Electrolytic and ibotenic acid lesions of the nucleus basalis magnocellularis interrupt long-term retention, but not acquisition of two-way active avoidance,in rats

Previous experiments on two-way active avoidance have shown conflicting results after nucleus basalis magnocellularis lesion: disrupting effects with electrolytic lesions and facilitative effects with excito-toxic lesions. To resolve this issue, in this experiment, Wistar rats received pre-training bilateral electrolytic or ibotenic acid lesions and were trained in a massed two-way active avoidance conditioning. In order to test the long-term retention of the learned response, one additional session was conducted 10 days after the acquisition. Results showed that whereas electrolytic lesions did not affect the acquisition, ibotenic acid lesions enhanced it. Retention of active avoidance response was impaired by both electrolytic and ibotenic lesions of the NBM. These results suggest a role of the NBM in the memory consolidation and/or retrieval of two-way active avoidance.