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Visual aftereffects in schizophrenia
Psychosis—a cardinal symptom of schizophrenia—has been associated with a failure to appropriately create or use stored regularities to guide the interpretation of incoming information, leading to abnormal perceptions and beliefs. The visual system provides a test bed for investigating the role of prior experience and prediction as accumulated knowledge of the world informs our current perception. Visual aftereffects, illusory percepts that arise after prolonged viewing of a visual stimulus, serve as a valuable measure of the influence of prior experience on current visual processing. These aftereffects arise via neural adaptation: a reduction in neural firing with prolonged viewing of a particular stimulus. In the current study, we measured two types of visual aftereffects which reflect neural adaptation to luminance (negative afterimages) and orientation (tilt aftereffect) in persons with schizophrenia (PSZ) and demographically-matched controls (HC). PSZ show stronger tilt aftereffects, but not negative afterimages. Specific neuronal populations adapt for various types of aftereffects to occur, and these findings suggest that altered neural adaptation is evident in cortical, but not retinal or subcortical, stages of a visual processing hierarchy in schizophrenia. Thus, these findings may help reveal at what level of a sensory hierarchy altered predictive processing in psychosis emerges.