Responses of retinal and tectal neurons in non-paralyzed toads Bufo bufo and B. marinus to the real size versus angular size of objects moved at variable distance.

Toads judge the real size of moving visual objects during prey-catching. But neither ganglion cells of the retinotectal projection nor tectal neurons showed a comparable phenomenon in muscle paralyzed toads. In non-paralyzed toads, however, tectal neurons, unlike neurons, displayed a sensitivity to the real size of an object moving at variable distance to the animal. Interestingly, this property was obtained both in monocular T5 smallfield neurons and in most of the investigated T4 widefield neurons.