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Retinotopy and color sensitivity in human visual cortical area V8
N Hadjikhani1, A K Liu, A M Dale
1Nuclear Magnetic Resonance Center, Massachusetts General Hospital, Charlestown 02129, USA. nouchine@nmr.mgh.harvard.edu
Nature Neuroscience
|April 9, 1999
Summary
Researchers identified a new human visual cortex area, V8, crucial for color processing. This area, distinct from macaque V4, shows preferential activation to color stimuli and afterimages.
Area of Science:
- Neuroscience
- Visual Neuroscience
- Human Brain Imaging
Background:
- Previous research suggested a human color-selective area in the inferior occipital-temporal cortex.
- This area was hypothesized to be homologous to the macaque V4 area, known for color selectivity.
Purpose of the Study:
- To directly test the homology between the human color-selective region and macaque area V4.
- To precisely map the location of the human color-selective area relative to retinotopic boundaries.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was employed to study brain activity.
- Cortical flattening and retinotopic mapping techniques were utilized in human subjects.
- Stimuli producing color afterimages were used to further probe visual cortex responses.
Main Results:
- The human color-selective region did not align with the extrapolated location of macaque area V4.
- A novel retinotopic area, designated 'V8', was identified, encompassing foveal and peripheral visual field representations.
- Area V8, but not V4, demonstrated preferential activation to both real colors and color afterimage stimuli.
Conclusions:
- The human color-selective area is not homologous to macaque area V4.
- A new distinct human visual area, V8, is identified and characterized by its role in color processing.
- Area V8's activation by color afterimages further supports its specialization for color perception.