Sensitivity to temporal modulation rate and spectral bandwidth in the human auditory system: MEG evidence.
Sensitivity to temporal modulation rate and spectral bandwidth in the human auditory system: MEG evidence.
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DOI：
10.1152/jn.00310.2011
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发表时间：
2012
影响因子：
2.5
通讯作者：
Yadong Wang;N. Ding;N. Ahmar;Juanjuan Xiang;D. Poeppel;J. Simon
中科院分区：
文献类型：
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作者：
Yadong Wang;N. Ding;N. Ahmar;Juanjuan Xiang;D. Poeppel;J. Simon
带宽不同的20赫兹以下的慢声调制是语音和许多其他自然声音的主要成分。然而，这些调制的动态神经表示很难通过非侵入性神经记录方法来研究，因为整个大脑都存在缓慢的神经振荡的背景。我们用脑磁图记录了14名受试者对慢幅度调制(AM)的听觉稳态反应(ASSR)。研究了5种AM频率(1.5、3.5、7.5、15.5和31.5赫兹)和4种类型的载波(纯音和1/3、2和5倍频程粉色噪声)的反应。在所有条件下都能可靠地检测到锁相ASSR。响应功率一般随调制速率的增加而降低，除最高速率外，所有速率的响应延迟都在100到150毫秒之间。响应特性仅弱地依赖于带宽。对复值ASSR磁场的傅里叶域分析揭示了几个具有不同响应相位的神经源。当用单个等效电流偶极子(ECD)近似时，ASSR的这些神经源与N1M反应的ECD位置不同，并且位于ECD位置的中间。这些结果表明，人类听觉皮质的全局同步活动被锁相在30赫兹以下的慢时间调制中，神经敏感度随着AM率的增加而降低，对带宽相对不敏感。
Slow acoustic modulations below 20 Hz, of varying bandwidths, are dominant components of speech and many other natural sounds. The dynamic neural representations of these modulations are difficult to study through noninvasive neural-recording methods, however, because of the omnipresent background of slow neural oscillations throughout the brain. We recorded the auditory steady-state responses (aSSR) to slow amplitude modulations (AM) from 14 human subjects using magnetoencephalography. The responses to five AM rates (1.5, 3.5, 7.5, 15.5, and 31.5 Hz) and four types of carrier (pure tone and 1/3-, 2-, and 5-octave pink noise) were investigated. The phase-locked aSSR was detected reliably in all conditions. The response power generally decreases with increasing modulation rate, and the response latency is between 100 and 150 ms for all but the highest rates. Response properties depend only weakly on the bandwidth. Analysis of the complex-valued aSSR magnetic fields in the Fourier domain reveals several neural sources with different response phases. These neural sources of the aSSR, when approximated by a single equivalent current dipole (ECD), are distinct from and medial to the ECD location of the N1m response. These results demonstrate that the globally synchronized activity in the human auditory cortex is phase locked to slow temporal modulations below 30 Hz, and the neural sensitivity decreases with an increasing AM rate, with relative insensitivity to bandwidth.