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
Pinky and the Brain Labs research facility. Brain is self-centered and scheming, Pinky is good-natured but feebleminded. In each episode, Brain devises a new plan to take over the world which ultimately ends in failure: usually due to Pinky's idiocy, the impossibility of Brain's plan, Brain's own arrogance, or just circumstances beyond their control. In common with many other "Animaniacs" shorts, many episodes are in some way a parody of something else, usually a film or novel. Many of the "Pinky and the Brain" episodes occur in the 1990s at Acme Labs, located in some large American city underneath a suspension bridge. Several episodes