Ablation of nucleus isthmi leads to loss of specific visually elicited behaviors in the frog Rana pipiens.

Ablation of the frog's nucleus isthmi results in a visual scotoma contralateral to the lesion. Within the scotoma, animals do not respond to visually presented prey or threats. The locus of visual loss is related to the area of isthmal tissue ablated. With complete unilateral ablation, a frog displays no visually elicited prey-catching or threat-avoidance behaviors in the entire monocular field.