Suppression of competing speech through entrainment of cortical oscillations
Suppression of competing speech through entrainment of cortical oscillations
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DOI：
10.1152/jn.01026.2012
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发表时间：
2013-06-01
影响因子：
2.5
通讯作者：
Srinivasan, Ramesh
中科院分区：
文献类型：
--
作者：
Horton, Cort;D'Zmura, Michael;Srinivasan, Ramesh
在竞争对手在场的情况下，人们非常善于倾听一位演讲者，但支持这一点的神经机制仍不清楚。最近的研究认为，相对于竞争者来说，听觉系统通过将音节带入(或“锁相”)其声学包络中的节奏结构，从而确保音节在神经元高度兴奋的时期到达，从而提高了语音流的增益。我们假设，这种机制也可以通过确保音节到达神经元兴奋性较低的时期来抑制竞争的语音流。为了测试这一点，我们分析了成人在听两个相互竞争的自然主义语音流之一时记录的高密度脑电。通过计算EEG通道和语音包络之间的互相关，我们发现了对出席语音的声学包络的夹带以及对无人值守语音的包络的较弱但显著的夹带的证据。对数据的独立成分分析(ICA)分解揭示了后部颞叶皮质中的来源，显示出与有人值守和无人值守信封的强烈相关性。关键的是，在这些成分中，当有人照看时，相关性的迹象与无人照看时相反，与假设的基于夹带的抑制机制一致。
People are highly skilled at attending to one speaker in the presence of competitors, but the neural mechanisms supporting this remain unclear. Recent studies have argued that the auditory system enhances the gain of a speech stream relative to competitors by entraining (or "phase-locking") to the rhythmic structure in its acoustic envelope, thus ensuring that syllables arrive during periods of high neuronal excitability. We hypothesized that such a mechanism could also suppress a competing speech stream by ensuring that syllables arrive during periods of low neuronal excitability. To test this, we analyzed high-density EEG recorded from human adults while they attended to one of two competing, naturalistic speech streams. By calculating the cross-correlation between the EEG channels and the speech envelopes, we found evidence of entrainment to the attended speech's acoustic envelope as well as weaker yet significant entrainment to the unattended speech's envelope. An independent component analysis (ICA) decomposition of the data revealed sources in the posterior temporal cortices that displayed robust correlations to both the attended and unattended envelopes. Critically, in these components the signs of the correlations when attended were opposite those when unattended, consistent with the hypothesized entrainment-based suppressive mechanism.