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Visual search deficits in Parkinson's disease are attenuated by bottom-up target salience and top-down information.

Abstract：

:Patients with Parkinson's disease (PD), a degenerative disorder primarily affecting the nigrostriatal dopamine system, exhibit deficits in selecting task-relevant stimuli in the presence of irrelevant stimuli, such as in visual search tasks. However, results from previous studies suggest that these deficits may vary as a function of whether selection must rely primarily on the "bottom-up" salience of the target relative to background stimuli, or whether "top-down" information about the identity of the target is available to bias selection. In the present study, moderate-to-severe medicated PD patients and age-matched controls were tested on six visual search tasks that systematically varied the relationship between bottom-up target salience (feature search, noisy feature search, conjunction search) and top-down target knowledge (Target Known versus Target Unknown). Comparison of slope and intercepts of the RT x set size function provided information about the efficiency of search and non-search (e.g., decision, response) components, respectively. Patients exhibited higher intercepts than controls as bottom-up target salience decreased, however these deficits were disproportionately larger under Target Unknown compared to Target Known conditions. Slope differences between PD and controls were limited to the Target Unknown Conjunction condition, where patients exhibited a shallower slope in the target absent condition, indicating that they terminated search earlier. These results suggest that under conditions of high background noise, medicated PD patients were primarily impaired in decision and/or response processes downstream from the target search itself, and that the deficit was attenuated when top-down information was available to guide selection of the target signal.

journal_name

Neuropsychologia

journal_title

Neuropsychologia

authors

Horowitz TS,Choi WY,Horvitz JC,Côté LJ,Mangels JA

doi

10.1016/j.neuropsychologia.2006.01.037

subject

Has Abstract

pub_date

2006-01-01 00:00:00

pages

1962-77

issue

eissn

0028-3932

issn

1873-3514

pii

S0028-3932(06)00044-3

journal_volume

pub_type

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Visual search deficits in Parkinson's disease are attenuated by bottom-up target salience and top-down information.