Place navigation in the Morris water maze under minimum and redundant extra-maze cue conditions.
Complex relational processes underlying place navigation learning were analyzed by minimizing the relational elements available to rats. The animals navigated in a standard water maze in darkness using controlled remote visual cues (back-lit shapes in opaque buckets aimed at the pool to keep the background dark) while being tracked by an infrared camera and computer. Learning was similar with 2 (AB) or 4 (ABCD) cues and as good as in a fully lit room with many cues (asymptotic escape time t = 5-7 s). The ABCD-trained rats were not impaired by removal of any 2 cues (t = 7). For AB-trained rats, adding 2 new cues (ABEF) or replacing AB with EF (EF) caused small (t = 11) or big disruptions (t = 20), respectively. By block 2, both groups (ABEF, EF) returned to asymptotic performance. But testing the ABEF rats on block 2 with only EF indicated that EF was learned (t = 12) but not as well as when only EF was present (t = 5). Thus transfer from a redundant to a minimal cue condition is immediate and easier than vice versa. Theoretical implications are discussed.
Institute of Physiology, Academy of Sciences, Prague, Czech Republic.
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Fenton
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Arolfo
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Nerad
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Bures
D001245:Association Learning; D001288:Attention; D003463:Cues; D004193:Discrimination Learning; D004924:Escape Reaction; D006801:Humans; D008297:Male; D018782:Maze Learning; D011939:Mental Recall; D009949:Orientation; D012153:Retention, Psychology; D014163:Transfer, Psychology; D014796:Visual Perception