Neural substrates of discriminative avoidance learning and classical eyeblink conditioning in rabbits: a double dissociation.

In a previous study, lesions of the deep cerebellar nuclei blocked classical eyeblink conditioning, but did not impair discriminative avoidance learning in rabbits. Here, was also found previously, lesions of the anterior and medial dorsal thalamic nuclei severely impaired discriminative avoidance learning. However, these lesions had no impact on discriminative eyeblink conditioning or reversal learning. These results complete the demonstration of a double dissociation, indicating distinct neural substrates for the acquisition of these learned behaviors. It is proposed that the two learning circuits identified by these studies mediate, respectively, acquisition of specific adaptive reflexes and whole-body, voluntary goal-directed movements.