Oxyopia Abstract

October 18, 2002
Noon
489 Minor Hall

Jack Pettigrew FRS
Vision Touch and Hearing Research Center, School of Biomedical Sciences, University of Queensland, Brisbane, Australia
Host: Ralph Freeman

Title

"Perceptual rivalry: Ultradian clock or confused adolescent?"

Abstract

Perceptual rivalry is an oscillation of conscious experience that takes place despite unvarying, if ambiguous, sensory input. Much current interest is focused on the controversy over the neural site of binocular rivalry, for which different cortical regions have been implicated. Debate continues over the relative role of higher levels of processing compared with primary visual cortex and the suggestion that different forms of rivalry involve different cortical areas, while new evidence points to a role for subcortical sites (striatum) in the generation of the rivalry rhythm . The temporal pattern of disappearance and reappearance in motion-induced-blindness (MIB)(Bonneh, Cooperman, and Sagi, 2001) is highly correlated with the pattern of oscillation reported during binocular rivalry in the same individual. This correlation holds over a wide range of inter-individual variation. Temporal similarity in the two phenomena is also strikingly confirmed by the effects of the hallucinogens LSD and psilocybin, which produce the same, extraordinary, pattern of increased rhythmicity in both kinds of perceptual oscillation. Furthermore, MIB demonstrates two other properties previously considered characteristic of binocular rivalry (statistics of timing intervals and Levelt's second proposition). MIB therefore appears to be a form of perceptual rivalry. Taken together with similar information on other kinds of rivalry, it seems that a common brainstem oscillator may be responsible for timing aspects of all forms of perceptual rivalry. This shared, striatal oscillator thesis is highly relevant to the observation that rivalry rhythms are altered in the major psychoses.
www.uq.edu.au/nuq/jack/jack.html.

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