The Dorsal Subiculum Is Not Necessary for Step-Through Inhibitory Avoidance Acquisition and Consolidation in Rats

The dorsal subiculum (DSub) has reciprocal connections with the dorsal hippocampus, and these regions play a role in spatial representation in contextual fear conditioning (CFC). Recently, we used AP5 and muscimol infusions to show that the DSub is required for CFC consolidation. The CFC component can be present in other learning tasks, such as step-through inhibitory avoidance (ST IA), which requires the dorsal hippocampus for acquisition and consolidation. This suggests that the DSub may be also involved in ST IA if the CFC component of the protocol is strong enough. Therefore, this study tested whether the DSub participates in ST IA acquisition and consolidation in male Wistar rats. Our data showed that pre-or posttraining infusions of AP5 or muscimol into the DSub did not affect ST IA acquisition and consolidation. We discuss the present results in relation to our previous findings, which showed the involvement of the DSub in CFC consolidation, and highlight some reasons that may explain the divergent results between the tasks. First, we note the possibility to escape from the unconditioned stimulus that occurs in ST IA, but not in CFC. We also suggest that the instrumental component of ST IA seems to be more prominent than the CFC one. Finally, we consider the possible influence of aspects of anxiety present in the ST IA, but not in CFC. These possible interpretations provide a broad framework in respect of the present results and raise new questions that demand further studies exploring the DSub function in inhibitory avoidance.