title: Gamma oscillations as a neural signature of shifting times in narrative language.
abstract: Verbs and other temporal expressions allow speakers to specify the location of events in time, as well as to move back and forth in time, shifting in a narrative between past, present and future. The referential flexibility of temporal expressions is well understood in linguistics but its neurocognitive bases remain unknown. We aimed at obtaining a neural signature of shifting times in narrative language. We recorded and analyzed event-related brain potentials (ERPs) and oscillatory responses to the adverb 'now' and to the second main verb in Punctual ('An hour ago the boy stole a candy and now he peeled the fruit') and Iterative ('The entire afternoon the boy stole candy and now he peeled the fruit') contexts. 'An hour ago' introduces a time frame that lies entirely in the past, 'now' shifts the narrative to the present, and 'peeled' shifts it back to the past. These two referential shifts in Punctual contexts are expected to leave very similar traces on neural responses. In contrast, 'The entire afternoon' specifies a time frame that may encompass past, present and future, such that both 'now' and 'peeled' are consistent with it. Here, no time shift is required. We found no difference in ERPs between Punctual and Iterative contexts either at 'now' or at the second verb. However, reference shifts modulated oscillatory signals. 'Now' and the second verb in Punctual contexts resulted in similar responses: an increase in gamma power with a left-anterior distribution. Gamma bursts were absent in Iterative contexts. We propose that gamma oscillations here reflect the binding of temporal variables to the values allowed by constraints introduced by temporal expressions in discourse.
authors: Center for Language and Cognition, University of Groningen, Groningen, Netherlands; NeuroImaging Center, University Medical Center Groningen, Groningen, Netherlands.
authors: Sanne Gøren
authors: SG
authors: Brederoo
authors: Center for Language and Cognition, University of Groningen, Groningen, Netherlands; NeuroImaging Center, University Medical Center Groningen, Groningen, Netherlands.
authors: Laura Simone
authors: LS
authors: Bos
authors: Center for Language and Cognition, University of Groningen, Groningen, Netherlands; National Research University Higher School of Economics, Moscow, Russia.
authors: Olga
authors: O
authors: Dragoy
authors: Center for Language and Cognition, University of Groningen, Groningen, Netherlands.
authors: Roelien
authors: R
authors: Bastiaanse
authors: Brain and Language Lab, International School for Advanced Studies, Trieste, Italy; Language Acquisition and Language Processing Lab, Department of Language and Literature, Norwegian University of Science and Technology, Trondheim, Norway.
authors: Giosuè
authors: G
authors: Baggio
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D007802:Language; D008037:Linguistics / Q000379:methods; D008297:Male; D013995:Time; D055815:Young Adult