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The retinotopy of visual spatial attention
R B Tootell1, N Hadjikhani, E K Hall
1Nuclear Magnetic Resonance Center, Massachusetts General Hospital, Charlestown, 02129, USA. tootell@nmr.mgh.harvard.edu
Neuron
|January 12, 1999
Summary
Functional magnetic resonance imaging (fMRI) revealed that visual spatial attention increases cortical activity in specific visual areas. Attention directed elsewhere decreased activity in those same visual processing regions.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Neuroimaging
Background:
- Visual spatial attention modulates neural activity in the human visual cortex.
- Understanding the precise cortical mechanisms of attention is crucial for cognitive neuroscience.
Purpose of the Study:
- To investigate the relationship between visual spatial attention and cortical activity using functional magnetic resonance imaging (fMRI).
- To map the effects of attention on retinotopic and extrastriate visual areas.
Main Methods:
- High-field (3T) fMRI was employed in human subjects.
- Cortical activity was measured while varying the location and load of covert visual spatial attention with a constant visual stimulus.
- Activity was analyzed relative to flattened cortical maps of retinotopy and visual areas.
Main Results:
- Increased magnetic resonance (MR) signal was observed in extrastriate retinotopic areas and V1 corresponding to attended visual targets.
- Decreased MR signal occurred in these same areas when attention was directed to different locations.
- Lateralized increases and prominent decreases in MR signal were noted in and around area MT+.
Conclusions:
- Visual spatial attention selectively enhances neural activity in retinotopically organized visual areas.
- Attention has distinct effects on different visual areas, including lateralization in area MT+.
- fMRI is a valuable tool for mapping the neural correlates of visual attention.