Ambiguous figures and binding: EEG frequency modulations during multistable perception.
Ambiguous figures induce sudden transitions between rivaling percepts. We investigated electroencephalogram frequency modulations of accompanying change-related de- and rebinding processes. Presenting the stimuli discontinously, we synchronized perceptual reversals with stimulus onset, which served as a time reference for averaging. The resultant gain in temporal resolution revealed a sequence of time-frequency correlates of the reversal process. Most conspicuous was a transient right-hemispheric gamma modulation preceding endogenous reversals by at least 200 ms. No such modulation occurred with exogenously induced reversals of unambiguous stimulus variants. Post-onset components were delayed for ambiguous compared to unambiguous stimuli. The time course of oscillatory activity differed in several respects from predictions based on binding-related hypotheses. The gamma modulation preceding endogenous reversals may indicate an unstable brain state, ready to switch.
Ehm
Werner
W
Institute for Frontier Areas of Psychology and Mental Health, Freiburg, Germany Universitäts-Augenklinik, Freiburg, Germany.
Bach
Michael
M
Kornmeier
Jürgen
J
D000328:Adult; D003627:Data Interpretation, Statistical; D004569:Electroencephalography; D005074:Evoked Potentials, Visual; D005260:Female; D005583:Fourier Analysis; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D015348:Vision, Binocular / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult