The Number of Attentional Foci and Their Precision Are Dissociated in the Posterior Parietal Cortex

Many everyday tasks require us to track moving objects with attention. The demand for attention increases both when more targets are tracked and when the targets move faster. These 2 aspects of attention—assigning multiple attentional foci (or indices) to targets and monitoring each focus with preci...

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Bibliographic Details
Published in:Cerebral cortex (New York, N.Y. 1991) N.Y. 1991), 2010-06, Vol.20 (6), p.1341-1349
Main Authors: Shim, Won Mok, Alvarez, G. A., Vickery, T. J., Jiang, Y. V.
Format: Article
Language:English
Subjects:
Adult
Attention - physiology
attentive tracking
Brain Mapping
Female
fMRI
Humans
Magnetic Resonance Imaging
Male
Motion Perception - physiology
Neuropsychological Tests
Parietal Lobe - anatomy & histology
Parietal Lobe - physiology
Photic Stimulation
posterior parietal cortex
Reaction Time - physiology
Space Perception - physiology
visual attention
Visual Cortex - anatomy & histology
Visual Cortex - physiology
Visual Pathways - physiology
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Summary:Many everyday tasks require us to track moving objects with attention. The demand for attention increases both when more targets are tracked and when the targets move faster. These 2 aspects of attention—assigning multiple attentional foci (or indices) to targets and monitoring each focus with precision—may tap into different cognitive and brain mechanisms. In this study, we used functional magnetic resonance imaging to quantify the response profile of dorsal attentional areas to variations in the number of attentional foci and their spatiotemporal precision. Subjects were asked to track a specific spoke of either 1 or 2 pinwheels that rotated at various speeds. Their tracking performance declined both when more pinwheels were tracked and when the tracked pinwheels rotated faster. However, posterior parietal activity increased only when subjects tracked more pinwheels but remained flat when they tracked faster moving pinwheels. The frontal eye fields and early visual areas increased activity when there were more targets and when the targets rotated faster. These results suggest that the posterior parietal cortex is specifically involved in indexing independently moving targets with attention but not in monitoring each focus with precision.
ISSN:1047-3211
1460-2199
DOI:10.1093/cercor/bhp197