Participation of thalamic nuclei in the elaboration of conditioned avoidance reflexes of rats. VIII. Lesions of the nucleus posterior.

Bilateral symmetric lesions of the posterior thalamic nucleus reduced the preoperatively learnt avoidance responses in Long-Evans hooded rats strongly. Postoperative acquisition of conditioned avoidance reflexes was rather low in each rat in a simple runway and impossible in an alternation task. Thresholds of reactions to pain (withdrawal of paws from the grid floor) were significantly increased. The lesioned rats had trouble to find the way out, as if they had difficulties to localize the source of punishment or to associate pain information with any other cues.