Spectral sensitivity Spectral sensitivity Spectral sensitivity is the relative efficiency of detection, of light or other signal, as a function of the frequency or wavelength of the signal. In visual neuroscience, spectral sensitivity is used to describe the different characteristics of the photopigments in the rod cells and cone cells in the retina of the eye. It is known that the rod cells are more suited to scotopic vision and cone cells to photopic vision, and that they differ in their sensitivity to different wavelengths of light. It has been established that the maximum spectral sensitivity of the human eye under daylight
Tetrachromacy the brain would respond if presented with a new color channel. Mice, which normally have only two cone pigments, can be engineered to express a third cone pigment, and appear to demonstrate increased chromatic discrimination, arguing against some of these obstacles; however, the original publication's claims about plasticity in the optic nerve have also been disputed. Humans cannot see ultraviolet light directly because the lens of the eye blocks most light in the wavelength range of 300–400 nm; shorter wavelengths are blocked by the cornea. The photoreceptor cells of the retina are sensitive to near ultraviolet light, and people lacking