The muscles which trigger the targeted tongue flick are guided by the salamander's optical impressions. The exact location of the retina stimulus is assessed via the optical nerve in the meso-encephalus. This amphibian visual center is characterized by a very exact map of the range of vision. From here, the neuron extensions can directly influence the motor neurons, which in turn guide the animal's neck muscles, bringing the head into the proper position. It is more difficult, however, to estimate the exact distance of an object in the range of vision.
Observations show salamanders use their tongue-flick very discriminatingly.
In us humans, distance is determined by lens accommodation, which is equivalent to the focusing of a camera objective, and visual convergence, that is the fixation on an object using both eyes. The anatomy of the salamander's eyes assigns only a minor role to both accommodation and convergence, but is very well suited to stereoscopic vision. Distance is determined by evaluating the two different images that appear on the retinas of the left and the right eyes. Thus, the salamander's brain is capable of very complicated and interactive information processing despite its limited number of nerve cells. That is why physicist Christian Eurich has set out to simulate the salamander's perception mechanisms by means of a neuronal network.