Sensory maps and brain development the midbrain auditory nucleus had receptive fields independent of nature and intensity of the sound. Roger Sperry proposed a chemical gradient model for eye rotation and for neuronal wiring diagram. Retinal neurons and target cells had identification tags in the form of chemical gradients so that the projection of neurons would be orderly. For a topographic map of the visual world, the map first forms during neural development via molecular signals, such as chemospecific matching between molecular gradients. The molecular basis of sensory maps and brain development is a field that is being actively explored. The most recent work has
Visual phototransduction Visual phototransduction Visual phototransduction is the sensory transduction of the visual system. It is a process by which light is converted into electrical signals in the rod cells, cone cells and photosensitive ganglion cells of the retina of the eye. This cycle was elucidated by George Wald (1906–1997) for which he received the Nobel Prize in 1967. It is so called "Wald's Visual Cycle" after him. The visual cycle is the biological conversion of a photon into an electrical signal in the retina. This process occurs via G-protein coupled receptors called opsins which contain the chromophore 11-cis retinal. 11-cis retinal