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Abstract:
Abstract: Primary visual cortex and multiple areas in ventral
occipitotemporal cortex subserve color perception in humans. To
learn more about the organization of these areas, we used
structural and functional MRI (fMRI) to examine a patient with
damage to ventral cortex. KG suffered a cerebrovascular accident
during heart surgery that impaired his ability to perceive color.
The Farnsworth-Munsell 100-Hue test was used to assess the extent
of his deficit. When tested 12 months after the lesion, KG
performed worse than 95% of age-matched normals on the 100-Hue
test, but well above chance. Structural and functional MRI studies
were conducted three years after the lesion. Structural MRI
revealed bilateral damage to ventral occipitotemporal cortex. In
young and age-matched normal controls, an fMRI version of the
100-Hue reliably activated bilateral, color-selective regions in
primary visual cortex and anterior and posterior ventral cortex. In
subject KG, color-selective cortex was found in bilateral primary
visual cortex. In ventral cortex, no color-selective activity was
observed in right ventral cortex, and only a small area of activity
was observed in left anterior ventral cortex. Significant
color-selective activity was observed in posterior left ventral
cortex spared by the lesion. This posterior left ventral activation
was similar in extent, position, and degree of color-selectivity to
the posterior left posterior activation observed in normal controls
and may be the cortical substrate underlying KG's remaining color
perception.
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