Poster C22, Wednesday, August 21, 2019, 10:45 am – 12:30 pm, Restaurant Hall
Alpha Oscillations mark the Interaction between Language Processing and Cognitive Control Operations during Sentence Reading
René Terporten1, Anne Kösem3, Jan-Mathijs Schoffelen2, Eleanor Callaghan1, Karin Heidlmayr1, Bohan Dai2, Peter Hagoort1,2;1Max Planck Institute for Psycholinguistics, 2Donders Centre for Cognitive Neuroimaging, 3Lyon Neuroscience Research Center
A sentence’s context dynamically and flexibly constraints the way in which semantics are processed by the reader. It is suggested that this process engages an interaction between brain mechanisms that predict upcoming linguistic input and mechanisms that control information flow based on the amount of information provided by past sentential context. In a series of experiments, we put this to the test by focusing on the functional role of alpha oscillations as a marker for the effects of sentence context constraints onto brain dynamics. In a magnetoencephalography study, participants read a word-by-word presentation of sentences. These sentences belonged to linguistically matched lists of three levels of context constraints (high, medium and low constraints), defined by the sentences’ cloze probability. Prior to a sentence’s congruent target word, alpha oscillatory dynamics were investigated. The results indicated that alpha power was non-monotonically related to the degree of context constraint. Source reconstruction localized this effect to parietal areas, which connected to left and right frontal and left temporal areas differently, depending on the degree of constraint. Because of the non-monotonic alpha power modulation and its connectivity profile, these results were interpreted in light of cognitive control operations during language processing. To further investigate this interpretation, a subsequent electroencephalography experiment made use of the same paradigm, but introduced the probability of target word congruency as an additional factor. Groups of participants were compared that read either blocks of sentences with mainly (80%) congruent or (80%) incongruent sentence endings. We predicted that the congruency probabilities have an effect on alpha band dynamics during sentence processing. Specifically, we expected that cognitive control operations (involved in target word prediction) will suppress linguistic predictions more strongly in the 80% incongruent sentence ending condition, because the predictions that result from past sentential context are made mostly irrelevant in this task setting. This should be reflected by an effect on alpha power, as we hypothesized that alpha oscillations reflect cognitive control operations within this task setting. In sum, this line of research highlights the role of alpha oscillations and its role as a functional marker of context constraints during language processing. In addition, it emphasizes the dynamic interaction of what is commonly defined as a core language network and networks that support cognitive control operations.
Themes: Meaning: Combinatorial Semantics, Control, Selection, and Executive Processes
Method: Electrophysiology (MEG/EEG/ECOG)