F值或 t值, 先将其转化为相关系数, 再用Fisher's Z转换计算出每个研究的效应值; 最后使用Revman 5.3软件进行逆方差(inverse variance)元分析, 算出每个变量的合并效应值, 并对结果进行解释和讨论。
3 结果
3.1 结构检测激活的脑区
Ferry等人(2016)使用fNIRS技术发现在新生儿阶段就已存在语音感知的序列位置效应。让新生儿熟悉一个六音节的语音序列后, 交换首尾音节比交换中间音节激活了更强的颞叶和额叶活动。这是由于当交换首尾音节时, 新生儿将该序列识别为新序列, 而交换中间音节时, 新生儿仍将其识别为已熟悉的旧序列, 本实验表明新生儿对首尾音节的编码比中间音节更准确。Gervain等人(2008)的fNIRS研究发现, 新生儿对语音序列的重复结构也非常敏感:当听到重复序列(如/mubaba/, ABB)时, 与听到非重复结构相比(如/mubapo/, ABC), 新生儿的左侧额叶(尤其是额下回)的血流动力学反应显著增强, 这表明左侧额下回对重复结构敏感。Gervain等人(2012)在后续研究中还发现, 除了能检测到重复结构, 新生儿还可以检测到重复音节的位置:让新生儿分别听非交替条件(ABB和AAB在不同block中呈现)和交替条件(ABB和AAB在同一block中交替出现)的音节序列, 发现在非交替条件下, 左侧额下回以及双侧颞叶激活更强, 表明新生儿在该条件下能够找到音节的结构规律, 提取出音节重复的位置, 即新生儿可以区分ABB和AAB结构。
在此基础上, 我们对考察新生儿语音结构检测的7项研究进行了元分析, 揭示对特殊结构比对一般结构的激活更强的脑区。HbO2的合并Fisher’s Z值为0.42 (95%置信区间0.30~0.54, p < 0.00001; 见图2)。结果显示在检测特殊结构时, HbO2浓度显著增强的脑区主要为双侧额-颞叶, 其中激活最强的脑区为左侧额叶(尤其是额下回)。这表明双侧额-颞叶都参与了语音序列结构检测, 其中左侧额下回的作用最为突出。
图2
图2
使用fNIRS比较新生儿在检测语音序列结构时HbO2浓度的平均变化(contrast:特殊结构减一般结构)。Fisher’s Z, 效应值; CI, 置信区间。
3.2 偏差检测激活的脑区
有研究发现新生儿可以对语音的音段特征(如:元音、辅音)和超音段特征(如:重音、声调、语调等)进行感知(Wenrich et al., 2017), 并且可以进行偏差检测, 诱发出类似于成人失匹配负波MMN的脑电成分——失匹配负反应(mismatch response, MMR)。在一项偏差检测研究中, Sambeth等人(2009)同时利用脑电图和脑磁图技术发现, 重复语音刺激序列中出现的以频率和声强改变为特征的新异刺激, 能在新生儿大脑的双侧颞叶诱发脑电成分MMR和对应的脑磁成分MMRm。Mahmoudzadeh等人(2013)利用fNIRS研究发现, 29周胎龄的早产儿其左侧额叶能感知辅音的改变(/ba/ vs. /ga/), 但对音色的改变(男vs.女)不敏感。Mahmoudzadeh等人(2017)的后续研究采用4个相同音节组成标准刺激(如/babababa/), 改变第4个音节的辅音构成偏差刺激(如/bababaga/), 发现偏差刺激在足月新生儿大脑的额叶和颞叶诱发了MMR, 且左侧额-颞叶的MMR比右侧的MMR潜伏期更早。此外, Partanen, Pakarinen, Kujala和Huotilainen (2013)发现辅音和元音的改变可在新生儿大脑中诱发出显著的MMR, 且在中央区和额区幅度最大; 同样地, 元音的持续时间和辅音强度的改变能产生显著的MMR。在另一项类似的脑磁图研究中, Kujala等人(2004)发现, 重复播放的元音/a:/中突然出现的元音/i:/, 或是音高稳定的元音/a:/中偶尔播放音高上升的/a:/, 均能在新生儿大脑中诱发出MMNm。这些研究表明新生儿可以对语音的音段特征和超音段特征进行偏差检测, 区分标准刺激和偏差刺激。
在此基础上, 我们对考察新生儿语音偏差检测的6项研究进行了元分析, 揭示对偏差刺激比对标准刺激的激活更强的脑区。HbO2的合并Fisher’s Z值为0.59 (95%置信区间0.42~0.76, p < 0.00001; 见图3)。结果显示新生儿在检测偏差刺激时, HbO2浓度显著增加的脑区为双侧颞叶(主要是颞上回)。这表明双侧颞上回在新生儿的语音偏差检测中发挥着关键作用。
图3
图3
使用fNIRS比较新生儿在检测语音偏差刺激时HbO2浓度的平均变化(contrast:偏差刺激减标准刺激)。Fisher’s Z, 效应值; CI, 置信区间。
3.3 母语感知激活的脑区
