The architecture of the colour centre in the human visual brain: new results and a review

We have used the technique of functional magnetic resonance imaging (fMRI) and a variety of colour paradigms to activate the human brain regions selec tive for colour. We show here that the region defined previously [Lueck et al. (1989) Nature, 340, 386-389; Zeki et al. (1991) J. Neurosci., 11, 641-6 49; McKeefry & Zeki (1997) Brain, 120, 2229-2242] as the human colour centr e consists of two subdivisions, a posterior one, which we call V4 and an an terior one, which we refer to as V4 alpha, the two together being part of t he V4-complex. The posterior area is retinotopically organized while the an terior is not. We discuss our new findings in the context of previous studi es of the cortical colour processing system in humans and monkeys. Our new insight into the organization of the colour centre in the human brain may a lso account for the variability in both severity and degree of recovery fro m lesions producing cerebral colour blindness (achromatopsia).