Naturalistic Spoken Language Comprehension Is Supported by Alpha and Beta Oscillations

Brain oscillations are prevalent in all species and are involved in numerous perceptual operations. a oscillations are thought to facilitate processing through the inhibition of task-irrelevant networks, while # oscillations are linked to the putative reac-tivation of content representations. Can the proposed functional role of a and # oscillations be generalized from low-level operations to higher-level cognitive processes? Here we address this question focusing on naturalistic spoken language com-prehension. Twenty-two (18 female) Dutch native speakers listened to stories in Dutch and French while MEG was recorded. We used dependency parsing to identify three dependency states at each word: the number of (1) newly opened dependen-cies, (2) dependencies that remained open, and (3) resolved dependencies. We then constructed forward models to predict a and # power from the dependency features. Results showed that dependency features predict a and # power in language -related regions beyond low-level linguistic features. Left temporal, fundamental language regions are involved in language comprehension in a, while frontal and parietal, higher-order language regions, and motor regions are involved in #. Critically, a- and #-band dynamics seem to subserve language comprehension tapping into syntactic structure building and semantic composition by providing low-level mechanistic operations for inhibition and reactivation processes. Because of the temporal similarity of the a-# responses, their potential functional dissociation remains to be elucidated. Overall, this study sheds light on the role of a and # oscillations during naturalistic spoken language comprehension, providing evidence for the generalizability of these dynamics from perceptual to complex linguistic processes.