Delta(but not theta)‐band cortical entrainment involves speech‐specific processing

Molinaro, Nicola; Lizarazu, Mikel

doi:10.1111/ejn.13811

Cited by 113 publications

(142 citation statements)

References 30 publications

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“…More important for our claims, we did not find clear evidence of PAC involving the delta band. This could indicate that the delta band speech tracking component is not as sensitive to the acoustic properties of speech as other frequency bands (theta and gamma), and possibly suggest it is more related to endogenous language−related processes …”

Section: Discussionmentioning

confidence: 99%

“…This could indicate that the delta band speech tracking component is not as sensitive to the acoustic properties of speech as other frequency bands (theta and gamma), and possibly suggest it is more related to endogenous language−related processes. 9 The frequency-adaptive nested gamma response to the fine-grain structure of the auditory signal could explain experimental evidence suggesting that auditory cortical entrainment influences word recognition. 26,28 If the nested high-frequency gamma response adapts to the fine-grain structure of the speech signal, it is possible that ongoing faster (or slower) low-frequency entrainment to faster (or slower) speech input directly affects the perception of words that have ambiguous meanings due to the intermediate duration of a key phoneme.…”

Section: Discussionmentioning

confidence: 99%

“…The envelope of the audio signals was estimated by using a filter bank that models the passage of the signal through the cochlea . − Coherence between the speech envelope and neural activity in each voxel of both ROIs was obtained in the 0.5−10 Hz frequency band with 0.5 Hz frequency resolution . The average coherence value of all voxels in LAC and RAC was calculated for each participant, condition, and frequency bin.…”

Section: Methodsmentioning

confidence: 99%

“…Temporal sampling is achieved in part via the entrainment of low‐frequency neural oscillations (<10 Hz) to the slow temporal modulations of speech . More specifically, the phase of delta (<4 Hz) and theta (4−8 Hz) oscillations in auditory regions, respectively, tracks prosodic and syllabic rhythms during speech processing . Interestingly, while the theta band component reflects acoustic tracking of the speech input, the delta band appears to be sensitive to language‐related processes related to syntactic properties of the speech input .…”

Section: Introductionmentioning

confidence: 99%

“…[4][5][6] More specifically, the phase of delta (<4 Hz) and theta (4−8 Hz) oscillations in auditory regions, respectively, tracks prosodic and syllabic rhythms during speech processing. [7][8][9] Interestingly, while the theta band component reflects acoustic tracking of the speech input, the delta band appears to be sensitive to language-related processes related to syntactic properties of the speech input. 10 Furthermore, theta band oscillations impose periods of excitation and inhibition on high-frequency oscillations (gamma band: 25−40 Hz), a mechanism proposed to contribute to rapid decoding of high-frequency information needed to process phonemes in the speech signal.…”

Section: Introductionmentioning

confidence: 99%

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Phase−amplitude coupling between theta and gamma oscillations adapts to speech rate

Lizarazu

Lallier

Molinaro

2019

Annals of the New York Academy of Sciences

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Low‐ and high‐frequency cortical oscillations play an important role in speech processing. Low‐frequency neural oscillations in the delta (<4 Hz) and theta (4–8 Hz) bands entrain to the prosodic and syllabic rates of speech, respectively. Theta band neural oscillations modulate high‐frequency neural oscillations in the gamma band (28−40 Hz), which have been hypothesized to be crucial for processing phonemes in natural speech. Since speech rate is known to vary considerably, both between and within talkers, it has yet to be determined whether this nested gamma response reflects an externally induced rhythm sensitive to the rate of the fine‐grained structure of the input or a speech rate−independent endogenous response. Here, we recorded magnetoencephalography responses from participants listening to a speech delivered at different rates: decelerated, normal, and accelerated. We found that the phase of theta band oscillations in left and right auditory regions adjusts to speech rate variations. Importantly, we showed that the peak of the gamma response—coupled to the phase of theta—follows the speech rate. This indicates that gamma activity in auditory regions synchronizes with the fine‐grain properties of speech, possibly reflecting detailed acoustic analysis of the input.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Phase−amplitude coupling between theta and gamma oscillations adapts to speech rate

Lizarazu

Lallier

Molinaro

2019

Annals of the New York Academy of Sciences

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Theta‐gamma phase‐amplitude coupling in auditory cortex is modulated by language proficiency

