A functional MRI case study of acquired cerebral dyschromatopsia

Evidence from imaging studies suggests that primary visual cortex and multi ple areas in ventral occipitotemporal cortex subserve color perception in h umans. To learn more about the organization of these areas, we used structu ral and functional MRI (fMRI) to examine a patient with damage to ventral c ortex. An art professor. KC, suffered a cerebrovascular accident during hea rt surgery that impaired his ability to perceive color. The Farnsworth-Muns ell 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 norm als on the 100-Hue test, but well above chance. Structural and functional M RI studies were conducted 3 years after the lesion to investigate the neuro anatomical correlates of KG'ss remaining color ability. Structural MRI reve aled 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 an d 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 act ivity was observed in left anterior ventral cortex. However, significant co lor-selective activity was observed in posterior left ventral cortex spared by the lesion. This posterior left ventral activation was similar in exten t, position, and degree of color-selectivity to the posterior left posterio r activation observed in normal controls, suggesting that this focus may be the cortical substrate underlying KG's remaining color perception. Publish ed by Elsevier Science Ltd.