THE POSITION AND TOPOGRAPHY OF THE HUMAN COLOR-CENTER AS REVEALED BY FUNCTIONAL MAGNETIC-RESONANCE-IMAGING

We used a colour Mondrian-an abstract scene with no recognizable objec ts-and its achromatic version to image the change in blood oxygenation in the brains of 12 human subjects, with the aim of learning more abo ut the position and variability of the colour centre in the human brai n. The results showed a consistent association of colour stimulation w ith activation of an area that is distinct from the primary visual are as, and lies in the ventral occipitotemporal cortex; we refer to it as human V4. The position of human V4, as defined on functional grounds, varies between individuals in absolute terms but is invariably found on the lateral aspect of the collateral sulcus on the fusiform gyrus. There was no indication of lingual gyral activation. In further studie s designed to reveal the topographic map within V4, we stimulated the superior and inferior visual fields separately using the same stimuli. We found that human V4 contains a representation of both the superior and inferior visual fields. In addition, there appears to be retinoto pic organization of V4 with the superior visual field being represente d more medially on the fusiform gyrus and the inferior field more late rally the two areas abutting apt one: another We find no evidence that suggests the existence of a separate representation of the inferior h emifield for colour in more dorsolateral regions of the occipital lobe .