title: Disrupting morphosyntactic and lexical semantic processing has opposite effects on the sample entropy of neural signals.
abstract: Converging evidence in neuroscience suggests that syntax and semantics are dissociable in brain space and time. However, it is possible that partly disjoint cortical networks, operating in successive time frames, still perform similar types of neural computations. To test the alternative hypothesis, we collected EEG data while participants read sentences containing lexical semantic or morphosyntactic anomalies, resulting in N400 and P600 effects, respectively. Next, we reconstructed phase space trajectories from EEG time series, and we measured the complexity of the resulting dynamical orbits using sample entropy - an index of the rate at which the system generates or loses information over time. Disrupting morphosyntactic or lexical semantic processing had opposite effects on sample entropy: it increased in the N400 window for semantic anomalies, and it decreased in the P600 window for morphosyntactic anomalies. These findings point to a fundamental divergence in the neural computations supporting meaning and grammar in language.
authors: Center of Mathematics, Computation and Cognition, ABC Federal University, Rua Santa Adélia 166, 09210-170 Santo André, Brazil.
authors: André
authors: A
authors: Fonseca
authors: SISSA International School for Advanced Studies, via Bonomea 265, 34136 Trieste, Italy.
authors: Vezha
authors: V
authors: Boboeva
authors: Center for Language and Cognition and NeuroImaging Center, University of Groningen, Postbus 716, 9700 AS Groningen, Netherlands.
authors: Sanne
authors: S
authors: Brederoo
authors: Language Acquisition and Language Processing Lab, Norwegian University of Science and Technology, 7491 Trondheim, Norway. Electronic address: giosue.baggio@ntnu.no.
authors: Giosuè
authors: G
authors: Baggio
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D008297:Male; D008606:Mental Processes; D009474:Neurons / Q000502:physiology*; D011932:Reading; D012660:Semantics; D055815:Young Adult