TY  - JOUR
PY  - 2015//
TI  - Visual priming and visual hallucinations in Parkinson's disease. Evidence for normal top-down processes
JO  - Journal of geriatric psychiatry and neurology
A1  - Straughan, Sarah
A1  - Collerton, Daniel
A1  - Bruce, Vicki
SP  - 25
EP  - 30
VL  - 29
IS  - 1
N2  - 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. <br><br>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. <br><br>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. <br><br>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.<p />  <p>Language: en</p>
LA  - en
SN  - 0891-9887
UR  - http://dx.doi.org/10.1177/0891988715598237
ID  - ref1
ER  -