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Tori Espensen-Sturges, Philip Burton, Scott Sponheim, Cheryl Olman; Relationship Between Iterative Visual Processing Deficits and Psychotic Symptoms. Journal of Vision 2018;18(10):33. doi: https://doi.org/10.1167/18.10.33.
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Feedforward and feedback signals between specialized visual areas create iterative processing loops that combine information across receptive fields and increase processing efficiency. A variety of visual processing deficits have been observed in psychosis that seem to exist separately from generalized deficits and may be explained by abnormal iterative processing. In an effort to isolate and better understand the components of these loops in visual deficits in psychosis, we presented schizophrenia patients, bipolar patients, and controls with arrays of short line segments describing an object set on a background of parallel line segments as part of an MRI experiment. Stimuli were defined as being either meaningful objects or meaningless clusters of line segments based on a separate categorization experiment. BOLD responses in primary visual cortex (V1) and lateral occipital complex (LOC) were estimated using a general linear model, and connectivity measures were determined using a generalized psychophysiological interaction analysis. There were no group differences in any visual ROI; however, there were negative correlations between LOC activation and self-reported difficulty modulating stimulus intensity, as well as absorption, a personality trait associated with psychosis. A generalized PPI analysis using V1 as a seed region revealed differential relationships with the right LOC and a medial frontal cluster (BA 9) depending on stimulus condition. The relationship between V1 and rLOC was positive for meaningless stimuli and negative for meaningful stimuli; this pattern was reversed for the relationship between V1 and BA9. The magnitude of the difference in correlation strength between meaningful and meaningless objects was associated with more severe negative psychotic symptoms, strengthening the suggestion that processing in psychosis may be better understood in terms of psychotic symptomatology than diagnosis. In addition, relationships involving multiple stages in the visual processing stream with symptomatology highlight the importance of deficits in iterative processing in psychotic disorders.
Meeting abstract presented at VSS 2018
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