Effect of lesions of the ventral noradrenergic bundle on the two-way avoidance behavior in rats.

Bilateral electrolytic lesions of the ventral noradrenergic bundle (VB) were performed in Wistar male rats. Seven to eight days after the surgery animals were trained for two-way avoidance behavior (10 days, 15 trials per day). Lesions of the VB facilitated avoidance acquisition and slightly increased intertial responses. The latency of avoidance reaction as well as latency of escape was unchanged in VB-lesioned animals. The possible role of VB in mechanism of learning is discussed. It is pointed out that VB may play an opposite role to the dorsal noradrenergic bundle which is known to facilitate learning.