Rats with hippocampal lesions learn about allocentric place cues in a non-navigational task

Hippocampal-lesioned rats (HPC) and sham controls (SH) learned constant-neg ative visual discriminations among scenes in a Y-maze. Any arm could be sta rt arm for a trial. Two choice scenes ("constant" and "variable") were show n in the other arms. In Experiment 1, each problem had 2 constants. One or the other constant appeared on every trial, and the variable changed every trial; choosing the variable was rewarded. There were 4 problem types. Each constant might be always in a given direction from the start arm (added eg ocentric [Ego] cue), always in a given maze arm (added allocentric [Allo] c ue), both, or neither. SH rats' visual learning was enhanced by Ego and by Allo cues. HPC rats' visual learning was enhanced by Ego cues, and by Allo cues, but only if there was no Ego cue. Experiment 2 confirmed that Allo cu es helped HPC mts as much as SH, in the absence of Ego cues. Rats with HPC lesions can learn about allocentric place cues when navigation and idiothet ic cue control are not required.