Peña等人(2003)使用fNIRS技术发现, 新生儿在听母语时其左侧颞叶的血流动力学反应明显大于右侧颞叶。Sato等人(2012)的研究也发现, 相比非母语(英语), 日本的新生儿听到日语时左侧颞叶激活更强。此外, 近期一项fNIRS研究发现(Vannasing et al., 2016), 在听到母语时新生儿的左侧颞叶激活显著而右侧没有明显反应。
在此基础上, 我们对考察新生儿母语感知的3项研究进行了元分析, 对新生儿是否存在母语加工的左半球优势进行了验证。HbO2的合并Fisher’s Z值为1.57 (95%置信区间1.38~1.77, p < 0.00001; 见图4)。结果显示, 新生儿在加工母语时, 大脑左半球的HbO2浓度增加显著高于右半球, 主要激活脑区在左侧颞叶。这表明新生儿的母语语音加工存在左侧化优势。
图4
图4
使用fNIRS比较新生儿在感知母语语音刺激时HbO2浓度的平均变化(contrast:左半球减右半球)。Fisher’s Z, 效应值; CI, 置信区间。
4 讨论
4.1 结构检测
通过对新生儿大脑在结构检测已有研究成果的元分析, 我们发现新生儿可以检测到音节序列结构, 例如对首尾位置音节的编码比对中间音节的编码更准确, 可以检测到重复音节及重复的位置。新生儿在检测语音结构时激活最显著的脑区是左侧额下回。该脑区在成人和儿童中称为Broca区, 负责短语、句子整合以及序列学习(Alamia et al., 2016; Uddén, Ingvar, Hagoort, & Petersson, 2017)。而新生儿对语音结构进行检测时也离不开音素、音节的整合以及序列的学习。因此左侧额下回激活显著的结果与成人以及儿童一致, 提示了Broca区神经机制发育的连续性。
4.2 偏差检测
通过对新生儿大脑在偏差检测已有研究成果的元分析, 我们发现新生儿大脑可以检测到语音的音段特征和超音段特征的细微改变, 即偏差检测, 并诱发出MMR脑电成分。新生儿在检测偏差刺激时显著激活了双侧颞叶(尤其是颞上回), 与双侧颞上回在语音判断和语音-音高比较任务中发挥关键作用的结论一致(Paquette et al., 2015)。颞上回负责音位知觉(Binder, 2017)以及右侧颞上回负责韵律加工(Vannasing et al., 2016; Zhang et al., 2019)的结论也分别验证了颞上回在在检测音段特征和超音段特征中的关键作用。我们发现, 新生儿在偏差检测中并未表现出语言的左半球优势, 这可能是因为偏差检测包括对超音段特征例如声调、韵律等的感知。而右侧颞叶被看作是加工韵律的特定脑区。Telkemeyer等人(2009)在新生儿中发现, 右半球主要参与慢速声学变化的加工, 如音高、韵律等。另一项fNIRS研究发现1~2日龄的新生儿在听音乐时双侧大脑激活, 也表明了右半球在韵律加工方面的重要作用(Kotilahti et al., 2010)。因此, 新生儿在进行偏差检测时, 可能不仅语言加工的左半球优势区得到了激活, 负责加工韵律的右侧颞叶也同时激活了(Vannasing et al., 2016)。
4.3 母语感知
通过对新生儿大脑母语感知方面已有研究成果的元分析, 我们发现新生儿在听母语时, 大脑左半球激活, 支持母语感知的左半球优势理论。新生儿的这一左半球优势可能是由于在胎儿时期不可避免的暴露在母语环境中并对母语进行了初步的编码、学习以及记忆, 因此母语在出生时就已经能在左半球得到优先处理(Abboub, Nazzi, & Gervain, 2016)。此外, 另两项研究虽然也使用母语材料, 但对语音材料进行了低通滤波, 仅保留了语音中的韵律和节奏, 去除了高频信息(May, Byers-Heinlein, Gervain, & Werker, 2011; Peraniet al., 2011)。这两项研究均观察到了大脑的双侧激活, 而未发现母语的左侧优势效应, 表明新生儿对语音的语调和韵律模式进行加工时, 不再只依赖语言加工的优势脑区——左半球, 同时还需要调用负责韵律加工的右侧颞上回(Vannasing et al., 2016; Zhang et al., 2019)。这一结果也从侧面验证了对母语的左半球优势效应是由于对母语的感知受到了产前经验的影响。
通过对新生儿大脑在结构检测、偏差检测、母语感知三个方面元分析结果的总结, 我们得到关于新生儿语音感知脑机制的以下结论:新生儿有相对完善的语音感知神经系统, 加工语音的脑区主要为额叶(尤其是左侧额下回)、颞叶(尤其是颞上回), 其中左侧额下回在检测语音结构中发挥关键作用, 而颞上回在检测偏差刺激中扮演重要角色; 新生儿在母语感知中存在左半球优势。这一结论表明人类在刚出生时即具有了感知语音的基本神经机制, 新生儿对语音特殊结构和偏差刺激高敏感性有助于后续的语言发展, 也证明了从出生时就具备语言习得的神经基础。此外, 新生儿对母语的感知不可避免地受到了产前经验的影响, 这一结果表明了胎教的重要意义, 启发父母在孕期采用良好的教养方式。
