Department of Psychology, Centre for Neuroscience in Education, University of Cambridge, Downing Street, Cambridge CB2 3 EB, United Kingdom.
Laboratoire des Systèmes Perceptifs, UMR 8248, CNRS, France; Ecole Normale Supérieure, PSL University, France; Department of Mechanical, Trinity Centre for Biomedical Engineering and Trinity Institute of Neuroscience, Manufacturing and Biomedical Engineering, Trinity College, The University of Dublin, Ireland; School of Electrical and Electronic Engineering and UCD Centre for Biomedical Engineering, University College Dublin, Ireland.
Neuroimage. 2022 Feb 15;247:118698. doi: 10.1016/j.neuroimage.2021.118698. Epub 2021 Nov 16.
The amplitude envelope of speech carries crucial low-frequency acoustic information that assists linguistic decoding at multiple time scales. Neurophysiological signals are known to track the amplitude envelope of adult-directed speech (ADS), particularly in the theta-band. Acoustic analysis of infant-directed speech (IDS) has revealed significantly greater modulation energy than ADS in an amplitude-modulation (AM) band centred on ∼2 Hz. Accordingly, cortical tracking of IDS by delta-band neural signals may be key to language acquisition. Speech also contains acoustic information within its higher-frequency bands (beta, gamma). Adult EEG and MEG studies reveal an oscillatory hierarchy, whereby low-frequency (delta, theta) neural phase dynamics temporally organize the amplitude of high-frequency signals (phase amplitude coupling, PAC). Whilst consensus is growing around the role of PAC in the matured adult brain, its role in the development of speech processing is unexplored. Here, we examined the presence and maturation of low-frequency (<12 Hz) cortical speech tracking in infants by recording EEG longitudinally from 60 participants when aged 4-, 7- and 11- months as they listened to nursery rhymes. After establishing stimulus-related neural signals in delta and theta, cortical tracking at each age was assessed in the delta, theta and alpha [control] bands using a multivariate temporal response function (mTRF) method. Delta-beta, delta-gamma, theta-beta and theta-gamma phase-amplitude coupling (PAC) was also assessed. Significant delta and theta but not alpha tracking was found. Significant PAC was present at all ages, with both delta and theta -driven coupling observed.
语音的幅度包络携带关键的低频声学信息，可在多个时间尺度上辅助语言解码。已知神经生理信号可跟踪成人指导语音（ADS）的幅度包络，特别是在 theta 频段。对婴儿指导语音（IDS）的声学分析表明，其幅度调制（AM）频段的调制能量明显大于 ADS，中心频率约为 2 Hz。因此，皮质中 delta 波段神经信号对 IDS 的跟踪可能是语言习得的关键。语音还包含其高频频带（β、γ）内的声学信息。成人 EEG 和 MEG 研究揭示了一种振荡层次结构，其中低频（δ、θ）神经相位动力学在高频信号的幅度上进行时间组织（相位幅度耦合，PAC）。虽然关于 PAC 在成熟成年大脑中的作用的共识正在增加，但它在言语处理发展中的作用尚未得到探索。在这里，我们通过在 4、7 和 11 个月大的婴儿听童谣时从 60 名参与者那里长期记录 EEG，来检查低频（<12 Hz）皮质语音跟踪在婴儿中的存在和成熟情况。在 delta 和 theta 中建立与刺激相关的神经信号后，使用多变量时间响应函数（mTRF）方法在 delta、theta 和 alpha [对照]频段评估每个年龄段的皮质跟踪。还评估了 delta-beta、delta-gamma、theta-beta 和 theta-gamma 相位-幅度耦合（PAC）。发现 delta 和 theta 存在显著跟踪，而 alpha 不存在。所有年龄段均存在显著的 PAC，观察到 delta 和 theta 驱动的耦合。
