Phase−amplitude coupling between theta and gamma oscillations adapts to speech rate
Fecha
2019Autor
Lizarazu, Mikel
Lallier, Marie
Molinaro, Nicola
Metadatos
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Lizarazu, M. , Lallier, M. and Molinaro, N. (2019), Phase−amplitude coupling between theta and gamma oscillations adapts to speech rate. Ann. N.Y. Acad. Sci., 1453: 140-152. doi:10.1111/nyas.14099
Resumen
Low- and high-frequency cortical oscillations play an important role in speech processing. Low-frequency neural oscillations in the delta (<4Hz) 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 (28−40Hz), 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.