4.4 不足和展望
本研究的不足有三点。第一, 纳入本次元分析的文献数量相对较少, 使得我们无法系统全面地考察除了“结构检测”、“偏差检测”和“母语感知”之外的其他变量(例如音段特征和超音段特征)。我们希望随着该领域内实证研究的增加, 未来的元分析能纳入更多的变量从而进一步加深和完善我们对新生儿语音感知脑机制的理解。第二, 由于一些研究报告未提供直接计算效应量所需的原始数据(HbO2的平均值、标准差等), 我们使用F和t值间接计算效应量, 这与使用原始数据计算出的结果可能存在偏差。第三, fNIRS元分析与功能性核磁共振成像(functional magnetic resonance imaging, fMRI)元分析不同, 无法提供激活脑区的精确坐标值。此外, 由于各项研究所使用的fNIRS装置的通道数目和覆盖脑区不同, 本文将脑区粗略地划分为左侧额叶、右侧额叶、左侧颞叶以及右侧颞叶, 这使得我们无法将新生儿语音加工的相关脑区定位到更精确的沟回上。
我们建议未来在新生儿语音感知的神经机制研究从以下几个方面继续探索。首先, 已有的研究大多仅关注单一时间节点, 未考察新生儿出生一段时间后通过接触和学习语音刺激导致的大脑改变。目前仅有一项ERP研究考察了新生儿通过2.5~5个小时的语音学习, 其大脑对所学习音节的MMR较学习之前发生了改变, 表明即使是经过短暂的学习, 新生儿脑功能也会发生显著改变(Cheour et al., 2002)。后续研究可以借鉴该模式, 考察新生儿出生即刻(宫外学习前)、语音刺激学习后即刻, 以及学习后数小时、数天、数周的神经活动改变, 揭示新生儿大脑对语音学习的超强可塑性。另一个思路是考察新生儿出生后(新生儿期)、3月龄(小婴儿期)、6~12月龄(大婴儿期)、1~3岁(幼儿期)大脑语音感知神经基础的发展和变化, 在已有行为学研究基础上, 精确标定人类早期语言发展的神经机制时间节点, 为科学育儿提供神经学证据。最后, 通过本文的元分析我们发现, 目前研究结果揭示的部分关键脑区并不一致, 这可能是由于已有研究大多并未严格操纵任务(偏差检测、结构检测)和语言种类(母语、外语)的不同水平。例如, 母语的偏差检测研究中, 起作用的关键脑区功能到底应解释为母语感知还是偏差检测, 亦或二者兼而有之?后续研究需要使用更加规范的正交化实验设计, 考察不同变量的各自效应和变量间的交互效应。
5 结论
本文对现有新生儿语音感知的fNIRS研究进行了基于结构检测、偏差检测和母语感知变量的单因素元分析。结果发现, 人类在新生儿时期就已存在相对完善的语音感知机制:(1)左侧额叶(尤其是额下回)是新生儿检测语音结构的关键脑区; (2)双侧颞叶在新生儿语音偏差刺激检测中发挥关键作用; (3)新生儿的母语语音加工存在左侧化优势。
参考文献
Prosodic grouping at birth
DOI:10.1016/j.bandl.2016.08.002
URL
PMID:27567401
[本文引用: 1]
Experience with spoken language starts prenatally, as hearing becomes operational during the second half of gestation. While maternal tissues filter out many aspects of speech, they readily transmit speech prosody and rhythm. These properties of the speech signal then play a central role in early language acquisition. In this study, we ask how the newborn brain uses variation in duration, pitch and intensity (the three acoustic cues that carry prosodic information in speech) to group sounds. In four near-infrared spectroscopy studies (NIRS), we demonstrate that perceptual biases governing how sound sequences are perceived and organized are present in