title: Boosting up gamma-band oscillations leaves target-stimulus in masking out of awareness: Explaining an apparent paradox.
abstract: Boost up gamma-band neuronal oscillations have been interpreted as a correlate of pertinent stimulus awareness. The validity of this observation-based conclusion can be rigorously tested if the basic methodological rule of investigating neural correlates of consciousness (NCC) is followed: the varying contents of consciousness should be contrasted with invariant stimulation. We asked whether reliable gamma-band oscillations recorded from primary visual cortex appear as signatures of target awareness in metacontrast masking with invariant stimulation parameters. Surprisingly, clear target-stimuli awareness was associated with less expressed gamma power. However, because when target awareness was effectively masked more gamma power of the EEG response was found, and because this gamma-boost emerged at the post-target time when mask information was presented, we were able to explain our results as target substitution in consciousness by mask representation due to enhanced mask processing.
authors.affiliation: Institute of Psychology, Humboldt University of Berlin, Germany.
authors.forename: Jaan
authors.initials: J
authors.lastname: Aru
authors.forename: Talis
authors.initials: T
authors.lastname: Bachmann
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D001364:Awareness / Q000502:physiology*; D001683:Biological Clocks / Q000502:physiology*; D003243:Consciousness / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D006801:Humans; D008297:Male; D009415:Nerve Net / Q000502:physiology; D009474:Neurons / Q000502:physiology; D009483:Neuropsychological Tests; D010470:Perceptual Masking / Q000502:physiology; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology; D013997:Time Factors; D014793:Visual Cortex / Q000502:physiology*; D055815:Young Adult