Evolution of human colour vision that are found between 450 and 625. Individuals with various forms of colour blindness such as deuteranopia and protanopia are missing human middle wavelength sensitive or long wavelength sensitive opsins. Their minimum wavelength differences are <5 but only at around 500. Protanopes, who are missing long wavelength sensitive cones, are unable to distinguish between colours in the green-yellow-red section of the electromagnetic spectrum. They find yellow, red and orange colours to have much lower brightness when compared to a trichromat. The dimming of these colours can result in confusion in many cases, such as when attempting to identify red traffic
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