title: Successful memory encoding is associated with increased cross-frequency coupling between frontal theta and posterior gamma oscillations in human scalp-recorded EEG.
abstract: Although previous studies have established that successful memory encoding is associated with increased synchronization of theta-band and gamma-band oscillations, it is unclear if there is a functional relationship between oscillations in these frequency bands. Using scalp-recorded EEG in healthy human participants, we demonstrate that cross-frequency coupling between frontal theta phase and posterior gamma power is enhanced during the encoding of visual stimuli which participants later on remember versus items which participants subsequently forget ("subsequent memory effect," SME). Conventional wavelet analyses and source localizations revealed SMEs in spectral power of theta-, alpha-, and gamma-band. Successful compared to unsuccessful encoding was reflected in increased theta-band activity in right frontal cortex as well as increased gamma-band activity in parietal-occipital regions. Moreover, decreased alpha-band activity in prefrontal and occipital cortex was also related to successful encoding. Overall, these findings support the idea that during the formation of new memories frontal cortex regions interact with cortical representations in posterior areas.
authors.affiliation: University Medical Center Hamburg-Eppendorf, Department of Neurophysiology and Pathophysiology, Hamburg, Germany; Institute of Psychology, University of Osnabrueck, Germany. Electronic address: u.friese@uke.de.
authors.forename: Uwe
authors.initials: U
authors.lastname: Friese
authors.affiliation: Institute of Psychology, University of Osnabrueck, Germany; Institute of Cognitive Science, University of Osnabrueck, Germany.
authors.forename: Moritz
authors.initials: M
authors.lastname: Köster
authors.affiliation: Institute of Psychology, University of Osnabrueck, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Hassler
authors.affiliation: Institute of Psychology, University of Osnabrueck, Germany.
authors.forename: Ulla
authors.initials: U
authors.lastname: Martens
authors.affiliation: Cuban Neuroscience Center, Havana, Cuba.
authors.forename: Nelson
authors.initials: N
authors.lastname: Trujillo-Barreto
authors.affiliation: Institute of Psychology, University of Osnabrueck, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Gruber
mesh_terms: D001921:Brain / Q000502:physiology*; D003344:Cortical Synchronization / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D012535:Scalp; D055815:Young Adult
keywords: Cross-frequency-coupling; EEG; Gamma-band; Memory encoding; Oscillations; Theta-band