PREY-CATCHING BEHAVIOUR OF TOADS (BUFO BUFO L) WITH DIENCEPHALIC AND PRETECTAL LESIONS TO MOVING AND NONMOVING VISULA STIMULI

The prey-catching behaviour of Anura (orienting movement, binocular fixation and snapping) is released by the moving stimulus of a small visual pattern. - Moving patterns on the retinal can result from different stimulus situations. Situation I: Around the toad is moving a small visual pattern in horizontal direction. Situation II: The toad is moving and perceives the visual stimuli of its own moving hind extremities. Situation III: The toad passes a small and immovable visual pattern. - With prey-catching movements, however, the toad reacts only in stimulus situation I. - The ability of the toad to differentiate between behaviourally relevant key stimuli and behaviourally irrelevant stimuli in preycatching is based on certain functions of the CNS. It can be shown that this ability is eliminated after caudal thalamic and pretectal lesions. Then the animals react to all 3 stimulus situations (I, II, III) with prey-catching. © 1969 Springer-Verlag.