ABSTRACT
The eye contains two types of light-sensitive cell, rods and cones, which are attached to the retina. The receptive field of a neuron in the visual pathway is that area of the retina which, when stimulated by light, will cause activity in that neuron. Receptive fields can be very complex; for example, a cell in the visual cortex may respond only when its receptive field is stimulated by a dark line moving diagonally across it. By changing the color of the light and the area of the retina being stimulated, it is possible to show that the first part of the curve is due to adaptation of the cones, which reach their maximum sensitivity after about 10 min. The physiological basis for color vision is that there are three types of cone, each of which contains a different color-absorbing pigment that is maximally sensitive to different wavelengths of light. The trichromatic theory predicts five different types of color vision deficiency.
