Neural oscillations: reconciling timing and meaning
Neural oscillations have been implicated in various cognitive functions, highlighting their logistical relevance in timing cognition. In humans, cortical oscillations may parse continuous speech signals into computational units (e.g. syllables or words) necessary for speech comprehension. Neural oscillations may serve as natural parsers for bottom-up acoustic parsing and may also be top-down modulated by available linguistic representations. Using magnetoencephalography, we contrasted acoustic and linguistic parsing using bistable speech sequences: while listening to speech sequences, participants were asked to maintain one of the two possible speech percepts through volitional control. The tracking of speech dynamics by neural oscillations was predict to not solely follow the acoustic properties but perhaps shift in time according to participant’s conscious speech percept. Our results showed two dissociable markers of neural-speech tracking under endogenous control: small modulations in low-frequency oscillations and variable latencies of high-frequency activity (sp. beta and gamma bands). While changes in low-frequency neural oscillations are compatible with the encoding of pre-lexical segmentation cues, high-frequency activity informed on an individual’s conscious speech percept. These and other results will help feed a discussion on the functional role of neural oscillations in representing meaning and/or time.