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Visual Priming and Visual Hallucinations in Parkinson's Disease. Evidence for Normal Top-Down Processes

Lookup NU author(s): Sarah Straughan, Daniel Collerton


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Background: Visual hallucinations (VH) are common in Parkinson's disease (PD) and are associated with increased morbidity and mortality. Current explanations for VH in PD suggest combined impairments in top-down attentional and bottom-up perceptual processes, which allow the passive release of stored images. Alternative models in other disorders have suggested that top-down factors may actively encourage hallucinations. In order to explore the interaction between top-down and bottom-up visual processing in PDVH, we developed novel experimental priming tasks in which top-down verbal cues were used to prime the bottom-up recognition of partial or ambiguous pictures.Method: Two groups of PD participants with (PD + VH, n = 16), and without VH (PD - VH, n = 20) were compared to a group of healthy older adults (NC, n = 20) on 3 novel measures of visual priming.Results: All tasks showed significant priming effects. The PD + VH group was more impaired at accurately identifying silhouette and fragmented images compared to the PD - VH group. There were no differences in priming between the 2 PD groups.Conclusions: The study showed that VH in PD are not associated with relatively greater top-down activation, and that the interaction between top-down and bottom-up processes is intact.

Publication metadata

Author(s): Straughan S, Collerton D, Bruce V

Publication type: Article

Publication status: Published

Journal: Journal of Geriatric Psychiatry and Neurology

Year: 2016

Volume: 29

Issue: 1

Pages: 25-30

Print publication date: 01/01/2016

Online publication date: 30/05/2015

Acceptance date: 08/06/2015

ISSN (print): 0891-9887

ISSN (electronic): 1552-5708

Publisher: Sage Publications, Inc.


DOI: 10.1177/0891988715598237


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