Neurophysiology of the Anuran Visual System

Due to recent behavioral and electrophysiological data found in different anurans, some investigators believe that the visual system of frogs and toads is a highly specialized machinery which detects only self-moving visual signals relevant to the survival of the animals (p. 357 f., 435 ff.). Other visual signals are believed to be “suppressed” by the neuronal network of the visual system. Thus the ironic poem of Heinrich Heine would be incorrect as such a neuronal machine leaves little possibility for frogs to “erquicken… an Sonnenblicken”. The angular velocity of the sun and the shadows cast by stationary objects in the frog’s habitat would be too slow to be discovered by the movement-detecting neuronal systems.