Colour centre in humans as an area specialized for colour vision. V2, also called the prestriate cortex, is believed to have a small role in colour processing by projecting signals from V1 to the V4-complex. Whether or not colour selective cells are present in V2 is still being investigated. Some optical imaging studies have found small clusters of red-green colour selective cells in V1 and V2, but not any blue-yellow colour selective cells. Other studies have shown that V2 is activated by colour stimuli, but not colour after images.[8] V4 also has feedback on V2, suggesting that there is a defined network
Colour centre cannot track the actual firing of neurons, which happen on a millisecond timescale, but it can track the haemodynamic response, which happens on a seconds timescale. This method is ideal for tracking colour selective neurons because colour perception results in a visual after-image that can be observed in the neurons, which lasts about 15 seconds. Sakai et al. used fMRI to observe whether activation of the fusiform gyrus correlated with the perception of colour and the after image. The subjects in the Sakai study were placed in the fMRI machine and were subsequently subjected to various visual stimuli. A series