Asymmetries in the covert orienting of visual spatial attention to spatial and non-spatial cues in Alzheimer's disease

Brain : a Journal of Neurology
P MaruffJ N Currie

Abstract

The ability to direct covert visual spatial attention to the left (LVF) and right visual field (RVF) was examined in 15 patients with mild to moderate Alzheimer's disease and 15 age- and education-matched controls using the covert orienting of visual spatial attention task (COVAT) modified to include both spatial and non-spatial cues. Subjects responded with a button press when they detected a target at a location 8 degrees to either the left or right of fixation. On 70% of trials a spatial cue was flashed at the target location before the target appeared. On 15% of trials the spatial cue was flashed at the location contralateral to where it would appear and on the remaining 15% of trials non-spatial diffuse cue preceded targets. The cue to target interval (CTI) varied between 150 and 550 ms. Mean reaction times for each cuetype in the RVF and LVF were calculated. Compared with controls, the percentage of trials excluded because of very slow reaction times was significantly greater in the Alzheimer's disease group for the 550 ms CTI. Analysis of the symmetry of reaction times to LVF and RVF targets for the 150 ms CTI enabled us to classify Alzheimer's disease subjects into three subgroups based on the hemifield of abnormally sl...Continue Reading

Citations

Jun 6, 2000·Neuropsychologia·R ParasuramanG E Alexander
Apr 13, 2002·Neuropsychology·Raja ParasuramanTrey Sunderland
Oct 27, 2007·Brain and Cognition·B A Castro-BarrosL E Ribeiro-do-Valle
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Nov 16, 2021·Seminars in Ophthalmology·Gemma Almario, David P Piñero

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