High-frequency neural activity predicts word parsing in ambiguous speech streams.
During speech listening, the brain parses a continuous acoustic stream of information into computational units (e.g., syllables or words) necessary for speech comprehension. Recent neuroscientific hypotheses have proposed that neural oscillations contribute to speech parsing, but whether they do so on the basis of acoustic cues (bottom-up acoustic parsing) or as a function of available linguistic representations (top-down linguistic parsing) is unknown. In this magnetoencephalography study, we contrasted acoustic and linguistic parsing using bistable speech sequences. While listening to the speech sequences, participants were asked to maintain one of the two possible speech percepts through volitional control. We predicted that the tracking of speech dynamics by neural oscillations would not only follow the acoustic properties but also shift in time according to the participant's conscious speech percept. Our results show that the latency of high-frequency activity (specifically, beta and gamma bands) varied as a function of the perceptual report. In contrast, the phase of low-frequency oscillations was not strongly affected by top-down control. Whereas changes in low-frequency neural oscillations were compatible with the encoding of prelexical segmentation cues, high-frequency activity specifically informed on an individual's conscious speech percept.
Cognitive Neuroimaging Unit, CEA DRF/I2BM, Institut National de la Santé et de la Recherche Médicale, Université Paris-Sud, Université Paris-Saclay, Gif/Yvette, France; a.kosem@donders.ru.nl.|Radboud University, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands.|Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands; and.
Anne
A
Kösem
Cognitive Neuroimaging Unit, CEA DRF/I2BM, Institut National de la Santé et de la Recherche Médicale, Université Paris-Sud, Université Paris-Saclay, Gif/Yvette, France.|SCALab, Centre National de la Recherche Scientifique UMR 9193, Université Lille, Lille, France.
Anahita
A
Basirat
Cognitive Neuroimaging Unit, CEA DRF/I2BM, Institut National de la Santé et de la Recherche Médicale, Université Paris-Sud, Université Paris-Saclay, Gif/Yvette, France.
Leila
L
Azizi
Cognitive Neuroimaging Unit, CEA DRF/I2BM, Institut National de la Santé et de la Recherche Médicale, Université Paris-Sud, Université Paris-Saclay, Gif/Yvette, France.
Virginie
V
van Wassenhove
D000161:Acoustic Stimulation; D000704:Analysis of Variance; D001931:Brain Mapping; D058256:Brain Waves / Q000502:physiology*; D032882:Comprehension / Q000502:physiology*; D005260:Female; D006801:Humans; D008037:Linguistics; D015225:Magnetoencephalography; D008297:Male; D011930:Reaction Time / Q000502:physiology; D013057:Spectrum Analysis; D013060:Speech / Q000502:physiology*; D013067:Speech Perception / Q000502:physiology*; D014825:Vocabulary; D055815:Young Adult
MEG; bistability; neural entrainment; phase; speech segmentation