Understanding the mechanisms that control the dynamics of perceptual switches

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DESCRIPTION (provided by applicant): When a static visual scene is viewed, different objects and organizations can spontaneously come to dominate visual awareness. These "perceptual switches" that activate alternative scene interpretations are important because they allow detection of behaviorally significant information that may not be predictable or initially salient and that may exist at any level of organization. The literature on binocular rivalry (a paradigm commonly used to study perceptual switches) suggests that perceptual switches are mediated by collective action of multi-stage neural competition involving component processes such as signal transduction, adaptation, inhibitory interactions, stochastic noise, non-linearity (e.g., a threshold), and response synchronization. Contemporary dynamic models provide a plausible computational framework for integrating these component processes. However, research to date has overlooked some key aspects of perceptual switches. Prominently, no attempts have been made to measure the component processes to determine how their actual (as opposed to hypothesized) properties predict the dynamics of perceptual switches. Without this knowledge, it is impossible to specify the sources of the substantial individual differences and plasticity observed in the dynamics of perceptual switches. Further, in spite of growing evidence that multi-level processes are involved, little data exist regarding how neural competition at multiple processing stages interactively controls perceptual switches. Our basic strategy will be to psychophysically and electrophysiologically measure the component processes operating at different processing stages, determine how each component process contributes to perceptual switches, and use this information to revise the current models. The advanced model will predict the dynamics of perceptual switches for each individual on the basis of his or her measured component processes. In this way, we will determine the unexplained sources of substantial variability in perceptual switches due to individual differences, plasticity, percept-to-percept variability, and intentional control. Finally, to begin to translate the basic research on perceptual switching to a broader understanding of mental health and visual attention, we will (1) use the model to trace the sources of unusual perceptual dynamics associated with some psychiatric disorders to specific component processes, and (2) determine how the component processes underlying perceptual switches and their intentional modulations are associated with voluntary attention abilities. PUBLIC HEALTH RELEVANCE: Visual scenes often give rise to multiple interpretations; people function most effectively when they achieve a balance between the stability of a single interpretation and the flexibility to see alternative interpretations. Perceptual interpretations can be excessively unstable or excessively inflexible in a number of neurological and psychiatric disorders, including attention deficit disorder and bipolar disorder. The dynamics of these perceptual alternations will be rigorously examined using a binocular-rivalry paradigm together with psychophysical, computational modeling, and electrophysiological techniques to reveal the underlying neural mechanisms and how they differ as a function of the health status of the individual.