Theta-gamma phase-amplitude coupling in auditory cortex is modulated by language proficiency
Date
2023Author
Lizarazu, Mikel
Carreiras, Manuel
Molinaro, Nicola
Metadata
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Lizarazu, M., Carreiras, M., & Molinaro, N. (2023). Theta-gamma phase-amplitude coupling in auditory cortex is modulated by language proficiency. Human Brain Mapping, 44( 7), 2862– 2872. https://doi.org/10.1002/hbm.26250
Human Brain Mapping
Human Brain Mapping
Abstract
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.