Spectral sensitivity spectral sensitivity may be expressed as a spectral responsivity, with units such as amperes per watt. 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
Retina is the only part of the CNS that can be visualized non-invasively. The vertebrate retina is "inverted" in the sense that the light sensing cells are in back of the retina, so that light has to pass through layers of neurons and capillaries before it reaches the rods and cones. In contrast, in the cephalopod retina the photoreceptors are in front, with processing neurons and capillaries behind them. Because of this, cephalopods do not have a blind spot. The overlying neural fibre layer does not degrade vision in the inverted retina. The neurons are transparent and the accompanying glial cells