Rats with hippocampal lesions learn about allocentric place cues in a non-navigational task.
Gaffan EA., Bannerman DM., Healey AN.
Hippocampal-lesioned rats (HPC) and sham controls (SH) learned constant-negative visual discriminations among scenes in a Y-maze. Any arm could be start arm for a trial. Two choice scenes ("constant" and "variable") were shown 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 egocentric [Ego] cue), always in a given maze arm (added allocentric [Allo] cue), 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 cues helped HPC rats as much as SH, in the absence of Ego cues. Rats with HPC lesions can learn about allocentric place cues when navigation and idiothetic cue control are not required.