newborns from monolingual and bilingual language backgrounds. Importantly, however, these prosodic biases are present only for acoustic patterns found in the prosody of their native languages. These findings advance our understanding of how prenatal language experience lays the foundations for language development.
Disruption of Broca's area alters higher-order chunking processing during perceptual sequence learning
DOI:10.1162/jocn_a_00911
URL
PMID:26765778
[本文引用: 1]
Because Broca's area is known to be involved in many cognitive functions, including language, music, and action processing, several attempts have been made to propose a unifying theory of its role that emphasizes a possible contribution to syntactic processing. Recently, we have postulated that Broca's area might be involved in higher-order chunk processing during implicit learning of a motor sequence. Chunking is an information-processing mechanism that consists of grouping consecutive items in a sequence and is likely to be involved in all of the aforementioned cognitive processes. Demonstrating a contribution of Broca's area to chunking during the learning of a nonmotor sequence that does not involve language could shed new light on its function. To address this issue, we used offline MRI-guided TMS in healthy volunteers to disrupt the activity of either the posterior part of Broca's area (left Brodmann's area [BA] 44) or a control site just before participants learned a perceptual sequence structured in distinct hierarchical levels. We found that disruption of the left BA 44 increased the processing time of stimuli representing the boundaries of higher-order chunks and modified the chunking strategy. The current results highlight the possible role of the left BA 44 in building up effector-independent representations of higher-order events in structured sequences. This might clarify the contribution of Broca's area in processing hierarchical structures, a key mechanism in many cognitive functions, such as language and composite actions.
