Rethinking Colour vision
Most image-forming animal eyes encode light as a function of space, time, and wavelength. “Colour vision” is associated with the latter. At its most fundamental level, decoding wavelength information in light requires combining the signals from just two spectrally distinct photoreceptors neurons. Such a basic circuit does not require sophisticated eye optics, and accordingly forms of rudimentary spectral opponency is thought to long predate image forming vision. “Colour vision” was therefore probably also already a key staple ingredient of retinal circuits when early proto-vertebrates began evolving full-blown eyes during the Cambrian. But then, was it really the ability to “see colour” that underpins ‘colour circuits’ we see in the eyes and brains of animals today? Our work strongly suggests that the answer is “No”.
