The role of the parietal cortex in visual feature binding - PubMed (original) (raw)
The role of the parietal cortex in visual feature binding
Keith M Shafritz et al. Proc Natl Acad Sci U S A. 2002.
Abstract
When multiple objects are simultaneously present in a scene, the visual system must properly integrate the features associated with each object. It has been proposed that this "binding problem" is solved by selective attention to the locations of the objects [Treisman, A.M. & Gelade, E. (1980) Cogn. Psychol. 12, 97-136]. If spatial attention plays a role in feature integration, it should do so primarily when object location can serve as a binding cue. Using functional MRI (fMRI), we show that regions of the parietal cortex involved in spatial attention are more engaged in feature conjunction tasks than in single feature tasks when multiple objects are shown simultaneously at different locations but not when they are shown sequentially at the same location. These findings suggest that the spatial attention network of the parietal cortex is involved in feature binding but only when spatial information is available to resolve ambiguities about the relationships between object features.
Figures
Fig 1.
Definition of spatial attention ROIs. (A) Trial design. Each block of trials began with a screen instructing the subjects which feature to attend. In each trial, two snowflake objects were presented, followed by a mask and a test object. Subjects determined whether the test matched one of the two sample objects in the attended feature (shape or location). Object colors were uninformative for the shape and location judgments and were used for pilot experiments of feature conjunctions (data not shown). (B) Brain activation for location (red) compared to shape judgment (blue). Location judgment activated two regions of the parietal cortex: anterior intra-parietal (green arrow) and superior parietal (BA7) cortex (purple arrow).
Fig 2.
Experiment 2. (A) Trial design. Each block of trials began with a screen instructing the subjects which feature(s) to attend. In the simultaneous presentation trials, the two sample objects were spatially separated but shown simultaneously, whereas in the sequential presentation trials, the two objects were shown successively at fixation point. The sample objects were followed by a mask and then a test object. (B) Behavioral performance during the fMRI sessions.
Fig 3.
(A) Direct comparison of conjunction-related activation in the simultaneous (yellow) and sequential (blue) presentations. Green and purple boxes indicate the position of the intra- and superior parietal ROIs, respectively. The simultaneous-presentation activation largely overlaps with the parietal ROIs. (B) Activation of parietal ROIs with conjunction and single feature judgments. Both the right intra- and superior parietal ROIs were more activated during the conjunction judgments than during either of the single feature judgments in the simultaneous presentation mode only (asterisks). Yellow voxels in the statistical parametric map represent brain areas significantly more activated for the conjunction judgment than for both of the single feature judgments during the simultaneous presentations condition (voxels met criteria of P < 0.05 for each of the two conjunction vs. single-feature comparisons). The activated voxels overlap with the ROIs.
References
- DeYoe E. A. & Van Essen, D. C. (1988) Trends Neurosci. 11**,** 219-226. -PubMed
- Treisman A. M. & Gelade, G. (1980) Cognit. Psychol. 12**,** 97-136. -PubMed
- Wolfe J. M. & Cave, K. (1999) Neuron 24**,** 11-17. -PubMed
Publication types
MeSH terms
LinkOut - more resources
Full Text Sources
Other Literature Sources