Walsh & Hoyt: Functional Imaging

A variety of brain-mapping studies support the existence of an extrastriate region specialized for color perception. PET first demonstrated color-selective responses in the lingual and fusiform gyri. Selective attention to the color of a stimulus increased blood flow in the lingual and fusiform gyri. fMRI has shown increased signal with colored stimuli and also during a color after-effect in the posterior fusiform gyri. Visual evoked potentials using depth and surface electrodes in epileptic patients have shown that stimuli of changing colors were associated with peaks at 200 to 300 ms in the lateral lingual gyrus and posterior fusiform gyrus. Also, stimulating at these sites specifically caused alterations in color perception in some patients.