TY - JOUR T1 - Acoustically driven cortical delta oscillations underpin prosodic chunking JF - eneuro JO - eNeuro DO - 10.1523/ENEURO.0562-20.2021 SP - ENEURO.0562-20.2021 AU - JM Rimmele AU - D Poeppel AU - O Ghitza Y1 - 2021/06/01 UR - http://www.eneuro.org/content/early/2021/06/02/ENEURO.0562-20.2021.abstract N2 - Oscillation-based models of speech perception postulate a cortical computational principle by which decoding is performed within a window structure derived by a segmentation process. Segmentation of syllable-size chunks is realized by a theta oscillator. We provide evidence for an analogous role of a delta oscillator in the segmentation of phrase-sized chunks. We recorded Magnetoencephalography (MEG) in humans, while participants performed a target identification task. Random-digit strings, with phrase-long chunks of two digits, were presented at chunk rates of 1.8 Hz or 2.6 Hz, inside or outside the delta frequency band (defined here to be 0.5 - 2 Hz). Strong periodicities were elicited by chunk rates inside of delta in superior, middle temporal areas and speech-motor integration areas. Periodicities were diminished or absent for chunk rates outside delta, in line with behavioral performance. Our findings show that prosodic chunking of phrase-sized acoustic segments is correlated with acoustic-driven delta oscillations, expressing anatomically specific patterns of neuronal periodicities.Significance StatementOscillation-based models of speech perception postulate a cortical computational principle by which decoding is performed within a time-varying window structure, synchronized with the input on multiple time scales. At pre-lexical level, cycles of a flexible theta oscillator – locked to the input syllabic rhythm – constitute the syllabic windows. We find that the presence of cortical delta oscillations correlates with whether or not an input phrase-sized chunk rate is inside the delta range. This suggests that at the phrase time scale, a delta oscillator could play a role analogous to that of the theta oscillator at the syllable level. The segmentation process is realized by a flexible delta oscillator locked to the input rhythm, with delta cycles constituting phrase-sized windows. ER -