Research reportABA and ABC renewal of conditioned magazine approach are not impaired by dorsal hippocampus inactivation or lesions

- Our appetitive renewal designs controlled for test contexts' associative histories.
- Neither lesions nor inactivation of the dorsal hippocampus impaired renewal.
- Both neural manipulations impaired performance on probe tasks.
- Renewal may sometimes depend on different underlying psychological mechanisms.
- The dorsal hippocampus may not be involved in all instances of renewal.

Three experiments investigated the role of the dorsal hippocampus (DH) in renewal of conditioned and then extinguished magazine approach responding in rats. Experiments 1 and 2 found no effect of muscimol inactivation of the DH during testing on ABA and ABC renewal, respectively. However, subjects from these studies were subsequently found to be impaired on a delayed non-matching-to-place task following muscimol but not saline infusions. Experiment 3 found no effects of post-training excitotoxic lesions of the DH on ABA and ABC renewal. Lesioned subjects were, however, impaired on the delayed non-matching-to-place task compared to control subjects. These findings suggest that the DH may not play a similar role in Pavlovian extinction in appetitive learning tasks as has previously been reported in aversive learning.