Functional hemispheric specialization in processing phonemic and prosodic auditory changes in neonates
Verbal positional memory in 7-month-olds
Cortical auditory evoked potentials and hemispheric specialization of speech in individuals with learning disability and healthy controls: A preliminary study
Current controversies on Wernicke's area and its role in language
The hemodynamic response to acoustically modified syllables in premature and full term newborn infants acquired by near infrared spectroscopy
The wedge insole for the treatment of knee osteoarthritis: A systematic review protocol
Speech sounds learned by sleeping newborns
DOI:10.1038/415599a
URL
PMID:11832929
[本文引用: 1]
Many applications have been found for carbon nanotubes, and we can now add a role as a 'nanothermometer' to this list. We describe how the height of a continuous, unidimensional column of liquid gallium inside a carbon nanotube (up to about 10 micrometres long and about 75 nanometres in diameter) varies linearly and reproducibly in the temperature range 50-500 degrees C, with an expansion coefficient that is the same as for gallium in the macroscopic state. We chose gallium as our thermal indicator because it has one of the greatest liquid ranges of any metal (29.78-2,403 degrees C) and a low vapour pressure even at high temperatures. This nanothermometer should be suitable for use in a wide variety of microenvironments.
Investigation of the pattern of the hemodynamic response as measured by functional near-Infrared spectroscopy (fNIRS) studies in newborns, less than a month old: A systematic review
A brief review on the history of human functional near-infrared spectroscopy (fNIRS) development and fields of application
DOI:10.1016/j.neuroimage.2012.03.049
URL
PMID:22510258
[本文引用: 1]
This review is aimed at celebrating the upcoming 20th anniversary of the birth of human functional near-infrared spectroscopy (fNIRS). After the discovery in 1992 that the functional activation of the human cerebral cortex (due to oxygenation and hemodynamic changes) can be explored by NIRS, human functional brain mapping research has gained a new dimension. fNIRS or optical topography, or near-infrared imaging or diffuse optical imaging is used mainly to detect simultaneous changes in optical properties of the human cortex from multiple measurement sites and displays the results in the form of a map or image over a specific area. In order to place current fNIRS research in its proper context, this paper presents a brief historical overview of the events that have shaped the present status of fNIRS. In particular, technological progresses of fNIRS are highlighted (i.e., from single-site to multi-site functional cortical measurements (images)), introduction of the commercial multi-channel systems, recent commercial wireless instrumentation and more advanced prototypes.
On the edge of language acquisition: Inherent constraints on encoding multisyllabic sequences in the neonate brain
Binding at birth: The newborn brain detects identity relations and sequential position in speech
The neonate brain detects speech structure
Language universals at birth
Hemodynamic responses to speech and music in newborn infants
On-line statistical segmentation of a non-speech auditory stream in neonates as demonstrated by event-related brain potentials
Speech-sound discrimination in neonates as measured with MEG
Syllabic discrimination in premature human infants prior to complete formation of cortical layers
Functional maps at the onset of auditory inputs in very early preterm human neonates
Using rotated speech to approximate the acoustic mismatch negativity response to speech
Language and the newborn brain: does prenatal language experience shape the neonate neural response to speech?
Optical brain imaging reveals general auditory and language-specific processing in early infant development
Two-day-olds prefer their native language
Developmental patterns of expressive language hemispheric lateralization in children, adolescents and adults using functional near-infrared spectroscopy
Infants' brain responses for speech sound changes in fast multifeature MMN paradigm
Sounds and silence: an optical topography study of language recognition at birth
Language acquisition in premature and full-term infants
Neural language networks at birth
Top-down activation of the visuo-orthographic system during spoken sentence processing
Cognitive flexibility modulates maturation and music- training-related changes in neural sound discrimination
The function of the frontal lobe in neonates for response to a prosodic voice
Change detection in newborns using a multiple deviant paradigm: A study using magnetoencephalography
Cerebral hemodynamics in newborn infants exposed to speech sounds: A whole-head optical topography study
DOI:10.1002/hbm.21350
URL
PMID:21714036
[本文引用: 2]
Considerable knowledge on neural development related to speech perception has been obtained by functional imaging studies using near-infrared spectroscopy (optical topography). In particular, a pioneering study showed stronger left-dominant activation in the temporal lobe for (normal) forward speech (FW) than for (reversed) backward speech (BW) in neonates. However, it is unclear whether this stronger left-dominant activation for FW is equally observed for any language or is clearer for the mother tongue. We hypothesized that the maternal language elicits clearer activation than a foreign language in newborns because of their prenatal and/or few-day postnatal exposure to the maternal language. To test this hypothesis, we developed a whole-head optode cap for 72-channel optical topography and visualized the spatiotemporal hemodynamics in the brains of 17 Japanese newborns when they were exposed to FW and BW in their maternal language (Japanese) and in a foreign language (English). Statistical analysis showed that all sound stimuli together induced significant activation in the bilateral temporal regions and the frontal region. They also showed that the left temporal-parietal region was significantly more active for Japanese FW than Japanese BW or English FW, while no significant difference between FW and BW was shown for English. This supports our hypothesis and suggests that the few-day-old brain begins to become attuned to the maternal language. Together with a finding of equivalent activation for all sound stimuli in the adjacent measurement positions in the temporal region, these findings further clarify the functional organization of the neonatal brain.
