BLOCK DIAGRAM OF THE SIGNALING SYSTEM IN HUMAN VISION

The signaling architecture of the visual system used in long wavelength trichromats (humans and other large terrestrial mammals) is shown in the following figure. This figure emphasizes the three distinct signaling paths found in vision (the P-, Q- and R-channels) as well as the unique correlation channel (labeled the G'-channel) found in only the highest primates (hominoidea) and used by the analytical mode of vision for reading and other functions requiring maximum acuity and perception of detail.