Phase Alignment of Low-Frequency Neural Activity to the Amplitude Envelope of Speech Reflects Evoked Responses to Acoustic Edges, Not Oscillatory Entrainment
| العنوان: | Phase Alignment of Low-Frequency Neural Activity to the Amplitude Envelope of Speech Reflects Evoked Responses to Acoustic Edges, Not Oscillatory Entrainment |
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| المؤلفون: | Yulia Oganian, Katsuaki Kojima, Assaf Breska, Chang Cai, Anne Findlay, Edward Chang, Srikantan Nagarajan |
| المصدر: | The Journal of Neuroscience The Journal of neuroscience : the official journal of the Society for Neuroscience, vol 43, iss 21 |
| بيانات النشر: | Society for Neuroscience, 2023. |
| سنة النشر: | 2023 |
| مصطلحات موضوعية: | Normalization (statistics), neural oscillations, speech, 1.1 Normal biological development and functioning, Acoustics, Phase (waves), Bioengineering, Tracking (particle physics), Medical and Health Sciences, Convolution, Clinical Research, Underpinning research, otorhinolaryngologic diseases, medicine, Humans, Envelope (waves), Auditory Cortex, Physics, MEG, language, Neurology & Neurosurgery, medicine.diagnostic_test, General Neuroscience, Psychology and Cognitive Sciences, Neurosciences, modeling, Magnetoencephalography, Entrainment (biomusicology), Amplitude, Acoustic Stimulation, Neurological, Auditory Perception, Speech Perception, evoked response, Female |
| الوصف: | The amplitude envelope of speech is crucial for accurate comprehension. Considered a key stage in speech processing, the phase of neural activity in the theta-delta bands (1-10 Hz) tracks the phase of the speech amplitude envelope during listening. However, the mechanisms underlying this envelope representation have been heavily debated. A dominant model posits that envelope tracking reflects entrainment of endogenous low-frequency oscillations to the speech envelope. Alternatively, envelope tracking reflects a series of evoked responses to acoustic landmarks within the envelope. It has proven challenging to distinguish these two mechanisms. To address this, we recorded MEG while participants (n= 12, 6 female) listened to natural speech, and compared the neural phase patterns to the predictions of two computational models: an oscillatory entrainment model and a model of evoked responses to peaks in the rate of envelope change. Critically, we also presented speech at slowed rates, where the spectro-temporal predictions of the two models diverge. Our analyses revealed transient theta phase-locking in regular speech, as predicted by both models. However, for slow speech, we found transient theta and delta phase-locking, a pattern that was fully compatible with the evoked response model but could not be explained by the oscillatory entrainment model. Furthermore, encoding of acoustic edge magnitudes was invariant to contextual speech rate, demonstrating speech rate normalization of acoustic edge representations. Together, our results suggest that neural phase-locking to the speech envelope is more likely to reflect discrete representation of transient information rather than oscillatory entrainment.SIGNIFICANCE STATEMENTThis study probes a highly debated topic in speech perception: the neural mechanisms underlying the cortical representation of the temporal envelope of speech. It is well established that the slow intensity profile of the speech signal, its envelope, elicits a robust brain response that “tracks” these envelope fluctuations. The oscillatory entrainment model posits that envelope tracking reflects phase alignment of endogenous neural oscillations. Here the authors provide evidence for a distinct mechanism. They show that neural speech envelope tracking arises from transient evoked neural responses to rapid increases in the speech envelope. Explicit computational modeling provides direct and compelling evidence that evoked responses are the primary mechanism underlying cortical speech envelope representations, with no evidence for oscillatory entrainment. |
| وصف الملف: | application/pdf |
| تدمد: | 1529-2401 0270-6474 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::7a641125ceb9148233980f5c12e15948 https://doi.org/10.1523/jneurosci.1663-22.2023 |
| حقوق: | OPEN |
| رقم الأكسشن: | edsair.doi.dedup.....7a641125ceb9148233980f5c12e15948 |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 15292401 02706474 |
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