Colours light up brain structure
Neuronal circuits can now be seen in a multicolour 'brainbow'.
A mix of 5 colours can produce about 90 distinct shades.
Nature (once again) has a wonderful paper about a new coloring technique able to randomly color every neuron with about 90 different shades so that their wiring can be seen more clearly.
Here it is, better written than I ever will be able to.