Mechanisms of pattern discrimination in the toad´s visual system

The authors propose that the toad discriminates visual objects based on temporal responses and that discrimination is reflected in different average neuronal firing rates at some higher visual center, hypothetically the anterior thalamus. This theory is developed through a large-scale neuronal simulation which includes retina, tectum, and anterior thalamus. The neural model based on this theory predicts that retinal R2 cells play a primary role in the discrimination via tectal small pear cells (SP) and R3 cells refine the feature analysis by inhibition. The simulation demonstrates that the retinal response to the trailing edge of a stimulus is as crucial for pattern discrimination as the response to the leading edge. The new dishabituation hierarchies are predicted by this model by shrinking stimulus size and reversing contrast