Spatial learning by rats across visually disconnected environments

Experiments were designed in which some properties of spatial representatio ns in rats could be examined. Adult subjects were trained to escape through a hole at a fixed position in a large circular arena (see Schenk, 1989). T he experiments were conducted in the dark, with a limited number of control led visual light cues, in order to assess the minimal cue requirement for p lace learning. Three light cues identical in shape, height, and distance fr om the table were used. Depending on the condition, they were either perman ently on or alternatively on or off, contingent on the position of the rat in the field. Two questions were asked: (1) How many identical visual cues were necessary for spatial discrimination in the dark, and (2) could rats i ntegrate the relative positions of separate cues, under conditions in which the rat was never allowed to perceive all three cues simultaneously. The r esults suggest that rats are able to achieve a place discrimination task ev en if the three cues necessary for efficient orientation can never be seen simultaneously. A dissociation between the discrimination of the spatial po sition of the goal and the capacity to reach it by a direct path suggests t hat, with a reduced number of cues, prolonged locomotion might be required for accurate orientation in the environment.