How effectively do people remember voice disordered speech? An investigation of the serial-position curve
DOI:10.3390/brainsci8120211
URL
PMID:30513678
[本文引用: 1]
Although ageing is known to affect memory, the precise nature of its effect on retrieval and encoding processes is not well understood. Here, we examine the effect of ageing on the free recall of word lists, in which the semantic structure of word sequences was manipulated from unrelated words to pairs of associated words with various separations (between pair members) within the sequence. We find that ageing is associated with reduced total recall, especially for sequences with associated words. Furthermore, we find that the degree of semantic clustering (controlled for chance clustering) shows an age effect and that it interacts with the distance between the words within a pair. The results are consistent with the view that age effects in memory are mediated both by retrieval and by encoding processes associated with frontal control and working memory.
Sensitivity of newborn auditory cortex to the temporal structure of sounds
DOI:10.1523/JNEUROSCI.1246-09.2009
URL
PMID:19940167
[本文引用: 1]
Understanding the rapidly developing building blocks of speech perception in infancy requires a close look at the auditory prerequisites for speech sound processing. Pioneering studies have demonstrated that hemispheric specializations for language processing are already present in early infancy. However, whether these computational asymmetries can be considered a function of linguistic attributes or a consequence of basic temporal signal properties is under debate. Several studies in adults link hemispheric specialization for certain aspects of speech perception to an asymmetry in cortical tuning and reveal that the auditory cortices are differentially sensitive to spectrotemporal features of speech. Applying concurrent electrophysiological (EEG) and hemodynamic (near-infrared spectroscopy) recording to newborn infants listening to temporally structured nonspeech signals, we provide evidence that newborns process nonlinguistic acoustic stimuli that share critical temporal features with language in a differential manner. The newborn brain preferentially processes temporal modulations especially relevant for phoneme perception. In line with multi-time-resolution conceptions, modulations on the time scale of phonemes elicit strong bilateral cortical responses. Our data furthermore suggest that responses to slow acoustic modulations are lateralized to the right hemisphere. That is, the newborn auditory cortex is sensitive to the temporal structure of the auditory input and shows an emerging tendency for functional asymmetry. Hence, our findings support the hypothesis that development of speech perception is linked to basic capacities in auditory processing. From birth, the brain is tuned to critical temporal properties of linguistic signals to facilitate one of the major needs of humans: to communicate.
