Effects of electrolytic lesion of medial septal nucleus on learning strategy selection in a visible platform version of the water maze.

This experiment investigated the ability of sham-operated and medial septal (MS) damaged rats to learn the location of a visible, as well as submerged platform in a water maze. The rats' responses on the competition test were classified as either cue or place, based on the swim path for those trials. Sham-operated rats acquired both the visible and hidden platform versions of the task, but when required to choose between the spatial location they had learned and the visible platform in a new location majority of them swam first to the old spatial location. The MS damaged rats acquired the visible platform version of the water maze task but failed to learn the platform's location in space. When the visible platform was moved to a new location they often swam directly to it. Sham-operated rats identified as place responders had significantly more accurate searches during hidden platform training, providing additional evidence of their effective use of a place learning strategy than MS is damaged. These findings suggest that in the absence of a septohippocampal functional system behaviour was not affected by spatial information and responding to local reinforced cues was enhanced. These data add to a growing literature demonstrating that the septo-hippocampal system is essential for accurate spatial learning and suggest its role in processing information about the spatial environment.