Binocular rivalry reveals a dissociation between the subjective experience and induced gamma oscillations

Binocular rivalry occurs when separate incompatible images are presented, one to each eye. The subjective experience of viewing these stimuli is not of a fused image, rather the perceiver experiences either one or the other percept alternating across time. Manipulation of rivalry transfer, through an abrupt focal contrast change, causes the emerging percept to radiate across the declining image. This spreading percept transition has been likened to a wave of neural excitation propagating across the excitable medium of the visual cortex [H.R. Wilson et al. (2001) Nature, 412, 907-910; S.H. Lee et al. (2005) Nat. Neurosci., 8, 22-23]. Electrophysiologically, scalp-recorded gamma oscillations (30-70 Hz) have been reported to persist for several hundred milliseconds in response to changes in the subjective experience induced by alterations in incoming sensory information (moving-bar stimuli). Here, we used electroencephalographic recordings in the human and binocular rivalry transition to assess the role of scalp-recorded gamma in purely subjective changes in the visual experience. Despite the protraction of perceptual binding over a 900 ms period, no deviation in the pattern of induced gamma was observed from that reported during the perceptual closure of static images. These results suggest that localized scalp-recorded gamma oscillations are dissociable from the subjective visual experience.