Broca's region: A causal role in implicit processing of grammars with crossed non-adjacent dependencies
DOI:10.1016/j.cognition.2017.03.010
URL
PMID:28453996
[本文引用: 1]
Non-adjacent dependencies are challenging for the language learning machinery and are acquired later than adjacent dependencies. In this transcranial magnetic stimulation (TMS) study, we show that participants successfully discriminated between grammatical and non-grammatical sequences after having implicitly acquired an artificial language with crossed non-adjacent dependencies. Subsequent to transcranial magnetic stimulation of Broca's region, discrimination was impaired compared to when a language-irrelevant control region (vertex) was stimulated. These results support the view that Broca's region is engaged in structured sequence processing and extend previous functional neuroimaging results on artificial grammar learning (AGL) in two directions: first, the results establish that Broca's region is a causal component in the processing of non-adjacent dependencies, and second, they show that implicit processing of non-adjacent dependencies engages Broca's region. Since patients with lesions in Broca's region do not always show grammatical processing difficulties, the result that Broca's region is causally linked to processing of non-adjacent dependencies is a step towards clarification of the exact nature of syntactic deficits caused by lesions or perturbation to Broca's region. Our findings are consistent with previous results and support a role for Broca's region in general structured sequence processing, rather than a specific role for the processing of hierarchically organized sentence structure.
Distinct hemispheric specializations for native and non-native languages in one-day-old newborns identified by fNIRS
DOI:10.1016/j.neuropsychologia.2016.01.038
URL
PMID:26851309
[本文引用: 4]
This study assessed whether the neonatal brain recruits different neural networks for native and non-native languages at birth. Twenty-seven one-day-old full-term infants underwent functional near-infrared spectroscopy (fNIRS) recording during linguistic and non-linguistic stimulation. Fourteen newborns listened to linguistic stimuli (native and non-native language stories) and 13 newborns were exposed to non-linguistic conditions (native and non-native stimuli played in reverse). Comparisons between left and right hemisphere oxyhemoglobin (HbO2) concentration changes over the temporal areas revealed clear left hemisphere dominance for native language, whereas non-native stimuli were associated with right hemisphere lateralization. In addition, bilateral cerebral activation was found for non-linguistic stimulus processing. Overall, our findings indicate that from the first day after birth, native language and prosodic features are processed in parallel by distinct neural networks.
Consonant and vowel processing in word form segmentation: An infant ERP study
Segmental and suprasegmental perception in children using hearing aids
DOI:10.3766/jaaa.16105
URL
PMID:29130438
[本文引用: 3]
BACKGROUND: Suprasegmental perception (perception of stress, intonation,
Near-infrared spectroscopy reveals neural perception of vocal emotions in human neonates
Near-infrared spectroscopy for examination of prefrontal activation during cognitive tasks in patients with major depressive disorder: A meta- analysis of observational studies
DOI:10.1111/pcn.12209
URL
PMID:24897940
[本文引用: 1]
AIMS: Near-infrared spectroscopy has the potential for aiding the diagnosis of major depressive disorder. The purpose of this study was to systematically review the evidence from observational studies regarding the use of near-infrared spectroscopy in patients with major depressive disorder and to identify the characteristic pattern of prefrontal lobe activity in major depressive disorder. METHODS: medline, PubMed, Cochrane Library and Web of Science databases were searched in December 2013. All case-control studies were included. The quality of evidence was examined using the Newcastle-Ottawa Quality Assessment Scale. The primary outcome measures were the mean oxygenated and deoxygenated hemoglobin alterations of the cerebral cortex during cognitive activation periods. The standard mean difference for the overall pooled effects across the included studies was estimated using random or fixed effect models. The primary outcome measures were included in the meta-analysis. RESULTS: Fourteen studies met the inclusion criteria. Six studies (n = 692 participants) were included in the analysis of the mean oxygenated hemoglobin alterations; the pooled mean standardized difference was -0.74 (95% confidence interval, -0.97 to -0.52), indicating that patients with major depressive disorder were associated with attenuated increase in oxygenated hemoglobin during cognitive activation in the prefrontal regions compared to healthy controls. Five studies (n = 668 participants) were included in the analysis of mean deoxygenated-hemoglobin changes; the pooled standardized mean difference was 0.18 (95% confidence interval, -0.20 to 0.56). CONCLUSIONS: Using near-infrared spectroscopy measurements, we observed that compared to healthy subjects, patients with major depressive disorder had significantly lower prefrontal activation during cognitive tasks.
/
〈 |
|
〉 |
![](../../../richhtml/1671-3710/richHtml_jats1_1/images/1.png)