Lizarazu

Carreiras

Molinaro

2023

Human Brain Mapping

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The coordination between the theta phase (3–7 Hz) and gamma power (25–35 Hz) oscillations (namely theta‐gamma phase‐amplitude coupling, PAC) in the auditory cortex has been proposed as an essential neural mechanism involved in speech processing. However, it has not been established how this mechanism is related to the efficiency with which a listener processes speech. Speech processing in a non‐native language offers a useful opportunity to evaluate if theta‐gamma PAC is modulated by the challenges imposed by the reception of speech input in a non‐native language. The present study investigates how auditory theta‐gamma PAC (recorded with magnetoencephalography) is modulated in both native and non‐native speech reception. Participants were Spanish native (L1) speakers studying Basque (L2) at three different levels: beginner (Grade 1), intermediate (Grade 2), and advanced (Grade 3). We found that during L2 speech processing (i) theta‐gamma PAC was more highly coordinated for intelligible compared to unintelligible speech; (ii) this coupling was modulated by proficiency in Basque being lower for beginners, higher for intermediate, and highest for advanced speakers (no difference observed in Spanish); (iii) gamma power did not differ between languages and groups. These findings highlight how the coordinated theta‐gamma oscillatory activity is tightly related to speech comprehension: the stronger this coordination is, the more the comprehension system will proficiently parse the incoming speech input.

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Distinct roles of delta‐ and theta‐band neural tracking for sharpening and predictive coding of multi‐level speech features during spoken language processing

Mai,

Wang

2023

Human Brain Mapping

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The brain tracks and encodes multi‐level speech features during spoken language processing. It is evident that this speech tracking is dominant at low frequencies (<8 Hz) including delta and theta bands. Recent research has demonstrated distinctions between delta‐ and theta‐band tracking but has not elucidated how they differentially encode speech across linguistic levels. Here, we hypothesised that delta‐band tracking encodes prediction errors (enhanced processing of unexpected features) while theta‐band tracking encodes neural sharpening (enhanced processing of expected features) when people perceive speech with different linguistic contents. EEG responses were recorded when normal‐hearing participants attended to continuous auditory stimuli that contained different phonological/morphological and semantic contents: (1) real‐words, (2) pseudo‐words and (3) time‐reversed speech. We employed multivariate temporal response functions to measure EEG reconstruction accuracies in response to acoustic (spectrogram), phonetic and phonemic features with the partialling procedure that singles out unique contributions of individual features. We found higher delta‐band accuracies for pseudo‐words than real‐words and time‐reversed speech, especially during encoding of phonetic features. Notably, individual time‐lag analyses showed that significantly higher accuracies for pseudo‐words than real‐words started at early processing stages for phonetic encoding (<100 ms post‐feature) and later stages for acoustic and phonemic encoding (>200 and 400 ms post‐feature, respectively). Theta‐band accuracies, on the other hand, were higher when stimuli had richer linguistic content (real‐words > pseudo‐words > time‐reversed speech). Such effects also started at early stages (<100 ms post‐feature) during encoding of all individual features or when all features were combined. We argue these results indicate that delta‐band tracking may play a role in predictive coding leading to greater tracking of pseudo‐words due to the presence of unexpected/unpredicted semantic information, while theta‐band tracking encodes sharpened signals caused by more expected phonological/morphological and semantic contents. Early presence of these effects reflects rapid computations of sharpening and prediction errors. Moreover, by measuring changes in EEG alpha power, we did not find evidence that the observed effects can be solitarily explained by attentional demands or listening efforts. Finally, we used directed information analyses to illustrate feedforward and feedback information transfers between prediction errors and sharpening across linguistic levels, showcasing how our results fit with the hierarchical Predictive Coding framework. Together, we suggest the distinct roles of delta and theta neural tracking for sharpening and predictive coding of multi‐level speech features during spoken language processing.

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Delta(but not theta)‐band cortical entrainment involves speech‐specific processing

Cited by 113 publications

References 30 publications

Phase−amplitude coupling between theta and gamma oscillations adapts to speech rate

Phase−amplitude coupling between theta and gamma oscillations adapts to speech rate

Theta‐gamma phase‐amplitude coupling in auditory cortex is modulated by language proficiency

Distinct roles of delta‐ and theta‐band neural tracking for sharpening and predictive coding of multi‐level speech features during spoken language processing

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